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  • Mysql slow query: INNER JOIN + ORDER BY causes filesort

    - by Alexander
    Hello! I'm trying to optimize this query: SELECT `posts`.* FROM `posts` INNER JOIN `posts_tags` ON `posts`.id = `posts_tags`.post_id WHERE (((`posts_tags`.tag_id = 1))) ORDER BY posts.created_at DESC; The size of tables is 38k rows, and 31k and mysql uses "filesort" so it gets pretty slow. I tried to use different indexes, no luck. CREATE TABLE `posts` ( `id` int(11) NOT NULL auto_increment, `created_at` datetime default NULL, PRIMARY KEY (`id`), KEY `index_posts_on_created_at` (`created_at`), KEY `for_tags` (`trashed`,`published`,`clan_private`,`created_at`) ) ENGINE=InnoDB AUTO_INCREMENT=44390 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci CREATE TABLE `posts_tags` ( `id` int(11) NOT NULL auto_increment, `post_id` int(11) default NULL, `tag_id` int(11) default NULL, `created_at` datetime default NULL, `updated_at` datetime default NULL, PRIMARY KEY (`id`), KEY `index_posts_tags_on_post_id_and_tag_id` (`post_id`,`tag_id`) ) ENGINE=InnoDB AUTO_INCREMENT=63175 DEFAULT CHARSET=utf8 +----+-------------+------------+--------+--------------------------+--------------------------+---------+---------------------+-------+-----------------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+------------+--------+--------------------------+--------------------------+---------+---------------------+-------+-----------------------------------------------------------+ | 1 | SIMPLE | posts_tags | index | index_post_id_and_tag_id | index_post_id_and_tag_id | 10 | NULL | 24159 | Using where; Using index; Using temporary; Using filesort | | 1 | SIMPLE | posts | eq_ref | PRIMARY | PRIMARY | 4 | .posts_tags.post_id | 1 | | +----+-------------+------------+--------+--------------------------+--------------------------+---------+---------------------+-------+-----------------------------------------------------------+ 2 rows in set (0.00 sec) What kind of index I need to define to avoid mysql using filesort? Is it possible when order field is not in where clause?

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  • sql UPDATE, a calculation is used multiple times, can it just be calculated once?

    - by Zachery Delafosse
    UPDATE `play` SET `counter1` = `counter1` + LEAST(`maxchange`, FLOOR(`x` / `y`) ), `counter2` = `counter2` - LEAST(`maxchange`, FLOOR(`x` / `y`) ), `x` = MOD(`x`, `y`) WHERE `x` `y` AND `maxchange` 0 As you can see, " LEAST(`maxchange`, FLOOR(`x` / `y`) ) " is used multiple times, but it should always have the same value. Is there a way to optimize this, to only calculate once? I'm coding this in PHP, for the record.

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  • How to fix this simple SQL query?

    - by morpheous
    I have a database with three tables: user_table country_table city_table I want to write ANSI SQL which will allow me to fetch all the user data (i.e. user details including the name of the country of the last school and the name of the city they live in now). The problem I am having is that I have to use a self join, and I am getting slightly confused. The schema is shown below: CREATE TABLE user_table (id int, first_name varchar(16), last_school_country_id int, city_id int); CREATE TABLE country_table (id int, name varchar(32)); CREATE TABLE city_table (id int, country_id int, name varchar(32)); This is the query I have come up with so far, but the results are wrong, and sometimes, the db engine (mySQL), asks me if I want to show all [HUGE NUMBER HERE] results - which makes me suspect that I am unintentionally creating a cartesian product somewhere. Can someone explain what is wrong with this SQL statement, and what I need to do to fix it? SELECT usr.id AS id, usr.first_name, ctry1.name as loc_country_name, ctry2.name as school_country_name, city.name as loc_city_name FROM user_table usr, country_table ctry1, country_table ctry2, city_table city WHERE usr.last_school_country_id=ctry2.id AND usr.city_id=city.id AND city.country_id=ctry1.id AND ctry1.id=ctry2.id;

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  • How to check with PHP does a SQL database already have

    - by Dan Horvat
    I've tried to find the answer to this question but none of the answers fit. I have two databases, one has 15.000.000 entries and I want to extract the necessary data and store it in a much smaller database with around 33.000 entries. Both databases are open at the same time. Or at least they should be. While having the big database open and extracting the entries from it, is it possible to check whether the value already exists in the smaller database? I just need some generic way which checks that.

