Αποτελέσματα Αναζήτησης
The UNION operator is a set operator that combines result sets of two or more SELECT statements into a single result set. The following illustrates the syntax of the UNION operator that combines the result sets of two queries: SELECT column_list_1 FROM T1 UNION SELECT column_list_1 FROM T2; Code language: SQL (Structured Query Language) (sql)
The UNION operator is used to combine the result-set of two or more SELECT statements. Every SELECT statement within UNION must have the same number of columns. The columns must also have similar data types. The columns in every SELECT statement must also be in the same order. UNION Syntax. SELECT column_name (s) FROM table1. UNION.
UNION combines the result from multiple SELECT statements into a single result set. Example: mysql> SELECT 1, 2; . +---+---+. | 1 | 2 |. +---+---+. | 1 | 2 |. +---+---+. mysql> SELECT 'a', 'b'; . +---+---+. | a | b |. +---+---+. | a | b |. +---+---+. mysql> SELECT 1, 2 UNION SELECT 'a', 'b'; . +---+---+. | 1 | 2 |. +---+---+. | 1 | 2 |.
UNION combines the result from multiple query blocks into a single result set. This example uses SELECT statements: mysql> SELECT 1, 2; +---+---+. | 1 | 2 |. +---+---+. | 1 | 2 |. +---+---+. mysql> SELECT 'a', 'b'; +---+---+. | a | b |. +---+---+. | a | b |. +---+---+. mysql> SELECT 1, 2 UNION SELECT 'a', 'b'; +---+---+. | 1 | 2 |. +---+---+.
UNION combines the result from multiple query blocks into a single result set. This example uses SELECT statements: mysql> SELECT 1, 2; +---+---+. | 1 | 2 |. +---+---+. | 1 | 2 |. +---+---+. mysql> SELECT 'a', 'b'; +---+---+. | a | b |. +---+---+. | a | b |. +---+---+. mysql> SELECT 1, 2 UNION SELECT 'a', 'b'; +---+---+. | 1 | 2 |. +---+---+.
You can combine multiple queries using the set operators UNION, UNION ALL, INTERSECT, and MINUS. All set operators have equal precedence. If a SQL statement contains multiple set operators, then Oracle Database evaluates them from the left to right unless parentheses explicitly specify another order.
table1 . UNION [ALL] SELECT . column3, column4. FROM . table2; Code language: SQL (Structured Query Language) (sql) To use the UNION operator, you write the dividual SELECT statements and join them by the keyword UNION. The columns returned by the SELECT statements must have the same or convertible data type, size, and be the same order.
