SQL Server UNION OperatorIn SQL Server, the UNION operator is used to combine the result-set of two or more SELECT statements. Syntax: Parameter explanationexpression1, expression2, ... expression_n: expressions specify the columns or calculations that you want to compare between the two SELECT statements. tables: It specifies the tables that you want to retrieve records from. There must be at least one table listed in the FROM clause. WHERE conditions: It is optional condition. It specifies the conditions that must be met for the records to be selected. Image representation: Note: The covered blue area specifies the union data.UNION operator with single expressionExample: Output: UNION operator with multiple expressionsExample: Let's use multiple expressions of each table. For example: id, name, salary. Output: UNION ALL OperatorThe UNION operator selects only distinct values by default. So, the UNION ALL operator is used to allow duplicate values also. Example: Output:
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