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  • Why would using a Temp table be faster than a nested query?

    - by Mongus Pong
    We are trying to optimise some of our queries. One query is doing the following: SELECT t.TaskID, t.Name as Task, '' as Tracker, t.ClientID, (<complex subquery>) Date, INTO [#Gadget] FROM task t SELECT TOP 500 TaskID, Task, Tracker, ClientID, dbo.GetClientDisplayName(ClientID) as Client FROM [#Gadget] order by CASE WHEN Date IS NULL THEN 1 ELSE 0 END , Date ASC DROP TABLE [#Gadget] (I have removed the complex subquery, cos I dont think its relevant other than to explain why this query has been done as a two stage process.) Now I would have thought it would be far more efficient to merge this down into a single query using subqueries as : SELECT TOP 500 TaskID, Task, Tracker, ClientID, dbo.GetClientDisplayName(ClientID) FROM ( SELECT t.TaskID, t.Name as Task, '' as Tracker, t.ClientID, (<complex subquery>) Date, FROM task t ) as sub order by CASE WHEN Date IS NULL THEN 1 ELSE 0 END , Date ASC This would give the optimiser better information to work out what was going on and avoid any temporary tables. It should be faster. But it turns out it is a lot slower. 8 seconds vs under 5 seconds. I cant work out why this would be the case as all my knowledge of databases imply that subqueries would always be faster than using temporary tables. Can anyone explain what could be going on!?!?

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  • transforming 1d (1column) into 5d(5column) matrix through copy paste or other

    - by Curious
    Ex. I want to take the column with 12345..... and order 5 columns across as seen. next 5 numbers in column will be next row. However my code creates a 4 row gap in between each successive row. I dont know what additional logic (possibly if then statement) I can embed into do loop to may make it cleaner. I am new to this, so showing as much sample code to learn the syntax would be most beneficial. thanks in advance. Below is the Result of my code. VBA code is below result. 1 1 2 3 4 5 2 3 4 5 6 6 7 8 9 10 7 8 9 10 11 11 12 13 14 15 12 13 14 15 16 16 17 17 Sub Working_Code() ' Working_Code Macro Do ActiveCell.Select Selection.Copy ActiveCell.Offset(0, 5).Select ActiveSheet.Paste ActiveCell.Offset(1, -5).Select Selection.Copy ActiveCell.Offset(-1, 6).Select ActiveSheet.Paste ActiveCell.Offset(2, -6).Select Selection.Copy ActiveCell.Offset(-2, 7).Select ActiveSheet.Paste ActiveCell.Offset(3, -7).Select Selection.Copy ActiveCell.Offset(-3, 8).Select ActiveSheet.Paste ActiveCell.Offset(4, -8).Select Selection.Copy ActiveCell.Offset(-4, 9).Select ActiveSheet.Paste ActiveCell.Offset(5, -9).Select Loop Until IsEmpty(ActiveCell.Offset(0, -1)) End Sub

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  • Index question: Select * with WHERE clause. Where and how to create index

    - by Mestika
    Hi, I’m working on optimizing some of my queries and I have a query that states: select * from SC where c_id ="+c_id” The schema of ** SC** looks like this: SC ( c_id int not null, date_start date not null, date_stop date not null, r_t_id int not null, nt int, t_p decimal, PRIMARY KEY (c_id, r_t_id, date_start, date_stop)); My immediate bid on how the index should be created is a covering index in this order: INDEX(c_id, date_start, date_stop, nt, r_t_id, t_p) The reason for this order I base on: The WHERE clause selects from c_id thus making it the first sorting order. Next, the date_start and date_stop to specify a sort of “range” to be defined in these parameters Next, nt because it will select the nt Next the r_t_id because it is a ID for a specific type of my r_t table And last the t_p because it is just a information. I don’t know if it is at all necessary to order it in a specific way when it is a SELECT ALL statement. I should say, that the SC is not the biggest table. I can say how many rows it contains but a estimate could be between <10 and 1000. The next thing to add is, that the SC, in different queries, inserts the data into the SC, and I know that indexes on tables which have insertions can be cost ineffective, but can I somehow create a golden middle way to effective this performance. Don't know if it makes a different but I'm using IBM DB2 version 9.7 database Sincerely Mestika

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  • Why does SQL Server 2000 treat SELECT test.* and SELECT t.est.* the same?

    - by Chris Pebble
    I butter-fingered a query in SQL Server 2000 and added a period in the middle of the table name: SELECT t.est.* FROM test Instead of: SELECT test.* FROM test And the query still executed perfectly. Even SELECT t.e.st.* FROM test executes without issue. I've tried the same query in SQL Server 2008 where the query fails (error: the column prefix does not match with a table name or alias used in the query). For reasons of pure curiosity I have been trying to figure out how SQL Server 2000 handles the table names in a way that would allow the butter-fingered query to run, but I haven't had much luck so far. Any sql gurus know why SQL Server 2000 ran the query without issue? Update: The query appears to work regardless of the interface used (e.g. Enterprise Manager, SSMS, OSQL) and as Jhonny pointed out below it bizarrely even works when you try: SELECT TOP 1000 dbota.ble.* FROM dbo.table

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  • LINQ To SQL Dynamic Select

    - by mcass20
    Can someone show me how to indicate which columns I would like returned at run-time from a LINQ To SQL statement? I am allowing the user to select items in a checkboxlist representing the columns they would like displayed in a gridview that is bound to the results of a L2S query. I am able to dynamically generate the WHERE clause but am unable to do the same with the SELECT piece. Here is a sample: var query = from log in context.Logs select log; query = query.Where(Log => Log.Timestamp > CustomReport.ReportDateStart); query = query.Where(Log => Log.Timestamp < CustomReport.ReportDateEnd); query = query.Where(Log => Log.ProcessName == CustomReport.ProcessName); foreach (Pair filter in CustomReport.ExtColsToFilter) { sExtFilters = "<key>" + filter.First + "</key><value>" + filter.Second + "</value>"; query = query.Where(Log => Log.FormattedMessage.Contains(sExtFilters)); }

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  • httpd high cpu usage slowing down server response

