Obtain NULL values
The mi_value() and mi_value_by_name() functions return the MI_NULL_VALUE value status for a column that contains the SQL NULL value. These functions return MI_NULL_VALUE for columns of any data type.
When the mi_value() or mi_value_by_name() function
returns MI_NULL_VALUE, the contents of the MI_DATUM structure
that these functions pass back depends on whether the control mode
for the query data is text or binary representation, as the following
table shows.
| Control mode | Contents of value buffer (From mi_value() or mi_value_by_name()) |
|---|---|
| Text representation | No valid value |
| Binary representation | The internal representation of the SQL NULL value for the data type |