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What do you mean MySQL user variables and how can we assign values to
them?
MySQL user variables are written as @variable and it may be set to an integer, real, string or NULL value. With the help of SET statement, we can assign a value to the user variable. We can use either = or := as the assignment operator while assigning the values to user variables.
Example
mysql> SET @A = 100; Query OK, 0 rows affected (0.00 sec) mysql> Set @B = 'MySQL'; Query OK, 0 rows affected (0.00 sec)
The above queries have assigned the values 100 to user variable A and ‘MySQL’ to user variable B respectively.
We can check for their values with the help of SELECT statements as follows −
mysql> Select @A, @B; +------+-------+ | @A | @B | +------+-------+ | 100 | MySQL | +------+-------+ 1 row in set (0.05 sec)
We can also perform multiple variable assignments, separated by commas. It is illustrated in the following example −
mysql> SET @X = 'Ram',@Y = 'Shyam',@Z = 'Students', @S = 5000; Query OK, 0 rows affected (0.00 sec) mysql> Select @X, @Y, @Z, @S; +------+-------+----------+------+ | @X | @Y | @Z | @S | +------+-------+----------+------+ | Ram | Shyam | Students | 5000 | +------+-------+----------+------+ 1 row in set (0.00 sec)
We can also assign values to them with SELECT statement but for that, we must have to use only := assignment operator and not =. It is illustrated in the example below −
mysql> SELECT @C := 'Tutorialspoint'; +------------------------+ | @C := 'Tutorialspoint' | +------------------------+ | Tutorialspoint | +------------------------+ 1 row in set (0.00 sec) mysql> SELECT @C; +----------------+ | @C | +----------------+ | Tutorialspoint | +----------------+ 1 row in set (0.00 sec)
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