DATA ITEM DISPLAY METHOD AND DEVICE, AND RECORDING MEDIUM STORING A PROGRAM FOR CONTROLLING DISPLAY OF DATA ITEM

In order to make sure that a user does not attempt to build an invalid database query in which tables are incorrectly joined on fields that cannot be joined due to an incompatibility of data types, after the user selects a source data field the incompatible target data fields which cannot be joined with the selected source data field are determined automatically and displayed distinctly differently in a target list box of possible target data field names, such as in a different color.