How can I append comma except lastline?

With following shell script, * I read file * and for each line * generates SQL fragments

#!/bin/bash
CURRDATE=$(date +'%Y-%m-%d %H:%M:%S')
echo $CURRDATE
echo $OUTPUT

echo "SET SESSION AUTOCOMMIT = 0;" > $OUTPUT
echo 'START TRANSACTION;' >> $OUTPUT

echo $'INSERT INTO ...' >> $OUTPUT
echo 'VALUES' >> $OUTPUT
cat $INPUT | tr -d '\r' | while IFS= read -r LINE; do
echo $"(..., '$LINE', ...)," >> $OUTPUT
done

echo "COMMIT;" >> $OUTPUT

The output look like this,

SET SESSION AUTOCOMMIT = 0;
START TRANSACTION;
SET @created_at = '2024-08-09 09:30:45';
INSERT INTO ...
VALUES
(...),
(...),
(...), -- <<<<<<<<<<<<<<<< should be a semi-colon
COMMIT;

How can suppress the last comma? So that I put semi-colon?