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  • How do I strip multiple (optional) parts of a SQL string using .NET Regular Expressions?

    - by Luc
    I've been working on this for a few hours now and can't find any help on it. Basically, I'm trying to strip a SQL string into various parts (fields, from, where, having, groupBy, orderBy). I refuse to believe that I'm the first person to ever try to do this, so I'd like to ask for some advise from the StackOverflow community. :) To understand what I need, assume the following SQL string: select * from table1 inner join table2 on table1.id = table2.id where field1 = 'sam' having table1.field3 > 0 group by table1.field4 order by table1.field5 I created a regular expression to group the parts accordingly: select\s+(?<fields>.+)\s+from\s+(?<from>.+)\s+where\s+(?<where>.+)\s+having\s+(?<having>.+)\s+group\sby\s+(?<groupby>.+)\s+order\sby\s+(?<orderby>.+) This gives me the following results: fields => * from => table1 inner join table2 on table1.id = table2.id where => field1 = 'sam' having => table1.field3 > 0 groupby => table1.field4 orderby => table1.field5 The problem that I'm faced with is that if any part of the SQL string is missing after the 'from' clause, the regular expression doesn't match. To fix that, I've tried putting each optional part in it's own (...)? group but that doesn't work. It simply put all the optional parts (where, having, groupBy, and orderBy) into the 'from' group. Any ideas?

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  • Need help with a SELECT statement

    - by Travis
    I express the relationship between records and searchtags that can be attached to records like so: TABLE RECORDS id name TABLE SEARCHTAGS id recordid name I want to be able to SELECT records based on the searchtags that they have. For example, I want to be able to SELECT all records that have searchtags: (1 OR 2 OR 5) AND (6 OR 7) AND (10) Using the above data structure, I am uncertain how to structure the SQL to accomplish this. Any suggestions? Thanks!

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  • Mysql Avg function for recent 15 records by date (order date desc) in every symbol

    - by venkatesh
    i am trying to create a statement in sql (for a table which holds stock symbols and price on specified date) with avg of 5 day price and avg of 15 days price for each symbol. table description: symbol open high close date the average price is calculated from last 5 days and last 15 days. i tried this for getting 1 symbol: SELECT avg(close), avg(`trd_qty`) FROM (select * from cashmarket WHERE symbol = \'hdil\' order by `M_day` desc limit 0,15 ) s ...but I couldn't get the desired the list for showing avg values for all symbols.

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  • iPhone Core Data - Access deep attributes with to many relationships

    - by ncohen
    Hi everyone, Let say I have an entity user which has a one to many relationship with the entity menu which has a one to many relationship with the entity meal which has a many to one relationship with the entity recipe which has a one to many relationship with the entity element. What I would like to do is to select the elements which belong to a particular user (username = myUsername) and particular menu*s* (minDate < menu.date < maxDate). Does anyone have an idea how to get them? Thanks

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  • Translate SQL to NHibernate Query

