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  • Update table with index is too slow

    - by pauloya
    Hi, I was watching the Profiler on a live system of our application and I saw that there was an update instruction that we run periodically (every second) that was quite slow. It took around 400ms every time. The query includes this update (which is the slow part) UPDATE BufferTable SET LrbCount = LrbCount + 1, LrbUpdated = getdate() WHERE LrbId = @LrbId This is the table CREATE TABLE BufferTable( LrbId [bigint] IDENTITY(1,1) NOT NULL, ... LrbInserted [datetime] NOT NULL, LrbProcessed [bit] NOT NULL, LrbUpdated [datetime] NOT NULL, LrbCount [tinyint] NOT NULL, ) The table has 2 indexes (non unique and non clustered) with the fields by this order: * Index1 - (LrbProcessed, LrbCount) * Index2 - (LrbInserted, LrbCount, LrbProcessed) When I looked at this I thought that the problem would come from Index1 since LrbCount is changing a lot and it changes the order of the data in the index. But after desactivating index1 I saw the query was taking the same time as initially. Then I rebuilt index1 and desactivated index2, this time the query was very fast. It seems to me that Index2 should be faster to update, the order of the data shouldn't change since the LrbInserted time is not changed. Can someone explain why index2 is much heavier to update then index1? Thank you!

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  • mysql count(*) left join group by - the number of files in a folder

    - by Flavius
    Hi I have the following tables CREATE TABLE `files` ( `fileid` int(11) NOT NULL AUTO_INCREMENT, `filename` varchar(255) NOT NULL, `filesize` int(11) NOT NULL, `folder` int(11) NOT NULL, PRIMARY KEY (`fileid`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; CREATE TABLE `folders` ( `directoryid` int(11) NOT NULL AUTO_INCREMENT, `directoryname` varchar(255) NOT NULL, PRIMARY KEY (`directoryid`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; How to get a list of all folders and the number of files they hold, including folders who have no (zero) files? Recursion must not be taken into account. Found it select folders.directoryid, folders.directoryname, count(files.fileid) as no_files from folders left join files on files.folder = folders.directoryid group by folders.directoryid, folders.directoryname I hope it will help someone.

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  • Selecting distinct values from mysql with largest timestamp

    - by user987048
    I am building a mail system. The inbox is only supposed to grab the last message (one with the highest time value) of a concatenation of user and sender, where the user or sender is the user ID. Here is the table structure: CREATE TABLE IF NOT EXISTS `mail` ( `user` int(11) NOT NULL, `sender` int(11) NOT NULL, `body` text NOT NULL, `new` enum('0','1') NOT NULL default '1', `time` int(11) NOT NULL, KEY `user` (`user`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; So, with a table with the following data: user sender new time ***************************************** 1 0 0 5 1 0 0 6 2 1 0 7 1 0 1 8 1 2 0 9 1 0 1 11 1 2 1 12 I want to select the following: WHERE USER OR SENDER = X (in this case, 1) user sender new time ***************************************** 2 1 0 7 1 2 0 9 1 0 1 11 How would I go about doing something like this?

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  • Help needed for writing a Set Based query for finding the highest marks obtained by the students

    - by priyanka.sarkar_2
    I have the below table declare @t table (id int identity, name varchar(50),sub1 int,sub2 int,sub3 int,sub4 int) insert into @t select 'name1',20,30,40,50 union all select 'name2',10,30,40,50 union all select 'name3',40,60,100,50 union all select 'name4',80,30,40,80 union all select 'name5',80,70,40,50 union all select 'name6',10,30,40,80 The desired output should be Id Name Sub1 Sub2 Sub3 Sub4 3 Name3 100 4 Name4 80 80 5 Name5 80 70 6 Name6 80 What I have done so far is ;with cteSub1 as ( select rn1 = dense_rank() over(order by sub1 desc),t.id,t.name,t.sub1 from @t t ) ,cteSub2 as ( select rn2 = dense_rank() over(order by sub2 desc),t.id,t.name,t.sub2 from @t t ) ,cteSub3 as ( select rn3 = dense_rank() over(order by sub3 desc),t.id,t.name,t.sub3 from @t t ) ,cteSub4 as ( select rn4 = dense_rank() over(order by sub4 desc),t.id,t.name,t.sub4 from @t t ) select x1.id,x2.id,x3.id,x4.id ,x1.sub1,x2.sub2,x3.sub3,x4.sub4 from (select c1.id,c1.sub1 from cteSub1 c1 where rn1 =1) as x1 full join (select c2.id,c2.sub2 from cteSub2 c2 where rn2 =1)x2 on x1.id = x2.id full join (select c3.id,c3.sub3 from cteSub3 c3 where rn3 =1)x3 on x1.id = x3.id full join (select c4.id,c4.sub4 from cteSub4 c4 where rn4 =1)x4 on x1.id = x4.id which is giving me the output as id id id id sub1 sub2 sub3 sub4 5 5 NULL NULL 80 70 NULL NULL 4 NULL NULL 4 80 NULL NULL 80 NULL NULL 3 NULL NULL NULL 100 NULL NULL NULL NULL 6 NULL NULL NULL 80 Help needed. Also how can I reduce the number of CTE's?

