GROUP BY a column in another MySQL table

For this, you can use CREATE TABLE AS SELECT statement. Let us first create a table −

mysql> create table DemoTable1
   -> (
   -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   -> CountryName varchar(20)
   -> );
Query OK, 0 rows affected (0.68 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable1(CountryName) values('US');
Query OK, 1 row affected (0.15 sec)

mysql> insert into DemoTable1(CountryName) values('UK');
Query OK, 1 row affected (0.27 sec)

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

mysql> insert into DemoTable1(CountryName) values('UK');
Query OK, 1 row affected (0.13 sec)

mysql> insert into DemoTable1(CountryName) values('UK');
Query OK, 1 row affected (0.06 sec)

mysql> insert into DemoTable1(CountryName) values('US');
Query OK, 1 row affected (0.10 sec)

mysql> insert into DemoTable1(CountryName) values('AUS');
Query OK, 1 row affected (0.10 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable1;

Output

+----+-------------+
| Id | CountryName |
+----+-------------+
| 1  | US          |
| 2  | UK          |
| 3  | AUS         |
| 4  | UK          |
| 5  | UK          |
| 6  | US          |
| 7  | AUS         |
+----+-------------+
7 rows in set (0.00 sec)

Following is the query to GROUP BY a column in another table −

mysql> create table DemoTable2 AS select *from DemoTable group by CountryName;
Query OK, 3 rows affected (0.79 sec)
Records: 3 Duplicates: 0 Warnings: 0

Now check the records in the new table −

mysql> select *from DemoTable2;

Output

+----+-------------+
| Id | CountryName |
+----+-------------+
| 1  | US          |
| 2  | UK          |
| 3  | AUS         |
+----+-------------+
3 rows in set (0.00 sec)