The mi_qual_param_constisnull() accessor function
The mi_qual_param_constisnull() function determines whether the arguments to a qualification function include a NULL constant.
Syntax
mi_boolean mi_qual_param_constisnull(MI_AM_PARAM_DESC *paramDesc);- paramDesc
- Points to the parameter descriptor.
Usage
The mi_qual_param_constisnull() function returns MI_TRUE for functions that have the following format: function(column, NULL). The mi_qual_param_constisnull() function returns MI_FALSE for functions that contain a constant other than NULL, for example, function(column, 10).
The form function(column,?) cannot occur because the parameter descriptor that the database server passes to the am_beginscan or am_getnext purpose function contains values for any host-variable argument.
Do not call this function from the am_scancost purpose function. Use mi_qual_constisnull_nohostvar() function instead.
Return values
- MI_TRUE
- Indicates that the arguments include an explicit NULL-valued constant.
- MI_FALSE
- Indicates that the arguments do not include an explicit NULL-valued constant.