SQLite Union All Operator To combine the result set of two or more tables without any elimination, the SQLite UNION All Operator is used with the SELECT statement. It is mandatory to have the same number of fields in the result set in each SELECT statement.
Syntax:
SELECT expression1, expression2, ... expression_n FROM tables WHERE conditions UNION ALL SELECT expression1, expression2, ... expression_n FROM tables WHERE conditions;
Example: STUDENTS Table:
| ID | NAME | SUBJECT |
| 1 | Tom | German |
| 2 | Jerry | Spanish |
| 3 | Bruno | English |
TEACHERS Table:
| ID | NAME | SALARY | SUBJECT |
| 1 | Jim | 10000 | Geology |
| 2 | John | 20000 | Geology |
| 3 | Watson | 15000 | Physics |
| 4 | Holmes | 25000 | Chemistry |
| 5 | Tony | 30000 | Physics |
SELECT SUBJECT FROM STUDENTS
UNION ALL
SELECT SUBJECT FROM TEACHERS; |
Output:
SUBJECT German Spanish English English Geology French Chemistry Physics
Explanation: In the above example, a union of the SUBJECT columns of the STUDENTS and the TEACHERS table is fetched without any elimination of the duplicate records.