    - by max
    my client has a image sharing website with about 100.000 visitor per day it has been slowed down considerably since this morning when i checked processes i've notice high cpu usage from http .... some has suggested ddos attack ... i'm not a webmaster and i've no idea whts going on top top - 20:13:30 up 5:04, 4 users, load average: 4.56, 4.69, 4.59 Tasks: 284 total, 3 running, 281 sleeping, 0 stopped, 0 zombie Cpu(s): 12.1%us, 0.9%sy, 1.7%ni, 69.0%id, 16.4%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 16037152k total, 15875096k used, 162056k free, 360468k buffers Swap: 4194288k total, 888k used, 4193400k free, 14050008k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 4151 apache 20 0 277m 84m 3784 R 50.2 0.5 0:01.98 httpd 4115 apache 20 0 210m 16m 4480 S 18.3 0.1 0:00.60 httpd 12885 root 39 19 4296 692 308 S 13.0 0.0 11:09.53 gzip 4177 apache 20 0 214m 20m 3700 R 12.3 0.1 0:00.37 httpd 2219 mysql 20 0 4257m 198m 5668 S 11.0 1.3 42:49.70 mysqld 3691 apache 20 0 206m 14m 6416 S 1.7 0.1 0:03.38 httpd 3934 apache 20 0 211m 17m 4836 S 1.0 0.1 0:03.61 httpd 4098 apache 20 0 209m 17m 3912 S 1.0 0.1 0:04.17 httpd 4116 apache 20 0 211m 17m 4476 S 1.0 0.1 0:00.43 httpd 3867 apache 20 0 217m 23m 4672 S 0.7 0.1 1:03.87 httpd 4146 apache 20 0 209m 15m 3628 S 0.7 0.1 0:00.02 httpd 4149 apache 20 0 209m 15m 3616 S 0.7 0.1 0:00.02 httpd 12884 root 39 19 22336 2356 944 D 0.7 0.0 0:19.21 tar 4054 apache 20 0 206m 12m 4576 S 0.3 0.1 0:00.32 httpd another top top - 15:46:45 up 5:08, 4 users, load average: 5.02, 4.81, 4.64 Tasks: 288 total, 6 running, 281 sleeping, 0 stopped, 1 zombie Cpu(s): 18.4%us, 0.9%sy, 2.3%ni, 56.5%id, 21.8%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 16037152k total, 15792196k used, 244956k free, 360924k buffers Swap: 4194288k total, 888k used, 4193400k free, 13983368k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 4622 apache 20 0 209m 16m 3868 S 54.2 0.1 0:03.99 httpd 4514 apache 20 0 213m 20m 3924 R 50.8 0.1 0:04.93 httpd 4627 apache 20 0 221m 27m 4560 R 18.9 0.2 0:01.20 httpd 12885 root 39 19 4296 692 308 S 18.9 0.0 11:51.79 gzip 2219 mysql 20 0 4257m 199m 5668 S 18.3 1.3 43:19.04 mysqld 4512 apache 20 0 227m 33m 4736 R 5.6 0.2 0:01.93 httpd 4520 apache 20 0 213m 19m 4640 S 1.3 0.1 0:01.48 httpd 4590 apache 20 0 212m 19m 3932 S 1.3 0.1 0:00.06 httpd 4573 apache 20 0 210m 16m 3556 R 1.0 0.1 0:00.03 httpd 4562 root 20 0 15164 1388 952 R 0.7 0.0 0:00.08 top 98 root 20 0 0 0 0 S 0.3 0.0 0:04.89 kswapd0 100 root 39 19 0 0 0 S 0.3 0.0 0:02.85 khugepaged 4579 apache 20 0 209m 16m 3900 S 0.3 0.1 0:00.83 httpd 4637 apache 20 0 209m 15m 3668 S 0.3 0.1 0:00.03 httpd ps aux [root@server ~]# ps aux | grep httpd root 2236 0.0 0.0 207524 10124 ? Ss 15:09 0:03 /usr/sbin/http d -k start -DSSL apache 3087 2.7 0.1 226968 28232 ? S 20:04 0:06 /usr/sbin/http d -k start -DSSL apache 3170 2.6 0.1 221296 22292 ? R 20:05 0:05 /usr/sbin/http d -k start -DSSL apache 3171 9.0 0.1 225044 26768 ? R 20:05 0:17 /usr/sbin/http d -k start -DSSL apache 3188 1.5 0.1 223644 24724 ? S 20:05 0:03 /usr/sbin/http d -k start -DSSL apache 3197 2.3 0.1 215908 17520 ? S 20:05 0:04 /usr/sbin/http d -k start -DSSL apache 3198 1.1 0.0 211700 13000 ? S 20:05 0:02 /usr/sbin/http d -k start -DSSL apache 3272 2.4 0.1 219960 21540 ? S 20:06 0:03 /usr/sbin/http d -k start -DSSL apache 3273 2.0 0.0 211600 12804 ? S 20:06 0:03 /usr/sbin/http d -k start -DSSL apache 3279 3.7 0.1 229024 29900 ? S 20:06 0:05 /usr/sbin/http d -k start -DSSL apache 3280 1.2 0.0 0 0 ? Z 20:06 0:01 [httpd] <defun ct> apache 3285 2.9 0.1 218532 21604 ? S 20:06 0:04 /usr/sbin/http d -k start -DSSL apache 3287 30.5 0.4 265084 65948 ? R 20:06 0:43 /usr/sbin/http d -k start -DSSL apache 3297 1.9 0.1 216068 17332 ? S 20:06 0:02 /usr/sbin/http d -k start -DSSL apache 3342 2.7 0.1 216716 17828 ? S 20:06 0:03 /usr/sbin/http d -k start -DSSL apache 3356 1.6 0.1 217244 18296 ? S 20:07 0:01 /usr/sbin/http d -k start -DSSL apache 3365 6.4 0.1 226044 27428 ? S 20:07 0:06 /usr/sbin/http d -k start -DSSL apache 3396 0.0 0.1 213844 16120 ? S 20:07 0:00 /usr/sbin/http d -k start -DSSL apache 3399 5.8 0.1 215664 16772 ? S 20:07 0:05 /usr/sbin/http d -k start -DSSL apache 3422 0.7 0.1 214860 17380 ? S 20:07 0:00 /usr/sbin/http d -k start -DSSL apache 3435 3.3 0.1 216220 17460 ? S 20:07 0:02 /usr/sbin/http d -k start -DSSL apache 3463 0.1 0.0 212732 15076 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3492 0.0 0.0 207660 7552 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3493 1.4 0.1 218092 19188 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3500 1.9 0.1 224204 26100 ? R 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3501 1.7 0.1 216916 17916 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3502 0.0 0.0 207796 7732 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3505 0.0 0.0 207660 7548 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3529 0.0 0.0 207660 7524 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3531 4.0 0.1 216180 17280 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3532 0.0 0.0 207656 7464 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3543 1.4 0.1 217088 18648 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3544 0.0 0.0 207656 7548 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3545 0.0 0.0 207656 7560 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3546 0.0 0.0 207660 7540 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3547 0.0 0.0 207660 7544 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3548 2.3 0.1 216904 17888 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3550 0.0 0.0 207660 7540 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3551 0.0 0.0 207660 7536 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3552 0.2 0.0 214104 15972 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3553 6.5 0.1 216740 17712 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3554 6.3 0.1 216156 17260 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3555 0.0 0.0 207796 7716 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3556 1.8 0.0 211588 12580 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3557 0.0 0.0 207660 7544 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3565 0.0 0.0 207660 7520 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3570 0.0 0.0 207660 7516 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL apache 3571 0.0 0.0 207660 7504 ? S 20:08 0:00 /usr/sbin/http d -k start -DSSL root 