>Thank you Borislav. I will use your approach. I have just changed the last part like this...
>
>

>lcSql   = lcSql + [ FROM TempTable]+;
>                  [ LEFT JOIN MasterTable ON ]+lcJoin+;
>                  [ INTO CURSOR crsTest]
>

>
>...because I just want to know what is new in TempTable.

All will look like this then:

lcSql  = [SELECT ]
lcJoin = []
FOR lnFor = 1 TO FCOUNT([MasteTable])
    lcFld   = FIELD(lnFor,[MasteTable])
    lcSql   = lcSql   + IIF(lnFor = 1, [],[,])     + [TempTable.] + lcFld
    lcJoin  = lcJoin  + IIF(lnFor = 1, [],[ AND ]) + [TempTable.] + lcFld + [ == MasterTable.]+lcFld
NEXT
lcSql   = lcSql + [ FROM TempTable ]+;
                  [LEFT JOIN MasterTable ON ]+lcJoin+;
                  [ WHERE MatserTable.KeyFld IS NULL]+;
                  [ INTO CURSOR crsTest]
...