gustavbrock / vba.djoin

Domain aggregate function to join (concat) related field values

VBA.DJoin

Join (concat) values from one field from a table or query

As you can union records, you can join field values. DJoin offers increased speed and flexibility compared to the ancient ConcatRelated and similar functions. Further, it offers better read-out of Multi-Value fields.

For decades, functions have been around to solve the simple task of joining (concatenating) the values from a single field of many records to a single field value - as illustrated by the title picture, where the values from two keys (left) are joined into one field for each key (right) with a delimiter (or separator), here a space.

DJoin is named such to signal the familiarity with the native domain aggregate functions - DLookup, DCount, etc. - as it aggregates the values from one field from many records to one string - much like Join does for an array.

Areas for improvement and added flexibility:

• Better speed, indeed when browsing
• A wider choice of source types - like pure SQL
• Caching of results for vastly improved speed for repeated calls

The function SpeedTest (from the attached demo below) reveals - for a large table of ~170,000 records having 424 keys - a speed improvement on the first run of about 25%. Repeated calls run about 16 times faster - a dramatic speed increase:

Code

Code has been tested with both 32-bit and 64-bit Microsoft Access 2016 and 365.

Documentation

Full documentation can be found here:

Join (concat) values from one field from a table or query

Included is a Microsoft Access example application.

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