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SQL UNION operator Description The SQL UNION operator is used to combine the result sets of 2 or more SELECT statements. It removes duplicate rows between the various SELECT statements. Each SELECT statement within the UNION must have the same number of fields in the result sets with similar data types.  Syntax The syntax for the SQL UNION operator is: SELECT expression1, expression2, ... expression_n FROM tables WHERE conditions UNION SELECT expression1, expression2, ... expression_n FROM tables WHERE conditions; Parameters or Arguments expression1 , expression2 , expression_n are the columns or calculations that you wish to retrieve. tables are the tables that you wish to retrieve records from. There must be at least one table listed in the FROM clause. conditions are conditions that must be met for the records to be selected. Note There must be same number of expressions in both SELECT statements. See also the UNION ALL operator. Example - Return single field The following ...

SQL UNION ALL operator Description The SQL UNION ALL operator is used to combine the result sets of 2 or more SELECT statements. It returns all rows from the query (even if the row exists in more than one of the SELECT statements). Each SELECT statement within the UNION ALL must have the same number of fields in the result sets with similar data types.  Syntax The syntax for the SQL UNION ALL operator is: SELECT expression1, expression2, ... expression_n FROM tables WHERE conditions UNION ALL SELECT expression1, expression2, ... expression_n FROM tables WHERE conditions; Parameters or Arguments expression1 , expression2 , expression_n are the columns or calculations that you wish to retrieve. tables are the tables that you wish to retrieve records from. There must be at least one table listed in the FROM clause. conditions are conditions that must be met for the records to be selected. Note There must be same number of expressions in both SELECT statements. See also the UNION ...