mi_smallint mi_qual_column(MI_AM_QUAL_DESC *qualDesc);

qualDesc

points to the qualification descriptor.

A qualification identifies a column by a number that locates the column in the row descriptor. The mi_qual_column() function returns the number 0 for the first column specified in the row descriptor and adds 1 for each subsequent column.

For example, assume the WHERE clause contains the function equal(name,'harry') and that name is the second column in the row. The mi_qual_column() function returns the value 1.

The access method might need to identify the column by name, for example, to assemble a query for an external database manager. To retrieve the column name, pass the return value of mi_qual_column() and the row descriptor to the DataBlade API mi_column_name() function as in the following example:

rowDesc = mi_tab_rowdesc(tableDesc);
colnum=mi_qual_column(qualDesc);
colname=mi_column_name(rowDesc,colnum);

The integer identifies the column argument by its position in the table row.

See the descriptions of:

• Functions mi_qual_constant() and mi_tab_rowdesc()
• DataBlade API row-descriptor accessor functions in the IBM Informix: DataBlade API Programmer's Guide