MySQL UNION SELECT and IN clause in a single query

Let us first create a table −

mysql> create table DemoTable1
   -> (
   -> StudentId int,
   -> StudentName varchar(20)
   -> );
Query OK, 0 rows affected (1.24 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable1 values(210,'Adam');
Query OK, 1 row affected (0.11 sec)

Display all records from the table using select statement −

mysql> select * from DemoTable1;

This will produce the following output −

+-----------+-------------+
| StudentId | StudentName |
+-----------+-------------+
|       210 | Adam        |
+-----------+-------------+
1 row in set (0.00 sec)

Here is the query to create second table −

mysql> create table DemoTable2
   -> (
   -> StudentId int,
   -> StudentName varchar(20)
   -> );
Query OK, 0 rows affected (0.69 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable2 values(100,'Chris');
Query OK, 1 row affected (0.30 sec)

Display all records from the table using select statement −

mysql>  select * from DemoTable2;

This will produce the following output −

+-----------+-------------+
| StudentId | StudentName |
+-----------+-------------+
|       100 | Chris       |
+-----------+-------------+
1 row in set (0.00 sec)

Here is the query for MySQL UNION SELECT and IN clause −

mysql> select StudentName from
   -> (
   -> select StudentId,StudentName from DemoTable1
   -> UNION
   -> select StudentId,StudentName from DemoTable2
   -> ) tbl
   -> where StudentId IN(210,100);

This will produce the following output −

+-------------+
| StudentName |
+-------------+
| Adam        |
| Chris       |
+-------------+
2 rows in set (0.00 sec)