3577 0.0 0.0 103316 860 pts/2 S+ 20:08 0:00 grep httpd httpd error log [Mon Jul 01 18:53:38 2013] [error] [client 2.178.12.67] request failed: error reading the headers, referer: http://akstube.com/image/show/27023/%D9%86%DB%8C%D9%88%D8%B4%D8%A7-%D8%B6%DB%8C%D8%BA%D9%85%DB%8C-%D9%88-%D8%AE%D9%88%D8%A7%D9%87%D8%B1-%D9%88-%D9%87%D9%85%D8%B3%D8%B1%D8%B4 [Mon Jul 01 18:55:33 2013] [error] [client 91.229.215.240] request failed: error reading the headers, referer: http://akstube.com/image/show/44924 [Mon Jul 01 18:57:02 2013] [error] [client 2.178.12.67] Invalid method in request [Mon Jul 01 18:57:02 2013] [error] [client 2.178.12.67] File does not exist: /var/www/html/501.shtml [Mon Jul 01 19:21:36 2013] [error] [client 127.0.0.1] client denied by server configuration: /var/www/html/server-status [Mon Jul 01 19:21:36 2013] [error] [client 127.0.0.1] File does not exist: /var/www/html/403.shtml [Mon Jul 01 19:23:57 2013] [error] [client 151.242.14.31] request failed: error reading the headers [Mon Jul 01 19:37:16 2013] [error] [client 2.190.16.65] request failed: error reading the headers [Mon Jul 01 19:56:00 2013] [error] [client 151.242.14.31] request failed: error reading the headers Not a JPEG file: starts with 0x89 0x50 also there is lots of these in the messages log Jul 1 20:15:47 server named[2426]: client 203.88.6.9#11926: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 20:15:47 server named[2426]: client 203.88.6.9#26255: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 20:15:48 server named[2426]: client 203.88.6.9#20093: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 20:15:48 server named[2426]: client 203.88.6.9#8672: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:07 server named[2426]: client 203.88.6.9#39352: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:08 server named[2426]: client 203.88.6.9#25382: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:08 server named[2426]: client 203.88.6.9#9064: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:09 server named[2426]: client 203.88.23.9#35375: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:45:09 server named[2426]: client 203.88.6.9#61932: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:09 server named[2426]: client 203.88.23.9#4423: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:45:09 server named[2426]: client 203.88.6.9#40229: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:14 server named[2426]: client 203.88.23.9#46128: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:45:14 server named[2426]: client 203.88.6.10#62128: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:14 server named[2426]: client 203.88.23.9#35240: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:45:14 server named[2426]: client 203.88.6.10#36774: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:14 server named[2426]: client 203.88.23.9#28361: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:45:14 server named[2426]: client 203.88.6.10#14970: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:14 server named[2426]: client 203.88.23.9#20216: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:14 server named[2426]: client 203.88.23.10#31794: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:45:14 server named[2426]: client 203.88.23.9#23042: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:14 server named[2426]: client 203.88.6.10#11333: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:14 server named[2426]: client 203.88.23.10#41807: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:45:14 server named[2426]: client 203.88.23.9#20092: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:14 server named[2426]: client 203.88.6.10#43526: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:15 server named[2426]: client 203.88.23.9#17173: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:15 server named[2426]: client 203.88.23.9#62412: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:15 server named[2426]: client 203.88.23.10#63961: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:45:15 server named[2426]: client 203.88.23.10#64345: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:45:15 server named[2426]: client 203.88.23.10#31030: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:45:16 server named[2426]: client 203.88.6.9#17098: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:16 server named[2426]: client 203.88.6.9#17197: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:16 server named[2426]: client 203.88.6.9#18114: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:16 server named[2426]: client 203.88.6.9#59138: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:45:17 server named[2426]: client 203.88.6.9#28715: query (cache) 'www.xxxmaza.com/A/IN' denied Jul 1 15:48:33 server named[2426]: client 203.88.23.9#26355: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:48:34 server named[2426]: client 203.88.23.9#34473: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:48:34 server named[2426]: client 203.88.23.9#62658: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:48:34 server named[2426]: client 203.88.23.9#51631: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:48:35 server named[2426]: client 203.88.23.9#54701: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:48:36 server named[2426]: client 203.88.6.10#63694: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:48:36 server named[2426]: client 203.88.6.10#18203: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:48:37 server named[2426]: client 203.88.6.10#9029: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:48:38 server named[2426]: client 203.88.6.10#58981: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:48:38 server named[2426]: client 203.88.6.10#29321: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:49:47 server named[2426]: client 119.160.127.42#42355: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:49:49 server named[2426]: client 119.160.120.42#46285: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:49:53 server named[2426]: client 119.160.120.42#30696: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:49:54 server named[2426]: client 119.160.127.42#14038: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:49:55 server named[2426]: client 119.160.120.42#33586: query (cache) 'xxxmaza.com/A/IN' denied Jul 1 15:49:56 server named[2426]: client 119.160.127.42#55114: query (cache) 'xxxmaza.com/A/IN' denied

