colap Posted August 18, 2015 Share Posted August 18, 2015 What is the difference between IS NULL and =NULL? SELECT * FROM user,course WHERE user.course is NULL; SELECT * FROM user,course WHERE user.course=NULL; Tables information is here: http://www.sitepoint.com/understanding-sql-joins-mysql-database/ Quote Link to comment Share on other sites More sharing options...
requinix Posted August 18, 2015 Share Posted August 18, 2015 (edited) IS NULL is how you check whether a value is actually NULL or not. You will get true/1 or false/0. = NULL is normal comparison, except when you compare something with NULL you will simply get NULL as the result. Try it: SELECT 1 IS NULL; SELECT 0 IS NULL; SELECT NULL IS NULL; SELECT 1 = NULL; SELECT 0 = NULL; SELECT NULL = NULL; Edited August 18, 2015 by requinix Quote Link to comment Share on other sites More sharing options...
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