criteria - Trying to use update query to only update fields that are blank in Microsoft Access -

criteria - Trying to use update query to only update fields that are blank in Microsoft Access -

i trying utilize update query update fields 1 table fields if fields in table updating blank. if contain information, not want overwrite existing data

e.g

field: name table: table 1 update to: [table2.][name] criteria:

i unsure of set in criteria. tried, 'is null', "".

here example:

update mytable set mytable.fieldb = "mynewvalue" (((mytable.fieldb) null));

ms-access criteria