How to perform update in MySQL to disallow incrementing all the values above a specific value?


Let us first create a table −

mysql> create table DemoTable
   -> (
   -> Value int
   -> );
Query OK, 0 rows affected (0.54 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable values(100);
Query OK, 1 row affected (0.21 sec)

mysql> insert into DemoTable values(150);
Query OK, 1 row affected (0.13 sec)

mysql> insert into DemoTable values(180);
Query OK, 1 row affected (0.13 sec)

mysql> insert into DemoTable values(200);
Query OK, 1 row affected (0.14 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable;

Output

+-------+
| Value |
+-------+
|   100 |
|   150 |
|   180 |
|   200 |
+-------+
4 rows in set (0.00 sec)

Following is the query to UPDATE MySQL max value −

mysql> set @value:=45;
Query OK, 0 rows affected (0.00 sec)

mysql> update DemoTable
   -> set Value = LEAST(value + @value, 200) ;
Query OK, 3 rows affected (0.21 sec)
Rows matched: 4  Changed: 3 Warnings: 0

Let us check table records once again −

mysql> select *from DemoTable;

This will produce the following output. Here, we are disallowing incrementing a value to be above 200:

+-------+
| Value |
+-------+
|   145 |
|   195 |
|   200 |
|   200 |
+-------+
4 rows in set (0.00 sec)
raja
Published on 10-Jul-2019 15:37:39
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