A bit of a warning, if the fields are DATETIME rather than DATE, add the appropriate hours:minutes:seconds to the test WHERE datetimefield >'1999-02-01 23:59:59'. When comparing DATETIME fields with date strings '00:00:00' is assumed and that can cause problems if one forgets that. > Have you considered NOT comparing dates as strings but rather as date > values? That will avoid the use of CONCAT() completely. > > > SELECT * > FROM sampletable > WHERE datefield >= '1999-01-12' and datefield <'1999-02-01' > > This example query will get all of the records from sampletable that > were entered after January 11th and before February 1st. It will also > be **very** fast if the column "datefield" is indexed. > > Shawn Green > Database Administrator > Unimin Corporation - Spruce Pine > > Alfredo Cole <[EMAIL PROTECTED]> wrote on 10/11/2004 09:43:14 AM: > >> Hi: >> >> I have a problem in that all statements that include concat execute >> very > >> slowly. For instance, if I have three fields in string format that > represent >> a year, month and day, and want to issue a select like: >> >> select * from cxcmanpag where contact >> (year,month,day)<=stringYear+stringMonth+stringDay (simplified), then >> it > will >> take a long time, againts a table with only around 100,00 records. If >> I rewrite the statement to read: >> >> select * from cxcmanpag where year<=stringYear and month<=stringMonth > and >> day<=stringDay, it will execute considerable faster, but will not > produce the >> same results. >> >> I have looked in the manual, and also read High Performance MySQL >> from Zawodny >> and Balling, and MySQL from Paul Dubois, but none of them seem to > address >> this issue. >> >> Can somebody point me to a URL or book that I should be reading to > improve, >> this, or how to avoid using concat altogether? >> >> Thank you. >> >> -- >> Alfredo J. Cole >> Grupo ACyC >> www.acyc.com - www.clshonduras.com - SolCom
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