MySQL Overview (10) triggers

1 trigger can monitor additions and deletions, and trigger additions and deletions to change the operation.

For some logically related operations, you do not have to manually operate multiple times.

2. Elements:

3. Syntax:

Add: MySQL can set the Terminator, do not have to be ";" to end the flag, you can use

3.1 Simple examples:

3.2 Trigger statement references new data

View triggers: show triggers;

: How to feel that this trigger is too rough, if only the update is some non-attention to the data, will also cause triggering, resulting in unnecessary operations.

4.after/before differences

Tables involved:

MySQL Overview (10) triggers