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Set custom messages by working with MySQL IF Statements and SELECT in a user-defined variable
Let us first create a table −
mysql> create table DemoTable2008 ( Value int ); Query OK, 0 rows affected (10.59 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable2008 values(10); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable2008 values(20); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable2008 values(30); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable2008 values(-31); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable2008 values(-28); Query OK, 1 row affected (0.17 sec)
Display all records from the table using select statement −
mysql> select * from DemoTable2008;
This will produce the following output −
+-------+ | Value | +-------+ | 10 | | 20 | | 30 | | -31 | | -28 | +-------+ 5 rows in set (0.00 sec)
Here is the query to first work with a user-defined variable and taking input as a SELECT −
mysql> set @value:=(select sum(Value) from DemoTable2008); Query OK, 0 rows affected (0.03 sec) mysql> select if(@value > 0, 'Value is greater than 0','Not greater than') as Result;
This will produce the following output −
+-------------------------+ | Result | +-------------------------+ | Value is greater than 0 | +-------------------------+ 1 row in set (0.00 sec)
Updated on: 02-Jan-2020
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