    - by Thad
    I have a SQL query that I would like to translate to nhibernate criteria, but I have not found a way to generate the MatchCount field. I tried adding it using a sqlprojection but I could not find a place to set the parameters. SELECT (CASE WHEN LEFT([FirstName], LEN(@Text0)) = @Text0 OR LEFT([FirstName], LEN(@Text1)) = @Text1 OR LEFT([FirstName], LEN(@Text2)) = @Text2 THEN 1 ELSE 0 END + CASE WHEN LEFT([LastName], LEN(@Text0)) = @Text0 OR LEFT([LastName], LEN(@Text1)) = @Text1 OR LEFT([LastName], LEN(@Text2)) = @Text2 THEN 1 ELSE 0 END + CASE WHEN LEFT([PreferredName], LEN(@Text0)) = @Text0 OR LEFT([PreferredName], LEN(@Text1)) = @Text1 OR LEFT([PreferredName], LEN(@Text2)) = @Text2 THEN 1 ELSE 0 END) AS MatchCount , * FROM [client].[Individual] WHERE ( [FirstName] LIKE @Text0 + '%' OR [FirstName] LIKE @Text1 + '%' OR [FirstName] LIKE @Text2 + '%' OR [LastName] LIKE @Text0 + '%' OR [LastName] LIKE @Text1 + '%' OR [LastName] LIKE @Text2 + '%' OR [PreferredName] LIKE @Text0 + '%' OR [PreferredName] LIKE @Text1 + '%' OR [PreferredName] LIKE @Text2 + '%' ) ORDER BY (CASE WHEN LEFT([FirstName], LEN(@Text0)) = @Text0 OR LEFT([FirstName], LEN(@Text1)) = @Text1 OR LEFT([FirstName], LEN(@Text2)) = @Text2 THEN 1 ELSE 0 END + CASE WHEN LEFT([LastName], LEN(@Text0)) = @Text0 OR LEFT([LastName], LEN(@Text1)) = @Text1 OR LEFT([LastName], LEN(@Text2)) = @Text2 THEN 1 ELSE 0 END + CASE WHEN LEFT([PreferredName], LEN(@Text0)) = @Text0 OR LEFT([PreferredName], LEN(@Text1)) = @Text1 OR LEFT([PreferredName], LEN(@Text2)) = @Text2 THEN 1 ELSE 0 END) DESC And yes, this is a ugly statement. Hate having a sql statement in the middle of everthing. Note: There is paging involved and I would prefer not returning all the data to the app server before cutting it down.

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  • convert SQL Server StoredPorcedure to MySql

    - by karthik
    I need to covert the following SP of SQL Server To MySql. I am new to MySql.. Help needed. CREATE PROC InsertGenerator (@tableName varchar(100)) as --Declare a cursor to retrieve column specific information --for the specified table DECLARE cursCol CURSOR FAST_FORWARD FOR SELECT column_name,data_type FROM information_schema.columns WHERE table_name = @tableName OPEN cursCol DECLARE @string nvarchar(3000) --for storing the first half --of INSERT statement DECLARE @stringData nvarchar(3000) --for storing the data --(VALUES) related statement DECLARE @dataType nvarchar(1000) --data types returned --for respective columns SET @string='INSERT '+@tableName+'(' SET @stringData='' DECLARE @colName nvarchar(50) FETCH NEXT FROM cursCol INTO @colName,@dataType IF @@fetch_status<>0 begin print 'Table '+@tableName+' not found, processing skipped.' close curscol deallocate curscol return END WHILE @@FETCH_STATUS=0 BEGIN IF @dataType in ('varchar','char','nchar','nvarchar') BEGIN SET @stringData=@stringData+'''''''''+ isnull('+@colName+','''')+'''''',''+' END ELSE if @dataType in ('text','ntext') --if the datatype --is text or something else BEGIN SET @stringData=@stringData+'''''''''+ isnull(cast('+@colName+' as varchar(2000)),'''')+'''''',''+' END ELSE IF @dataType = 'money' --because money doesn't get converted --from varchar implicitly BEGIN SET @stringData=@stringData+'''convert(money,''''''+ isnull(cast('+@colName+' as varchar(200)),''0.0000'')+''''''),''+' END ELSE IF @dataType='datetime' BEGIN SET @stringData=@stringData+'''convert(datetime,''''''+ isnull(cast('+@colName+' as varchar(200)),''0'')+''''''),''+' END ELSE IF @dataType='image' BEGIN SET @stringData=@stringData+'''''''''+ isnull(cast(convert(varbinary,'+@colName+') as varchar(6)),''0'')+'''''',''+' END ELSE --presuming the data type is int,bit,numeric,decimal BEGIN SET @stringData=@stringData+'''''''''+ isnull(cast('+@colName+' as varchar(200)),''0'')+'''''',''+' END SET @string=@string+@colName+',' FETCH NEXT FROM cursCol INTO @colName,@dataType END

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  • Get the count of A -> B and B->A without duplicates

    - by TomGasson
    I have a table like so: index|from | to ------------------ 1 | ABC | DEF 2 | ABC | GHI 3 | ABC | GHI 4 | ABC | JKL 5 | ABC | JKL 6 | ABC | JKL 7 | DEF | ABC 8 | DEF | GHI 9 | DEF | JKL 10 | GHI | ABC 11 | GHI | ABC 12 | GHI | ABC 13 | JKL | DEF And I need to count how the total times between the points (regardless of direction) to get the result: A | B | count ----------------- ABC | DEF | 2 ABC | GHI | 5 ABC | JKL | 3 DEF | GHI | 1 DEF | JKL | 2 So far I can get: SELECT `a`.`from` as `A`, `a`.`to` as `B`, (`a`.`count` + `b`.`count`) as `count` FROM (SELECT `from`, `to`, count(*) as `count` FROM `table` GROUP BY 1,2) `a` LEFT OUTER JOIN (SELECT `from`,`to`, count(*) as `count` FROM `table` GROUP BY 1,2) `b` ON `a`.`from` = `b`.`to` AND `a`.`to` = `b`.`from` But I'm unsure how to remove the A/B swapped duplicates.

