docs/UserGuide/UDF/Triggers.md

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# Triggers



## Triggers Management

You can register, deregister, start or stop a trigger instance through SQL statements, and you can also query all registered triggers through SQL statements.

Triggers have two states: `STARTED` and `STOPPED`. You can start or stop a trigger by executing `START TRIGGER` or `STOP TRIGGER`. Note that the triggers registered by the `CREATE TRIGGER` statement are `STARTED` by default.



### Create Triggers

The following shows the SQL syntax of how to register a trigger.

```sql
CREATE TRIGGER <TRIGGER-NAME>
(BEFORE | AFTER) INSERT
ON <FULL-PATH>
AS <CLASSNAME>
```

You can also set any number of key-value pair attributes for the trigger through the `WITH` clause:

```sql
CREATE TRIGGER <TRIGGER-NAME>
(BEFORE | AFTER) INSERT
ON <FULL-PATH>
AS <CLASSNAME>
WITH (
  <KEY-1>=<VALUE-1>, 
  <KEY-2>=<VALUE-2>, 
  ...
)
```

Note that `CLASSNAME`, `KEY` and `VALUE` in key-value pair attributes need to be quoted in single or double quotes.



### Drop Triggers

The following shows the SQL syntax of how to deregister a trigger.

```sql
DROP TRIGGER <TRIGGER-NAME>
```



### Start Triggers

The following shows the SQL syntax of how to start a trigger.

```sql
START TRIGGER <TRIGGER-NAME>
```



### Stop Triggers

The following shows the SQL syntax of how to stop a trigger.

```sql
STOP TRIGGER <TRIGGER-NAME>
```



### Show All Registered Triggers

``` sql
SHOW TRIGGERS
```