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  • filter by atributs php script

    - by cosy
    I have the table : id id_products id_atribut name value 1 13 8 autdio 2.1 2 13 9 hdd 200 Gb 3 13 10 cd-rom 2 4 20 8 audio 2.1 the problem is, how can i select from this table where id_products=13 and name="audio" and value="2.1" and name="hdd" and value="200 gb" .... How can i do this?

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  • Forcing the use of an index can improve performance?

    - by aF.
    Imagine that we have a query like this: select a.col1, b.col2 from t1 a inner join t2 b on a.col1 = b.col2 where a.col1 = 'abc' Both col1 and col2 don't have any index. If I add another restriction on the where clause, one that is always correct but with a column with an index: select a.col1, b.col2 from t1 a inner join t2 b on a.col1 = b.col2 where a.col1 = 'abc' and a.id >= 0 -- column always true and with index May the query perform faster since it may use the index on id column?

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  • Multiple/Sub quries with codeigniter

    - by user1011713
    I just started with Codeigniter and this is driving me nuts. I have a query that determines whether a user has bought any programs. I then have to use that program's type category to run and determine how many times he or she has recorded a query in another table. Sorry for the confusion but the code hopefully makes sense. I'm having problem returning the two arrays from my Model to my Controller to onto the view obviously. function specificPrograms() { $specific_sql = $this->db->query("SELECT program,created FROM `assessment` WHERE uid = $this->uid"); if($specific_sql->num_rows() > 0) { foreach ($specific_sql->result() as $specific) { $data[] = $specific; $this->type = $specific->program; } return $data; } $sub_sql = $this->db->query("SELECT id FROM othertable WHERE user_id_fk = $this->uid and type = '$this->type'"); if($sub_sql->num_rows() > 0) { foreach ($sub_sql->result() as $otherp) { $data[] = $otherp; } return $data; } } Then in my Controller I have, $data['specific'] = $this->user_model->specificPrograms(); $data['otherp'] = $this->user_model->specificPrograms(); Thanks for any help.

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  • need to read data from oracle database with many conditions

    - by randeepsp
    hi! i have 3 tables A,B and C. table A has column employee_name,id table B is the main table and has columns id,os version. table c has the columns id,package id and package version. i want to query the count of employee_name where the id of table a and c are matched with id of table b(which is the main table). i should also get the names of employees grouped by the os version they have and also the package version.

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  • Query to bring count from comma seperated Value

    - by Mugil
    I have Two Tables One for Storing Products and Other for Storing Orders List. CREATE TABLE ProductsList(ProductId INT NOT NULL PRIMARY KEY, ProductName VARCHAR(50)) INSERT INTO ProductsList(ProductId, ProductName) VALUES(1,'Product A'), (2,'Product B'), (3,'Product C'), (4,'Product D'), (5,'Product E'), (6,'Product F'), (7,'Product G'), (8,'Product H'), (9,'Product I'), (10,'Product J'); CREATE TABLE OrderList(OrderId INT NOT NULL PRIMARY KEY AUTO_INCREMENT, EmailId VARCHAR(50), CSVProductIds VARCHAR(50)) SELECT * FROM OrderList INSERT INTO OrderList(EmailId, CSVProductIds) VALUES('[email protected]', '2,4,1,5,7'), ('[email protected]', '5,7,4'), ('[email protected]', '2'), ('[email protected]', '8,9'), ('[email protected]', '4,5,9'), ('[email protected]', '1,2,3'), ('[email protected]', '9,10'), ('[email protected]', '1,5'); Output ItemName NoOfOrders Product A 4 Product B 3 Product C 1 Product D 3 Product E 4 Product F 0 Product G 2 Product H 1 Product I 2 Product J 1 The Order List Stores the ItemsId as Comma separated value for every customer who places order.Like this i am having more than 40k Records in my dB table Now I am assigned with a task of creating report in which I should display Items and No of People ordered Items as Shown Below I Used Query as below in my PHP to bring the Orders One By One and storing in array. SELECT COUNT(PL.EmailId) FROM OrderList PL WHERE CSVProductIds LIKE '2' OR CSVProductIds LIKE '%,2,%' OR CSVProductIds LIKE '%,2' OR CSVProductIds LIKE '2,%'; 1.Is it possible to get the same out put by using Single Query 2.Does using a like in mysql query slows down the dB when the table has more no of records i.e 40k rows

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  • Copying Primary key to another field in Access.

    - by BashLover
    Hey, I'm struggling to copy the Primary Key to another field in Access. This is irrelevant , but clarifying on what I'm comparing. ... WHERE Tunniste=" & [Tarkiste] & "" Tunniste = Primary Key , Autonumber , ID (Generated by Access.) Tarkiste = This is the field I want to copy it to compare it. I'm open to suggestions, I've already try'ed with Form_Load, using the following code. Private Sub Form_Load() DoCmd.RunSQL "UPDATE Korut SET [Tarkiste]=('" & Tunniste & "');" End Sub But this copied the same key to all the entries in "Tarkiste" field. In simplicity I want 1:1 copy of field "Tunniste" to "Tarkiste" , whichever method it takes. Started from this question. File Picker Replaces All Rows With The Same Choice.

