将两个不同的查询作为一个mysql查询执行

SELECT column1, column2, ... FROM table1
UNION
SELECT column1, column2, ... FROM table2;

table1:
+----+-------+
| ID | Name  |
+----+-------+
| 1  | John  |
| 2  | Alice |
+----+-------+

table2:
+----+-------+
| ID | Name  |
+----+-------+
| 3  | Bob   |
| 4  | Alice |
+----+-------+

SELECT ID, Name FROM table1
UNION
SELECT ID, Name FROM table2;

+----+-------+
| ID | Name  |
+----+-------+
| 1  | John  |
| 2  | Alice |
| 3  | Bob   |
+----+-------+

SELECT column1, column2 FROM table1;
SELECT column3, column4 FROM table2;

SELECT column1, column2, (SELECT column3 FROM table2) AS column3, (SELECT column4 FROM table2) AS column4 FROM table1;