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  • SQL SERVER – Beginning of SQL Server Architecture – Terminology – Guest Post

    - by pinaldave
    SQL Server Architecture is a very deep subject. Covering it in a single post is an almost impossible task. However, this subject is very popular topic among beginners and advanced users.  I have requested my friend Anil Kumar who is expert in SQL Domain to help me write  a simple post about Beginning SQL Server Architecture. As stated earlier this subject is very deep subject and in this first article series he has covered basic terminologies. In future article he will explore the subject further down. Anil Kumar Yadav is Trainer, SQL Domain, Koenig Solutions. Koenig is a premier IT training firm that provides several IT certifications, such as Oracle 11g, Server+, RHCA, SQL Server Training, Prince2 Foundation etc. In this Article we will discuss about MS SQL Server architecture. The major components of SQL Server are: Relational Engine Storage Engine SQL OS Now we will discuss and understand each one of them. 1) Relational Engine: Also called as the query processor, Relational Engine includes the components of SQL Server that determine what your query exactly needs to do and the best way to do it. It manages the execution of queries as it requests data from the storage engine and processes the results returned. Different Tasks of Relational Engine: Query Processing Memory Management Thread and Task Management Buffer Management Distributed Query Processing 2) Storage Engine: Storage Engine is responsible for storage and retrieval of the data on to the storage system (Disk, SAN etc.). to understand more, let’s focus on the following diagram. When we talk about any database in SQL server, there are 2 types of files that are created at the disk level – Data file and Log file. Data file physically stores the data in data pages. Log files that are also known as write ahead logs, are used for storing transactions performed on the database. Let’s understand data file and log file in more details: Data File: Data File stores data in the form of Data Page (8KB) and these data pages are logically organized in extents. Extents: Extents are logical units in the database. They are a combination of 8 data pages i.e. 64 KB forms an extent. Extents can be of two types, Mixed and Uniform. Mixed extents hold different types of pages like index, System, Object data etc. On the other hand, Uniform extents are dedicated to only one type. Pages: As we should know what type of data pages can be stored in SQL Server, below mentioned are some of them: Data Page: It holds the data entered by the user but not the data which is of type text, ntext, nvarchar(max), varchar(max), varbinary(max), image and xml data. Index: It stores the index entries. Text/Image: It stores LOB ( Large Object data) like text, ntext, varchar(max), nvarchar(max),  varbinary(max), image and xml data. GAM & SGAM (Global Allocation Map & Shared Global Allocation Map): They are used for saving information related to the allocation of extents. PFS (Page Free Space): Information related to page allocation and unused space available on pages. IAM (Index Allocation Map): Information pertaining to extents that are used by a table or index per allocation unit. BCM (Bulk Changed Map): Keeps information about the extents changed in a Bulk Operation. DCM (Differential Change Map): This is the information of extents that have modified since the last BACKUP DATABASE statement as per allocation unit. Log File: It also known as write ahead log. It stores modification to the database (DML and DDL). Sufficient information is logged to be able to: Roll back transactions if requested Recover the database in case of failure Write Ahead Logging is used to create log entries Transaction logs are written in chronological order in a circular way Truncation policy for logs is based on the recovery model SQL OS: This lies between the host machine (Windows OS) and SQL Server. All the activities performed on database engine are taken care of by SQL OS. It is a highly configurable operating system with powerful API (application programming interface), enabling automatic locality and advanced parallelism. SQL OS provides various operating system services, such as memory management deals with buffer pool, log buffer and deadlock detection using the blocking and locking structure. Other services include exception handling, hosting for external components like Common Language Runtime, CLR etc. I guess this brief article gives you an idea about the various terminologies used related to SQL Server Architecture. In future articles we will explore them further. Guest Author  The author of the article is Anil Kumar Yadav is Trainer, SQL Domain, Koenig Solutions. Koenig is a premier IT training firm that provides several IT certifications, such as Oracle 11g, Server+, RHCA, SQL Server Training, Prince2 Foundation etc. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Security, SQL Server, SQL Tips and Tricks, SQL Training, T SQL, Technology

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  • SQL SERVER – Parsing SSIS Catalog Messages – Notes from the Field #030

