Re[2]: [PHP-DB] Re: SQL WHERE datetime > NOW

Hello John, Tuesday, January 6, 2004, 6:00:09 PM, you wrote: J> http://www.mysql.com/doc/en/LIMIT_optimisation.html J> If you use LIMIT row_count with ORDER BY, MySQL will end the sorting as soon J> as it has found the first row_count lines instead of sorting the whole J> table. I wish it did. Rarely in practise do I ever see this happen. I wonder if it's version specific? Real world example from a 191,404 row table: explain select messageid from message order by messageid limit 0,50 From the profile: table,type,possible_keys,key,key_len,ref,rows,Extra message,index,NULL,PRIMARY,4,NULL,191404,Using index So it's definitely doing something with 191,404 rows. It's sorting the entire table based on the index and bringing back the 50 rows I asked for. Which does make sense I guess (even if it does seem to contradict the MySQL manual) J> I meant to largest 10 values in a column. For example, I have a record with J> ID number 1800 in an auto increment field, table has 1805 records. When I J> view the table 'raw' record 1800 appears after record 12. I wanted records J> 1755-1805. Instead now I've retrieved the whole table with ORDER BY without J> LIMIT and put my start and end values in the for () loop. Now, my eyes may J> have deceived me... Use ORDER BY and LIMIT together? Unless you are doing this already, not sure. Assuming your auto increment field is called "id": SELECT * FROM table ORDER BY id DESC LIMIT 0,50 -- Best regards, Richard mailto:rich@launchcode.co.uk