Adding DROP TRIGGER Statements in mysqldump Output

The mysqldump command in MySQL is used to create backups of databases. One of its options, --add-drop-trigger, adds DROP TRIGGER statements to the output file generated by mysqldump. This is particularly useful when you want to ensure that triggers are properly recreated when restoring the database from the dump file.

Here are several examples demonstrating the usage of --add-drop-trigger:

Example 1: Dump a database named mydatabase with DROP TRIGGER statements included:
mysqldump --add-drop-trigger mydatabase > mydatabase_dump.sql

Output: The file mydatabase_dump.sql will contain SQL statements to recreate the database mydatabase along with DROP TRIGGER statements for each trigger defined in the database.

Verification Steps: To verify, open the mydatabase_dump.sql file and search for occurrences of DROP TRIGGER statements. Each trigger should have a corresponding DROP TRIGGER statement before its CREATE TRIGGER statement.

Example 2: Dump all databases on the MySQL server with DROP TRIGGER statements:
mysqldump --add-drop-trigger --all-databases > alldatabases_dump.sql

Output: The file alldatabases_dump.sql will contain SQL statements for recreating all databases and their triggers, with each trigger preceded by a DROP TRIGGER statement.

Verification Steps: Similarly, check the generated dump file to ensure that DROP TRIGGER statements are present before each CREATE TRIGGER statement.

Example 3: Dump a specific table mytable from mydatabase with DROP TRIGGER statements:
mysqldump --add-drop-trigger mydatabase mytable > mytable_dump.sql

Output: The file mytable_dump.sql will contain SQL statements to recreate the table mytable along with any triggers associated with it, each with a preceding DROP TRIGGER statement.

Verification Steps: Examine mytable_dump.sql to confirm the presence of DROP TRIGGER statements before the corresponding CREATE TRIGGER statements for mytable.

Example 4: Dump a database, excluding table data but including DROP TRIGGER statements:
mysqldump --no-data --add-drop-trigger mydatabase > mydatabase_structure_dump.sql

Output: The file mydatabase_structure_dump.sql will contain SQL statements to recreate the structure of mydatabase (tables, triggers) without including any table data, with DROP TRIGGER statements for all triggers.

Verification Steps: Check the dump file to ensure that only the structure and triggers are included, with DROP TRIGGER statements correctly positioned.

Example 5: Dump a database and compress the output while including DROP TRIGGER statements:
mysqldump --add-drop-trigger mydatabase | gzip > mydatabase_dump.sql.gz

Output: This command will create a compressed file mydatabase_dump.sql.gz containing SQL statements for recreating mydatabase and its triggers, with DROP TRIGGER statements appropriately placed.

Verification Steps: Decompress the file using gzip -d mydatabase_dump.sql.gz and inspect the resulting mydatabase_dump.sql to verify the presence of DROP TRIGGER statements.

Read Also

Include DROP TABLE Statements in mysqldump Output
Add DROP DATABASE Statements in mysqldump Output
Omit Tablespace Information in mysqldump Output
Using Custom Configuration Files with mysqldump
Dump All Tablespaces with mysqldump