    - by Pinal Dave
    [Note from Pinal]: This is a new episode of Notes from the Field series. SQL Server Integration Service (SSIS) is one of the most key essential part of the entire Business Intelligence (BI) story. It is a platform for data integration and workflow applications. The tool may also be used to automate maintenance of SQL Server databases and updates to multidimensional cube data. In this episode of the Notes from the Field series I requested SSIS Expert Andy Leonard to discuss one of the most interesting concepts of SSIS Catalog Messages. There are plenty of interesting and useful information captured in the SSIS catalog and we will learn together how to explore the same. The SSIS Catalog captures a lot of cool information by default. Here’s a query I use to parse messages from the catalog.operation_messages table in the SSISDB database, where the logged messages are stored. This query is set up to parse a default message transmitted by the Lookup Transformation. It’s one of my favorite messages in the SSIS log because it gives me excellent information when I’m tuning SSIS data flows. The message reads similar to: Data Flow Task:Information: The Lookup processed 4485 rows in the cache. The processing time was 0.015 seconds. The cache used 1376895 bytes of memory. The query: USE SSISDB GO DECLARE @MessageSourceType INT = 60 DECLARE @StartOfIDString VARCHAR(100) = 'The Lookup processed ' DECLARE @ProcessingTimeString VARCHAR(100) = 'The processing time was ' DECLARE @CacheUsedString VARCHAR(100) = 'The cache used ' DECLARE @StartOfIDSearchString VARCHAR(100) = '%' + @StartOfIDString + '%' DECLARE @ProcessingTimeSearchString VARCHAR(100) = '%' + @ProcessingTimeString + '%' DECLARE @CacheUsedSearchString VARCHAR(100) = '%' + @CacheUsedString + '%' SELECT operation_id , SUBSTRING(MESSAGE, (PATINDEX(@StartOfIDSearchString,MESSAGE) + LEN(@StartOfIDString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@StartOfIDSearchString,MESSAGE) + LEN(@StartOfIDString) + 1)) - (PATINDEX(@StartOfIDSearchString, MESSAGE) + LEN(@StartOfIDString) + 1))) AS LookupRowsCount , SUBSTRING(MESSAGE, (PATINDEX(@ProcessingTimeSearchString,MESSAGE) + LEN(@ProcessingTimeString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@ProcessingTimeSearchString,MESSAGE) + LEN(@ProcessingTimeString) + 1)) - (PATINDEX(@ProcessingTimeSearchString, MESSAGE) + LEN(@ProcessingTimeString) + 1))) AS LookupProcessingTime , CASE WHEN (CONVERT(numeric(3,3),SUBSTRING(MESSAGE, (PATINDEX(@ProcessingTimeSearchString,MESSAGE) + LEN(@ProcessingTimeString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@ProcessingTimeSearchString,MESSAGE) + LEN(@ProcessingTimeString) + 1)) - (PATINDEX(@ProcessingTimeSearchString, MESSAGE) + LEN(@ProcessingTimeString) + 1))))) = 0 THEN 0 ELSE CONVERT(bigint,SUBSTRING(MESSAGE, (PATINDEX(@StartOfIDSearchString,MESSAGE) + LEN(@StartOfIDString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@StartOfIDSearchString,MESSAGE) + LEN(@StartOfIDString) + 1)) - (PATINDEX(@StartOfIDSearchString, MESSAGE) + LEN(@StartOfIDString) + 1)))) / CONVERT(numeric(3,3),SUBSTRING(MESSAGE, (PATINDEX(@ProcessingTimeSearchString,MESSAGE) + LEN(@ProcessingTimeString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@ProcessingTimeSearchString,MESSAGE) + LEN(@ProcessingTimeString) + 1)) - (PATINDEX(@ProcessingTimeSearchString, MESSAGE) + LEN(@ProcessingTimeString) + 1)))) END AS LookupRowsPerSecond , SUBSTRING(MESSAGE, (PATINDEX(@CacheUsedSearchString,MESSAGE) + LEN(@CacheUsedString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@CacheUsedSearchString,MESSAGE) + LEN(@CacheUsedString) + 1)) - (PATINDEX(@CacheUsedSearchString, MESSAGE) + LEN(@CacheUsedString) + 1))) AS LookupBytesUsed ,CASE WHEN (CONVERT(bigint,SUBSTRING(MESSAGE, (PATINDEX(@StartOfIDSearchString,MESSAGE) + LEN(@StartOfIDString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@StartOfIDSearchString,MESSAGE) + LEN(@StartOfIDString) + 1)) - (PATINDEX(@StartOfIDSearchString, MESSAGE) + LEN(@StartOfIDString) + 1)))))= 0 THEN 0 ELSE CONVERT(bigint,SUBSTRING(MESSAGE, (PATINDEX(@CacheUsedSearchString,MESSAGE) + LEN(@CacheUsedString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@CacheUsedSearchString,MESSAGE) + LEN(@CacheUsedString) + 1)) - (PATINDEX(@CacheUsedSearchString, MESSAGE) + LEN(@CacheUsedString) + 1)))) / CONVERT(bigint,SUBSTRING(MESSAGE, (PATINDEX(@StartOfIDSearchString,MESSAGE) + LEN(@StartOfIDString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@StartOfIDSearchString,MESSAGE) + LEN(@StartOfIDString) + 1)) - (PATINDEX(@StartOfIDSearchString, MESSAGE) + LEN(@StartOfIDString) + 1)))) END AS LookupBytesPerRow FROM [catalog].[operation_messages] WHERE message_source_type = @MessageSourceType AND MESSAGE LIKE @StartOfIDSearchString GO Note that you have to set some parameter values: @MessageSourceType [int] – represents the message source type value from the following results: Value     Description 10           Entry APIs, such as T-SQL and CLR Stored procedures 20           External process used to run package (ISServerExec.exe) 30           Package-level objects 40           Control Flow tasks 50           Control Flow containers 60           Data Flow task 70           Custom execution message Note: Taken from Reza Rad’s (excellent!) helper.MessageSourceType table found here. @StartOfIDString [VarChar(100)] – use this to uniquely identify the message field value you wish to parse. In this case, the string ‘The Lookup processed ‘ identifies all the Lookup Transformation messages I desire to parse. @ProcessingTimeString [VarChar(100)] – this parameter is message-specific. I use this parameter to specifically search the message field value for the beginning of the Lookup Processing Time value. For this execution, I use the string ‘The processing time was ‘. @CacheUsedString [VarChar(100)] – this parameter is also message-specific. I use this parameter to specifically search the message field value for the beginning of the Lookup Cache  Used value. It returns the memory used, in bytes. For this execution, I use the string ‘The cache used ‘. The other parameters are built from variations of the parameters listed above. The query parses the values into text. The string values are converted to numeric values for ratio calculations; LookupRowsPerSecond and LookupBytesPerRow. Since ratios involve division, CASE statements check for denominators that equal 0. Here are the results in an SSMS grid: This is not the only way to retrieve this information. And much of the code lends itself to conversion to functions. If there is interest, I will share the functions in an upcoming post. If you want to get started with SSIS with the help of experts, read more over at Fix Your SQL Server. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Notes from the Field, PostADay, SQL, SQL Authority, SQL Backup and Restore, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: SSIS

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  • Design pattern to handle queries using multiple models

