Returns 1 if a user-defined variable has been created or declared with a given name. Returns 0 if no such variable has been created.
VAREXISTS( variable-name-string )
variable-name-string The variable name to be tested, as a string.
SQL/2003 Vendor extension.
The following IF statement creates a variable with a name start_time if one is not already created or declared. The variable can then be used safely.
IF VAREXISTS( 'start_time' ) = 0 THEN CREATE VARIABLE start_time TIMESTAMP; END IF; SET start_time = current timestamp;