Subqueries#
Subqueries (also known as inner queries or nested queries) are queries within
a query.
Subqueries can be used in SELECT, FROM, WHERE, and HAVING clauses.
The examples below are based on the following tables.
SELECT * FROM x;
+----------+----------+
| column_1 | column_2 |
+----------+----------+
| 1 | 2 |
+----------+----------+
| 2 | 4 |
+----------+----------+
SELECT * FROM y;
+--------+--------+
| number | string |
+--------+--------+
| 1 | one |
+--------+--------+
| 2 | two |
+--------+--------+
| 3 | three |
+--------+--------+
| 4 | four |
+--------+--------+