    - by coderkane
    I am presented with a dilemma while trying to re-designing the class structure for my PHP/MySQL application to make it more elegant and conform it to the SOLID principle. The problem goes like this: Let as assume, there is an abstract class called person which has certain properties to define a generic person, such as name, age, date of birth etc. There are two classes, student, and teacher, that implements this abstract class. They add their own unique properties to it. I have designed all the three classes to include all the operational logic (details of which are not relevant in context of the question). Now, I need to create views/reports/data grids which contain details from multiple classes, for example, say, a list of all students doing projects in Chemistry mentored by a teacher whose name is the parameter to the query. This is just one example of a view, there are many different views in the application, which uses data from 3-4 tables, and each of them have multiple input parameters to generate them. Considering this particular example, I have written the relevant query using JOIN and the results are as expected and proper, now here is the dilemma: Keeping in mind the single responsibility principle, where should I keep this query? It does not belong to either Student class, or Teacher class or any other classes currently present. a) Should I create a new class, say dataView class, and design it as a MVC pattern and keep the query there? What about the other views? how do they fit in this architecture? b) Should I not keep the query in code at all, and make it DB View ? c) Am I completely wrong in the approach? If so what is the right approach? My considerations are as follows: a) should be easy to add new views later on if requirement comes, without having to copy-paste-modify code b) would like to make it as loosely coupled as possible so that if minor db structure changes happen, it does not break I did google searches on report design and OOP report generators, but all the result seem to focus on the visual design of the report rather than fetching the data. I have already taken care of the visual aspect of the report using MVC with html templates. I am sure this is a very fundamental problem with known solution, but I am somehow not able to find it (maybe searching with wrong keyword). Edit1: Modified the title to make it more relevant Edit2: The accepted answer got me thinking in the right direction and identify my design flaws, which eventually led me to find this question and the solution in Stack Overflow which gave me the detailed answer to clear the confusion.

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  • SPTI problem with Mode Select

    - by Bob Murphy
    I'm running into a problem in which an attempt to do a "Mode Select" SCSI command using SPTI is returning an error status of 0x02 ("Check Condition"), and hope someone here might have some tips or suggestions. The code in question is intended to work with at a custom SCSI device. I wrote the original support for it using ASPI under WinXP, and am converting it to work with SPTI under 64-bit Windows 7. Here's the problematic code - and what's happening is, sptwb.spt.ScsiStatus is 2, which is a "Check Condition" error. Unfortunately, the device in question doesn't return useful information when you do a "Request Sense" after this problem occurs, so that's no help. void MSSModeSelect(const ModeSelectRequestPacket& inRequest, StatusResponsePacket& outResponse) { IPC_LOG("MSSModeSelect(): PathID=%d, TargetID=%d, LUN=%d", inRequest.m_Device.m_PathId, inRequest.m_Device.m_TargetId, inRequest.m_Device.m_Lun); int adapterIndex = inRequest.m_Device.m_PathId; HANDLE adapterHandle = prvOpenScsiAdapter(inRequest.m_Device.m_PathId); if (adapterHandle == INVALID_HANDLE_VALUE) { outResponse.m_Status = eScsiAdapterErr; return; } SCSI_PASS_THROUGH_WITH_BUFFERS sptwb; memset(&sptwb, 0, sizeof(sptwb)); #define MODESELECT_BUF_SIZE 32 sptwb.spt.Length = sizeof(SCSI_PASS_THROUGH); sptwb.spt.PathId = inRequest.m_Device.m_PathId; sptwb.spt.TargetId = inRequest.m_Device.m_TargetId; sptwb.spt.Lun = inRequest.m_Device.m_Lun; sptwb.spt.CdbLength = CDB6GENERIC_LENGTH; sptwb.spt.SenseInfoLength = 0; sptwb.spt.DataIn = SCSI_IOCTL_DATA_IN; sptwb.spt.DataTransferLength = MODESELECT_BUF_SIZE; sptwb.spt.TimeOutValue = 2; sptwb.spt.DataBufferOffset = offsetof(SCSI_PASS_THROUGH_WITH_BUFFERS,ucDataBuf); sptwb.spt.Cdb[0] = SCSIOP_MODE_SELECT; sptwb.spt.Cdb[4] = MODESELECT_BUF_SIZE; DWORD length = offsetof(SCSI_PASS_THROUGH_WITH_BUFFERS,ucDataBuf) + sptwb.spt.DataTransferLength; memset(sptwb.ucDataBuf, 0, sizeof(sptwb.ucDataBuf)); sptwb.ucDataBuf[2] = 0x10; sptwb.ucDataBuf[16] = (BYTE)0x01; ULONG bytesReturned = 0; BOOL okay = DeviceIoControl(adapterHandle, IOCTL_SCSI_PASS_THROUGH, &sptwb, sizeof(SCSI_PASS_THROUGH), &sptwb, length, &bytesReturned, FALSE); DWORD gle = GetLastError(); IPC_LOG(" DeviceIoControl() %s", okay ? "worked" : "failed"); if (okay) { outResponse.m_Status = (sptwb.spt.ScsiStatus == 0) ? eOk : ePrinterStatusErr; } else { outResponse.m_Status = eScsiPermissionsErr; } CloseHandle(adapterHandle); } A few more remarks, for what it's worth: This is derived from some old ASPI code that does the "Mode Select" flawlessly. This routine opens \\.\SCSI<whatever> at the beginning, via prvOpenScsiAdapter(), and closes the handle at the end. All the other routines for dealing with the device do the same thing, including the routine to do "Reserve Unit". Is this a good idea under SPTI, or should the call to "Reserve Unit" leave the handle open, so this routine and others in the sequence can use the same handle? This uses the IOCTL_SCSI_PASS_THROUGH. Should "Mode Select" use IOCTL_SCSI_PASS_THROUGH_DIRECT instead? Thanks in advance - any help will be greatly appreciated.

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  • Add shortcut SQL management studio 2008 to select top 1000 order by PK desc

    - by JP Hellemons
    Hello, when I right click a table I can select select top 1000 rows and edit top 200 rows I'd like to add an option select bottom 1000 rows I am pretty sure that I've seen it somewhere online how to do this. But I can't remember where... already found this: http://sqlserver-training.com/how-to-change-default-value-of-select-or-edit-top-rows-in-ssms-2008/- but it seems impossible to add a template query...