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  • How to update records based on sum of a field then use the sum to calc a new value in sql

    - by Casey
    Below is what i'm trying to do with by iterating through the records. I would like to have a more elegant solution if possible since i'm sure this is not the best way to do it in sql. set @counter = 1 declare @totalhrs dec(9,3), @lastemp char(7), @othrs dec(9,3) while @counter <= @maxrecs begin if exists(select emp_num from #tt_trans where id = @counter) begin set @nhrs = 0 set @othrs = 0 select @empnum = emp_num, @nhrs = n_hrs, @othrs = ot_hrs from #tt_trans where id = @counter if @empnum = @lastemp begin set @totalhrs = @totalhrs + @nhrs if @totalhrs > 40 begin set @othrs = @othrs + @totalhrs - 40 set @nhrs = @nhrs - (@totalhrs - 40) set @totalhrs = 40 end end else begin set @totalhrs = @nhrs set @lastemp = @empnum end update #tt_trans set n_hrs = @nhrs, ot_hrs = @othrs where id = @counter and can_have_ot = 1 end set @counter = @counter + 1 end Thx

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  • In Excel 2010, how can I show a count of occurrences on a specific date within multiple time ranges?

    - by Justin
    Here's what I'm trying to do. I have three columns of data. ID, Date(MM/DD/YY), Time(00:00). I need to create a chart or table that shows the number of occurrences on, say, 12/10/2010 between 00:00 and 00:59, 1:00 and 1:59, etc, for each hour of the day. I can do countif and get results for the date, but I cannot figure out how to show a summary of the count of occurrences per hour for the 24 hour period. I have months of data and many times each day. Example of data set is below. Any help is greatly ID Date Time 221 12/10/2010 00:01 223 12/10/2010 00:45 227 12/10/2010 01:13 334 12/11/2010 14:45 I would like the results to read: Date Time Count 12/10/2010 00:00AM - 00:59AM 2 12/10/2010 01:00AM - 01:59AM 1 12/10/2010 02:00AM - 02:59AM 0 ......(continues for every hour of the day) 12/11/2010 00:00AM - 00:59AM 0 ......... 12/11/2010 14:00PM - 14:59PM 1 And so on. Sorry for the length but I wanted to be clear. EDIT Here is a sample spreadsheet. Very little data, but I couldn't figure out a better way without having a huge file. Tested in notepad for formatting and worked ok on import as csv. PID,Date,Time 2888759,12/10/2010,0:10 2888760,12/10/2010,0:10 2888761,12/10/2010,0:10 2888762,12/10/2010,0:11 2889078,12/10/2010,15:45 2889079,12/10/2010,15:57 2889080,12/10/2010,15:57 2889081,12/10/2010,15:58 2889082,12/10/2010,16:10 2889083,12/10/2010,16:11 2889084,12/10/2010,16:11 2889085,12/10/2010,16:12 2889086,12/10/2010,16:12 2889087,12/10/2010,16:12 2889088,12/10/2010,16:13 2891529,12/14/2010,16:21

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  • Url Rewriting with Querystrings

    - by Alon
    In IIS 7.5, I'm trying to rewrite a Url such as /about to /content.asp?p=about, with support for QueryString-s, so if the orginal Url was /about?x=y, it should rewrite to /content.asp?p=about&x=y. The basic rewriting is now working, but when I'm trying to add a QueryString it doesn't work. Tried both /about?x=y and /about&x=y. My current rule: <rule name="RewriteUserFriendlyURL1" stopProcessing="false"> <match url="^([^/]+)/?$" /> <conditions> <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" /> <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" /> </conditions> <action type="Rewrite" url="content.asp?p={R:1}" /> </rule> How can I fix this? Thank you.

