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)