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  • How does mysql define DISTINCT() in reference documentation

    - by goran
    EDIT: This question is about finding definitive reference to MySQL syntax on SELECT modifying keywords and functions. /EDIT AFAIK SQL defines two uses of DISTINCT keywords - SELECT DISTINCT field... and SELECT COUNT(DISTINCT field) ... However in one of web applications that I administer I've noticed performance issues on queries like SELECT DISTINCT(field1), field2, field3 ... DISTINCT() on a single column makes no sense and I am almost sure it is interpreted as SELECT DISTINCT field1, field2, field3 ... but how can I prove this? I've searched mysql site for a reference on this particular syntax, but could not find any. Does anyone have a link to definition of DISTINCT() in mysql or knows about other authoritative source on this? Best EDIT After asking the same question on mysql forums I learned that while parsing the SQL mysql does not care about whitespace between functions and column names (but I am still missing a reference). As it seems you can have whitespace between functions and the parenthesis SELECT LEFT (field1,1), field2... and get mysql to understand it as SELECT LEFT(field,1) Similarly SELECT DISTINCT(field1), field2... seems to get decomposed to SELECT DISTINCT (field1), field2... and then DISTINCT is taken not as some undefined (or undocumented) function, but as SELECT modifying keyword and the parenthesis around field1 are evaluated as if they were part of field expression. It would be great if someone would have a pointer to documentation where it is stated that the whitespace between functions and parenthesis is not significant or to provide links to apropriate MySQL forums, mailing lists where I could raise a question to put this into reference. EDIT I have found a reference to server option IGNORE SPACE. It states that "The IGNORE SPACE SQL mode can be used to modify how the parser treats function names that are whitespace-sensitive", later on it states that recent versions of mysql have reduced this number from 200 to 30. One of the remaining 30 is COUNT for example. With IGNORE SPACE enabled both SELECT COUNT(*) FROM mytable; SELECT COUNT (*) FROM mytable; are legal. So if this is an exception, I am left to conclude that normally functions ignore space by default. If functions ignore space by default then if the context is ambiguous, such as for the first function on a first item of the select expression, then they are not distinguishable from keywords and the error can not be thrown and MySQL must accept them as keywords. Still, my conclusions feel like they have lot of assumptions, I would still be grateful and accept any pointers to see where to follow up on this.

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  • Is there a fully-functional dropdown replacement for HTML SELECT that works in IE?

    - by Ken Paul
    We determined in a previous question that many features of HTML SELECTs are not supported in IE. Is there an alternative widget that you would recommend from your experience that meets the following requirements? Respects the contentEditable property (does not allow selection changes if true) Respects the disabled property of individual OPTIONs (shows them "grayed out" or with strike-through font, and makes them un-selectable) Supports Option Groups (OPTGROUP elements) Supports style options such as border and margin in the SELECT and all sub-elements Supports dynamic add and delete of OPTION and OPTGROUP elements Supports the above in IE version 6 and above EDIT: As noted by @Joel Coehoorn, items 3 and 5 above are currently supported in IE. They are included here to make sure they are not overlooked in a replacement widget.

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  • SQL Server Table locks in long query - Solution: NoLock?

    - by Kovu
    a report in my application runs a query that needs between 5 - 15 seconds (constrained to count of rows that will be returned). The query has 8 joins to nearly all main-tables of my application (Customers, sales, units etc). A little tool shows me, that in this time, all those 8 tables are locked with a shared table lock. That means, no update operation will be done in this time. A solution from a friend is, to have every join in the query, which is not mandetory to have 100% correct data (dirty read), with a NoLock, so only 1 of this 8 tables will be locked completly. Is that a good solution? For a report in which 99% of data came from one table, unlock the less prio tables?

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  • iPhone facebook connect FQL Query to get Profile URL.

    - by user306641
    Hai. I am using Face book Connect FQL Queries to extract my profile photo url that is src_big,src_small URL. But i am always getting the empty array in below delegate (void)request:(FBRequest*)request didLoad:(id)result My FQL query is. NSString* fql = [NSString stringWithFormat:@"SELECT src_big,src_small FROM photo WHERE pid IN (SELECT cover_pid FROM album WHERE owner =%lld AND name ='Profile Pictures')", session.uid]; NSDictionary* params = [NSDictionary dictionaryWithObject:fql forKey:@"query"]; [[FBRequest requestWithDelegate:self] call:@"facebook.fql.query" params:params]; But - (void)request:(FBRequest*)request didLoad:(id)result always return the empty result. Can any one please correct me if there any mistake.

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  • How do I increase Relevance value in an advanced MySQL query?

    - by morgant
    I've got a MySQL query similar to the following: SELECT *, MATCH (`Description`) AGAINST ('+ipod +touch ' IN BOOLEAN MODE) * 8 + MATCH(`Description`) AGAINST ('ipod touch' IN BOOLEAN MODE) AS Relevance FROM products WHERE ( MATCH (`Description`) AGAINST ('+ipod +touch' IN BOOLEAN MODE) OR MATCH(`LongDescription`) AGAINST ('+ipod +touch' IN BOOLEAN MODE) ) HAVING Relevance > 1 ORDER BY Relevance DESC Now, I've made the query more advanced by also searching for UPC: SELECT *, MATCH (`Description`) AGAINST ('+ipod +touch ' IN BOOLEAN MODE) * 8 + MATCH(`Description`) AGAINST ('ipod touch' IN BOOLEAN MODE) + `UPC` = '123456789012' * 16 AS Relevance FROM products WHERE ( MATCH (`Description`) AGAINST ('+ipod +touch' IN BOOLEAN MODE) OR MATCH(`LongDescription`) AGAINST ('+ipod +touch' IN BOOLEAN MODE) ) AND `UPC` = '123456789012' HAVING Relevance > 1 ORDER BY Relevance DESC That'll return results, but the fact that I had a successful match on the UPC does not increase the value of Relevance. Can I only do that kind of calculation w/full text searches like MATCH() AGAINST()? Clarification: Okay, so my real question is, why does the following not have a Relevance = 16? SELECT `UPC`, `UPC` = '123456789012' * 16 AS Relevance FROM products WHERE `UPC` = '123456789012' HAVING Relevance > 1 ORDER BY Relevance DESC

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  • How to SELECT DISTINCT Info with TOP 1 Info and an Order By FROM the Top 1 Info

    - by Erin Taylor
    I have 2 tables, that look like: CustomerInfo(CustomterID, CustomerName) CustomerReviews(ReviewID, CustomerID, Review, Score) I want to search reviews for a string and return CustomerInfo.CustomerID and CustomerInfo.CustomerName. However, I only want to show distinct CustomerID and CustomerName along with just one of their CustomerReviews.Reviews and CustomerReviews.Score. I also want to order by the CustomerReviews.Score. I can't figure out how to do this, since a customer can leave multiple reviews, but I only want a list of customers with their highest scored review. Any ideas?

