It depends on the distribution of the 4 'values' in that field. If the cardinality is poor, then INDEX(VAL) won't be used, and they will all do a table scan.
> -----Original Message----- > From: Anupam Karmarkar [mailto:sb_akarmar...@yahoo.com] > Sent: Friday, November 16, 2012 12:36 AM > To: mysql@lists.mysql.com > Subject: Query Optimization > > Hi All, > > Consider a scenario, I have table XYZ which contains value follow BLUE RED > GREEN NULL > > following are queries we can use get this values > > 1. SELECT * FROM XYX WHERE VAL IN ('BLUE','RED','GREEN'); 2. SELECT * FROM > XYZ WHERE VAL IS NOT NULL 3. SELECT * FROM XYZ WHERE VAL = 'BLUE' OR > VAL='RED' OR VAL='GREEN' > and more > > So which one is good in terms of optimization. I guess, 1 and 3 are similar > in term of formation. > > > --Anupam -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql
