Record Matching Logic

The record matching joincondition may contain two parts: a STEPPED condition that may optionally be ANDed with non-STEPPED conditions. The STEPPED expression contains leading equality expressions of the fields from the SORTED option (trailing components may be range comparisons if the range values are independent of the LEFT and RIGHT rows), ANDed together, using LEFT and RIGHT as dataset qualifiers. If not present, the STEPPED condition is deduced from the fields specified by the SORTED option.

The order of the datasets within the setofdatasets can be significant to the way the joincondition is evaluated. The joincondition is duplicated between adjacent pairs of datasets, which means that this joincondition:

       LEFT.field = RIGHT.field

when applied against a setofdatasets containing three datasets, is logically equivalent to:

       ds1.field = ds2.field AND ds2.field = ds3.field