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  • How can I Query only __key__ on a Google Appengine PolyModel child?

    - by Gabriel
    So the situation is: I want to optimize my code some for doing counting of records. So I have a parent Model class Base, a PolyModel class Entry, and a child class of Entry Article: How would I query Article.key so I can reduce the query load but only get the Article count. My first thought was to use: q = db.GqlQuery("SELECT __key__ from Article where base = :1", i_base) but it turns out GqlQuery doesn't like that because articles are actually stored in a table called Entry. Would it be possible to Query the class attribute? something like: q = db.GqlQuery("select __key__ from Entry where base = :1 and :2 in class", i_base, 'Article') neither of which work. Turns out the answer is even easier. But I am going to finish this question because I looked everywhere for this. q = db.GqlQuery("select __key__ from Entry where base = :1 and class = :2", i_base, 'Article')

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  • How to select latest change done in the given Table structure?

    - by OM The Eternity
    I have a Table structure as id, trackid, table_name, operation, oldvalue, newvalue, field, changedonetime Now if I have 3 rows for the same "trackid" same "field", then how can i select the latest out of the three? i.e. for e.g.: id = 100 trackid = 152 table_name = jos_menu operation= UPDATE oldvalue = IPL newvalue = IPLcccc field = name live = 0 changedonetime = 2010-04-30 17:54:39 and id = 101 trackid = 152 table_name = jos_menu operation= UPDATE oldvalue = IPLcccc newvalue = IPL2222 field = name live = 0 changedonetime = 2010-04-30 18:54:39 As u can see above the secind entry is the latest change, Now what query I shoud use to get the only one and Latest row out of many such rows...

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  • Access is refusing to run an query with linked table?

    - by Mahmoud
    Hey all i have 3 tables each as follow cash_credit Bank_Name-------in_date-------Com_Id---Amount America Bank 15/05/2010 1 200 HSBC 17/05/2010 3 500 Cheque_credit Bank_Name-----Cheque_Number-----in_date-------Com_Id---Amount America Bank 74835435-5435 15/05/2010 2 600 HSBC 41415454-2851 17/05/2010 5 100 Companies com_id----Com_Name 1 Ebay 2 Google 3 Facebook 4 Amazon Companies table is a linked table when i tried to create an query as follow SELECT cash_credit.Amount, Companies.Com_Name, cheque_credit.Amount FROM cheque_credit INNER JOIN (cash_credit INNER JOIN Companies ON cash_credit.com_id = Companies.com_id) ON cheque_credit.com_id = Companies.com_id; I get an error saying that my inner Join is incorrectly, this query was created using Access 2007 query design the error is Type mismatch in expression then i thought it might be the inner join so i tried Left Join and i get an error that this method is not used JOIN expression is not supported I am confused on where is the problem that is causing all this

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  • How to check whether a mysql select statement result has a value or not in php?

    - by udaya
    I have a textbox UserName and a Check Availability button next to it..... I have checked the availability by passing UserName textbox value..... But it doesn't seem to work.... Here is what i am doing? echo $UserName = $_GET['CheckUsername']; $_SESSION['state'] = $State; $queryres = "SELECT dUser_name FROM tbl_login WHERE dUser_name='$UserName'"; $result = mysql_query($queryres,$cn) or die("Selection Query Failed !!!"); if($result==true) // this condition doesn't seem to work { echo "User Name Available"; } else { echo "Sorry user name taken"; }

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  • SQL - Please Help - How can I select values from different rows depending on the most recent entry

    - by user321185
    Hiya, Basically I have a table which is used to hold employee work wear details. It is formed of the columns: EmployeeID, CostCentre, AssociateLevel, IssueDate, TrouserSize, TrouserLength, TopSize & ShoeSize. An employee can be assigned a pair of trousers, a top and shoes at the same time or only one or two pieces of clothing. As we all know sepeoples sizes and employee levels can change which is why I need help really. I need to be able to select the most recent clothes size and associate level for each item of clothing for each employee. So for example if employee '54664LSS' was given a pair of 'XL' trousers and a 'L' top on 24/03/11 but then received a 'M' top on 26/05/10. Then the values of the 'M' sized top and the 'L' sized trousers would need to be returned. Any help would be greatly appreciated as I'm pretty stuck :(. Thanks.

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  • How to run a progress-bar through an insert query?

    - by Gold
    I have this insert query: try { Cmd.CommandText = @"INSERT INTO BarcodTbl SELECT * FROM [Text;DATABASE=" + PathI + @"\].[Tmp.txt];"; Cmd.ExecuteNonQuery(); Cmd.Dispose(); } catch (Exception ex) { MessageBox.Show(ex.Message); } I have two questions: How can I run a progress-bar from the beginning to the end of the insert? If there is an error, I got the error exception and the action will stop - the query stops and the BarcodTbl is empty. How I can see the error and allow the query to continue filling the table?

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  • SQL SERVER – Concat Function in SQL Server – SQL Concatenation

    - by pinaldave
    Earlier this week, I was delivering Advanced BI training on the subject of “SQL Server 2008 R2″. I had great time delivering the session. During the session, we talked about SQL Server 2010 Denali. Suddenly one of the attendees suggested his displeasure for the product. He said, even though, SQL Server is now in moving very fast and have proved many times a good enterprise solution, it does not have some basic functions. I naturally asked him for example and he suggested CONCAT() which exists in MySQL and Oracle. The answer is very simple – the equalent function in SQL Server to CONCAT() is ‘+’ (plus operator without quotes). Method 1: Concatenating two strings SELECT 'FirstName' + ' ' + 'LastName' AS FullName Method 2: Concatenating two Numbers SELECT CAST(1 AS VARCHAR(10)) + 'R' + CAST(2 AS VARCHAR(10)) Method 3: Concatenating values from table columns SELECT FirstName + ' ' + LastName FROM AdventureWorks.Person.Contact Well, this may look very simple but sometime it is very difficult to find the information for simple things only. Do you have any such example which you would like to share with community? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL String, SQL Tips and Tricks, T SQL, Technology

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