![]() I think your comment on mysql is a good one, although I personally wouldn't rely on poorly documented features if I could avoid it. Quite possibly for large queries that don't require sorting, the execute() call could return while at the back end the query is still matching rows. Without close inspection of the DBD::mysql source and possibly researching the MySQL API, I still wouldn't rely on this. Re^2: Count Number of rows retrieved from SELECT I'd be grateful if someone would take the time to explain the -'s. I know the documentation in DBI says that execute() is only guaranteed to return a true value on success, but a little poking around in DBD::mysql makes me think this is a real feature, if a poorly documented one. In this tutorial, you have learned how to use the SQLite MAX function to find the maximum value in a group of values.Update: I'm not sure why this keeps getting downvoted. HAVING MAX( bytes) > 6000000 Code language: SQL (Structured Query Language) ( sql ) You can combine the MAX function with the HAVING clause to filter the groups based on their largest values.įor example, to find the albums and their largest track where the sizes of the largest tracks are greater than 6 MB (about ~ 6000000), you use the following statement: SELECT Try It SQLite MAX function and HAVING clause Then, the MAX function returns the largest tracks for each group.ĪlbumId Code language: SQL (Structured Query Language) ( sql ) In SQLite Count () Function is an aggregate function that is used to return the total number of rows in a table based on the specified expression or conditions. Is there some library in C that allows me to easily check how many columns and rows there are in table 'test001' in 'testDB. You can find the largest track in each album using the MAX function with the GROUP BY clause.įirst, the GROUP BY clause groups the tracks into groups based on albums. 1 Currently, I have a database called 'testDB.db' that has 100 rows and 3 columns. SQLite MAX function and GROUP BY clause example Then, the outer query gets the largest track whose size equals the largest size returned by the subquery. WHERE Bytes = ( SELECT MAX( Bytes) FROM tracks) Code language: SQL (Structured Query Language) ( sql )įirst, the inner query returns highest bytes of all tracks using the MAX function. To get the complete information of the biggest track, you use the subquery as follows: SELECT Try It SQLite MAX function in the subquery example To get the largest track in bytes, you apply the MAX function to the bytes column as the following statement: SELECT MAX( bytes) FROM tracks Code language: SQL (Structured Query Language) ( sql ) We’ll use the tracks table in the sample database for the demonstration. ![]()
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