GROUP BY and display only non-empty column values in MySQL

Let us first create a table −

mysql> create table DemoTable
   -> (
   -> Id varchar(100),
   -> Message varchar(200)
   -> );
Query OK, 0 rows affected (1.17 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable values('1','');
Query OK, 1 row affected (0.23 sec)

mysql> insert into DemoTable values('1','Hi');
Query OK, 1 row affected (0.21 sec)

mysql> insert into DemoTable values('2','Hello');
Query OK, 1 row affected (0.15 sec)

mysql> insert into DemoTable values('3','Awesome');
Query OK, 1 row affected (0.18 sec)

mysql> insert into DemoTable values('3','Good Morning');
Query OK, 1 row affected (0.11 sec)

mysql> insert into DemoTable values('2',NULL);
Query OK, 1 row affected (0.15 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable;

Output

+------+--------------+
| Id   | Message      |
+------+--------------+
| 1    |              |
| 1    | Hi           |
| 2    | Hello        |
| 3    | Awesome      |
| 3    | Good Morning |
| 2    | NULL         |
+------+--------------+
6 rows in set (0.00 sec)

Following is the query to group by and select first non-empty columns −

mysql> select Id,min(Message) from DemoTable
   -> where Message IS NOT NULL and  length(Message) > 0
   -> group by Id;

Output

+------+--------------+
| Id   | min(Message) |
+------+--------------+
| 1    | Hi           |
| 2    | Hello        |
| 3    | Awesome      |
+------+--------------+
3 rows in set (0.06 sec)

Rama Giri

Published on 10-Jul-2019 15:30:08