mysqldump: replace drop table in output with delete?
Specify to not use any creation SQL with --no-create-info

mysqldump mydatabase mytable --no-create-info --where="field=value"


If you want to overwrite the records on reload of the mysqldump, just add --replace

mysqldump mydatabase mytable --no-create-info --replace --where="field=value"


I suggested --replace because REPLACE is a mechanical DELETE and INSERT.

Give it a Try !!!