The syntax for updating a column with random number between 1-3 is is as follows −
update yourTableName set yourColumnName=FLOOR(1+RAND()*3);
To understand the above syntax, let us first create a table. The query to create a table is as follows −
mysql> create table UpdateNumber1To3 -> ( -> MyNumber int -> ); Query OK, 0 rows affected (0.61 sec)
Insert some records in the table using insert command. The query is as follows −
mysql> insert into UpdateNumber1To3 values(100); Query OK, 1 row affected (0.16 sec) mysql> insert into UpdateNumber1To3 values(140); Query OK, 1 row affected (0.25 sec) mysql> insert into UpdateNumber1To3 values(130); Query OK, 1 row affected (0.15 sec)
Display all records from the table using select statement. The query is as follows −
mysql> select *from UpdateNumber1To3;
The following is the output −
+----------+ | MyNumber | +----------+ | 100 | | 140 | | 130 | +--------+ 3 rows in set (0.00 sec)
Here is the query to update the MyNumber column values from 1 to 3 −
mysql> update UpdateNumber1To3 set Number=FLOOR(1+RAND()*3); Query OK, 3 rows affected (0.19 sec) Rows matched: 3 Changed: 3 Warnings: 0
Let us check the table once again. The query is as follows −
mysql> SELECT *FROM UpdateNumber1To3;
The following is the output with updated value −
+--------+ | Number | +--------+ | 1 | | 2 | | 1 | +--------+ 3 rows in set (0.00 sec)