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  • How does linq decide between inner & outer joins

    - by user287795
    Hi Usually linq is using an left outer join for its queries but on some cases it decides to use inner join instead. I have a situation where that decision results in wrong results since the second table doesn't always have suitable records and that removes the records from the first table. I'm using a linqdatasource over a dbml where the relevant tables are identical but one holds historical records removed from the first. both have the same primary key. and I'm using a dataloadoption to load both tables at once with out round trips. Would you explain why linq decided to use an inner join here? Thanks

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  • help with sql query - in access 2007

    - by Gold
    hi i have 2 tables table items has 144602 records table A has 27721 records code in items = BAR8 in A i want to show all records that equal i try this: SELECT Items.Code, A.BAR8 FROM Items INNER JOIN A ON Items.Code = A.BAR8; and i get 28048 records !!! i need to get 27721 , how to do it ? thank's in advance

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  • Query returning an ascending group number

    - by Dougman
    I have a query like below that has groups (COL1) and that group's values (COL2). select col1, col2 from (select 'A' col1, 1 col2 from dual union all select 'A' col1, 2 col2 from dual union all select 'B' col1, 1 col2 from dual union all select 'B' col1, 2 col2 from dual union all select 'C' col1, 1 col2 from dual union all select 'C' col1, 2 col2 from dual ) order by col1, col2; The output of this query looks like: COL1 COL2 ---- ---- A 1 A 2 B 1 B 2 C 1 C 2 What I need is a query that will return an ordered number increasing for each different group (COL1). It seems like there would be a simple way to accomplish this (maybe with analytics) but for some reason it is escaping me. GRPNUM COL1 COL2 ------ ---- ---- 1 A 1 1 A 2 2 B 1 2 B 2 3 C 1 3 C 2 I am running Oracle 10gR2.

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  • IS NULL vs = NULL in where clause + MSSQL

    - by Nev_Rahd
    Hello How to check a value IS NULL [or] = @param (where @param is null) Ex: Select column1 from Table1 where column2 IS NULL = works fine If I want to replace comparing value (IS NULL) with @param. How can this be done Select column1 from Table1 where column2 = @param = this works fine until @param got some value in it and if is null never finds a record. How can this achieve?

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  • wanted to get all dates in mysql result

    - by PankajK
    I have mysql table called user(id, name, join_on) join on is a date field what I want is to show in each day how many uses has been created I can use group by but it will only give me the dates when users get added like if date 4/12/10 5 users added 4/13/10 2 users added 4/15/10 7 users added here date 4/14/10 is missing and I want listing of all dates in one month. I have one solution for it by creating another table only for adding date and that table will left join my users table on join_on and will give total result but I don't want to do that as for creating that I need to create and add entries in date table please suggest the different approach for doing so. Thank you.

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  • difference between where and nested queries

    - by Chris H
    I'm not able to figure out the difference between these queries. I'm pretty sure that the first one is an equi-join. I'm not sure how the second one ISN'T the same as the first. The sub query in #2 selects all Ids from S, and then it returns all R's that also have those ID's, no? SELECT R.cname FROM R, S, WHERE R.Id = S.Id SELECT R.cname FROM R WHERE R.Id IN (SELECT S.Id FROM S)

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  • Problem with sending "SetCookie" first in php code

    - by Camran
    According to this manual: http://us2.php.net/setcookie I have to set the cookie before anything else. Here is my cookie code: if (isset($_COOKIE['watched_ads'])){ $expir = time()+1728000; //20 days $ad_arr = unserialize($_COOKIE['watched_ads']); $arr_elem = count($ad_arr); if (in_array($ad_id, $ad_arr) == FALSE){ if ($arr_elem>10){ array_shift($ad_arr); } $ad_arr[]=$ad_id; setcookie('watched_ads', serialize($ad_arr), $expir, '/'); } } else { $expir = time()+1728000; //20 days $ad_arr[] = $ad_id; setcookie('watched_ads', serialize($ad_arr), $expir, '/'); } As you can see I am using variables in setting the cookie. The variables comes from a mysql_query and I have to do the query first. But then, if I do, I will get an error message: Cannot modify header information - headers already sent by ... The error points to the line where I set the cookie above. What should I do?a

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  • sDesigning a database with flexible user profile

    - by Mughrabi
    I am working on a design where I can have flexible attributes for users and I am confused how to continue the design of the schema. I made a table where I kept system needed information: Table name: users id username password Now, I wish to create a profile table and have one to one relation where all the other attributes in profile table such as email, first name, last name, etc. My question is: is there a way to add a third table in which profiles will be flexible? In other words, if my clients need to create a new attribute he/she won't need any customization to the code.

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