You can take advantage of default values of stored procedure parameters with either of two forms of the CALL statement.
If the optional parameters are at the end of the argument list in the CREATE PROCEDURE statement, they may be omitted from the CALL statement. As an example, consider a procedure with three INOUT parameters:
CREATE PROCEDURE SampleProcedure( INOUT var1 INT DEFAULT 1, INOUT var2 int DEFAULT 2, INOUT var3 int DEFAULT 3 ) ...
This example assumes that the calling environment has set up three variables to hold the values passed to the procedure:
CREATE VARIABLE V1 INT; CREATE VARIABLE V2 INT; CREATE VARIABLE V3 INT;
The procedure SampleProcedure may be called supplying only the first parameter as follows:
CALL SampleProcedure( V1 );
in which case the default values are used for var2 and var3.
A more flexible method of calling procedures with optional arguments is to pass the parameters by name. The SampleProcedure procedure may be called as follows:
CALL SampleProcedure( var1 = V1, var3 = V3 );
or as follows:
CALL SampleProcedure( var3 = V3, var1 = V1 );