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  • Recursive CTE with alternating tables

    - by SOfanatic
    I've created a SQL fiddle here. Basically, I have 3 tables BaseTable, Files, and a LinkingTable. The Files table has 3 columns: PK, BaseTableId, RecursiveId (ChildId). What I want to do is find all the children given a BaseTableId (i.e., ParentId). The tricky part is that the way the children are found works like this: Take ParentId 1 and use that to look up a FileId in the Files table, then use that FileId to look for a ChildId in the LinkingTable, if that record exists then use the RecursiveId in the LinkingTable to look for the next FileId in the Files table and so on. This is my CTE so far: with CTE as ( select lt.FileId, lt.RecursiveId, 0 as [level], bt.BaseTableId from BaseTable bt join Files f on bt.BaseTableId = f.BaseTableId join LinkingTable lt on f.FileId = lt.FileId where bt.BaseTableId = @Id UNION ALL select rlt.FileId, rlt.RecursiveId, [level] + 1 as [level], CTE.BaseTableId from CTE --??? and this is where I get lost ... ) A correct output for BaseTableId = 1, should be: FileId|RecursiveId|level|BaseTableId 1 1 0 1 3 2 1 1 4 3 2 1

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  • how to combine the related version in group by

    - by randeepsp
    select count(a),b,c from APPLE join MANGO on (APPLE.link=MANGO.link) join ORANGE on (APPLE.link=ORANGE.link) where id='camel' group by b,c; the column b gives values like 1.0 1.0,R 1.0,B 2.0 2.0,B 2.0,R 3.0,C 3.0,R is there a way to modify the above quer so that all 1.0 and 1.0,R and 1.0,B are merged as 1.0 and 2.0,2.0,B are merged as 2.0 and same way for 3.0 and 4.0

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  • Does anybody have any suggestions on which of these two approaches is better for large delete?

    - by RPS
    Approach #1: DECLARE @count int SET @count = 2000 DECLARE @rowcount int SET @rowcount = @count WHILE @rowcount = @count BEGIN DELETE TOP (@count) FROM ProductOrderInfo WHERE ProductId = @product_id AND bCopied = 1 AND FileNameCRC = @localNameCrc SELECT @rowcount = @@ROWCOUNT WAITFOR DELAY '000:00:00.400' Approach #2: DECLARE @count int SET @count = 2000 DECLARE @rowcount int SET @rowcount = @count WHILE @rowcount = @count BEGIN DELETE FROM ProductOrderInfo WHERE ProductId = @product_id AND FileNameCRC IN ( SELECT TOP(@count) FileNameCRC FROM ProductOrderInfo WITH (NOLOCK) WHERE bCopied = 1 AND FileNameCRC = @localNameCrc ) SELECT @rowcount = @@ROWCOUNT WAITFOR DELAY '000:00:00.400' END

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  • Stored procs breaking overnight

    - by Chad
    We are running MS SQL 2005 and we have been experiencing a very peculiar problem the past few days. I have two procs, one that creates an hourly report of data. And another that calls it, puts its results in a temp table, and does some aggregations, and returns a summary. They work fine...until the next morning. The next morning, suddenly the calling report, complains about an invalid column name. The fix, is simply a recompile of the calling proc, and all works well again. How can this happen? It's happened three nights in a row since moving these procs into production.

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  • Best way to handle MySQL date for performance with thousands of users

    - by bitLost
    I am currently part of a team designing a site that will potentially have thousands of users who will be doing a number of date related searches. During the design phase we have been trying to determine which makes more sense for performance optimization. Should we store the datetime field as a mysql datetime. Or should be break it up into a number of fields (year, month, day, hour, minute, ...) The question is with a large data set and a potentially large set of users, would we gain performance wise breaking the datetime into multiple fields and saving on relying on mysql date functions? Or is mysql already optimized for this?

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  • How can I do this with MySQL partitions

    - by Uffo
    I have a table with millions of rows and I want to create some partions, but I really don't know how I can to this. I mean I want to have the data which is starting with the ID 1 - 10000 to be on partition one, and and the data that is starting with the ID 10001 - 20000 to be on partition two; and so on...?Can you give me an example how to do it? I have searched a lot on the internet and I read a lot of documentation, but I still don't understand how it needs to be done! Best Regards,

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