UNION Statement

Combine data from one or more SELECT statements.

In Oracle 8i and above the UNION command has been supplemented by the new Analytic Features

Syntax:

SELECT command  {UNION | UNION ALL | INTERSECT | MINUS} SELECT command

key:

UNION - Combine the unique rows returned by 2 SELECT statements

UNION ALL - Combine the rows returned by 2 SELECT statements (including all duplicates)

INTERSECT - Return only those rows that are in *both* SELECT statements

MINUS - Return the rows that are in the first SELECT but not the second

To combine more than two SELECTs nest the expressions:

SELECT expr1 UNION (SELECT expr2 UNION SELECT expr3)

Related Oracle Commands:

SELECT - Retrieve data from one or more tables, views, or snapshots.

Related Views:

  DBA_ALL_TABLES       ALL_ALL_TABLES       USER_ALL_TABLES
  DBA_TABLES           ALL_TABLES           USER_TABLES         TAB
  DBA_VIEWS            ALL_VIEWS            USER_VIEWS 
                                                                DICTIONARY
                                                                DICT_COLUMNS


 
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