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The Difference Between

What is the difference between labor union and professional bodies?

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March 28, 2008 7:38PM

The UNION statement in SQL is used to join to result sets that have the same number and type of columns. The UNION statement by default will eliminate duplicate rows (where all columns are the same). If you know that you will not have this condition, or it is not desired to get a DISTINCT recordset back, then use the UNION ALL statement (this will help with performance also).