Microsoft SQL Server’s INTERSECT
“returns any distinct values that are returned by both the query on the left and right sides of the INTERSECT operand” This is different from a standard INNER JOIN
or WHERE EXISTS
query.
SQL Server
CREATE TABLE table_a (
id INT PRIMARY KEY,
value VARCHAR(255)
);
CREATE TABLE table_b (
id INT PRIMARY KEY,
value VARCHAR(255)
);
INSERT INTO table_a VALUES (1, 'A'), (2, 'B'), (3, 'B');
INSERT INTO table_b VALUES (1, 'B');
SELECT value FROM table_a
INTERSECT
SELECT value FROM table_b
value
-----
B
(1 rows affected)
MySQL
CREATE TABLE `table_a` (
`id` INT NOT NULL AUTO_INCREMENT,
`value` varchar(255),
PRIMARY KEY (`id`)
) ENGINE=InnoDB;
CREATE TABLE `table_b` LIKE `table_a`;
INSERT INTO table_a VALUES (1, 'A'), (2, 'B'), (3, 'B');
INSERT INTO table_b VALUES (1, 'B');
SELECT value FROM table_a
INNER JOIN table_b
USING (value);
+-------+
| value |
+-------+
| B |
| B |
+-------+
2 rows in set (0.00 sec)
SELECT value FROM table_a
WHERE (value) IN
(SELECT value FROM table_b);
+-------+
| value |
+-------+
| B |
| B |
+-------+
With this particular question, the id column is involved, so duplicate values will not be returned, but for the sake of completeness, here’s a MySQL alternative using INNER JOIN
and DISTINCT
:
SELECT DISTINCT value FROM table_a
INNER JOIN table_b
USING (value);
+-------+
| value |
+-------+
| B |
+-------+
And another example using WHERE ... IN
and DISTINCT
:
SELECT DISTINCT value FROM table_a
WHERE (value) IN
(SELECT value FROM table_b);
+-------+
| value |
+-------+
| B |
+-------+