What Cannot have a trigger associated with it MySQL?
MySQL triggers cannot: Use SHOW , LOAD DATA , LOAD TABLE , BACKUP DATABASE, RESTORE , FLUSH and RETURN statements. Use statements that commit or rollback implicitly or explicitly such as COMMIT , ROLLBACK , START TRANSACTION , LOCK/UNLOCK TABLES , ALTER , CREATE , DROP , RENAME.
What Cannot have a trigger associated with it?
Since triggers execute as part of a transaction, the following statements are not allowed in a trigger: All create commands, including create database, create table, create index, create procedure, create default, create rule, create trigger, and create view. All drop commands. alter table and alter database.
What items can database triggers be associated with?
A triggering event can be one or more of the following:
- An INSERT , UPDATE , or DELETE statement on a specific table (or view, in some cases)
- A CREATE , ALTER , or DROP statement on any schema object.
- A database startup or instance shutdown.
- A specific error message or any error message.
- A user logon or logoff.
What are the triggers that can be used in MySQL tables?
There are 6 different types of triggers in MySQL:
- Before Update Trigger: As the name implies, it is a trigger which enacts before an update is invoked. …
- After Update Trigger: …
- Before Insert Trigger: …
- After Insert Trigger: …
- Before Delete Trigger: …
- After Delete Trigger:
What are some restrictions of triggers?
Restrictions for Triggers
- Triggers are not activated by foreign key actions.
- When using row-based replication, triggers on the replica are not activated by statements originating on the source. …
- The RETURN statement is not permitted in triggers, which cannot return a value.
Does MySQL use JSON?
MySQL supports a native JSON data type defined by RFC 7159 that enables efficient access to data in JSON (JavaScript Object Notation) documents. The JSON data type provides these advantages over storing JSON-format strings in a string column: Automatic validation of JSON documents stored in JSON columns.
What are the after triggers?
Explanation: The triggers run after an insert, update or delete on a table. They are not supported for views. … Explanation: AFTER TRIGGERS can be classified further into three types as: AFTER INSERT Trigger, AFTER UPDATE Trigger, AFTER DELETE Trigger.
How do you implement triggers?
Explanation of syntax:
- create trigger [trigger_name]: Creates or replaces an existing trigger with the trigger_name.
- [before | after]: This specifies when the trigger will be executed.
- {insert | update | delete}: This specifies the DML operation.
What is not an advantage of database views?
Although there are many advantages to views, the main disadvantage to using views rather than real tables is performance degradation. Because views only create the appearance of a table, not a real table, the query processor must translate queries against the view into queries against the underlying source tables.
What are 3 types of SQL triggers?
Types of SQL Triggers
These are – INSERT, UPDATE, and DELETE.
What are the two types of triggers?
There are two types of triggers.
- BEFORE trigger: – This trigger is called before the execution of the DML statement. …
- After Trigger: – this trigger is called after once DML statement is executed. …
- Combination of triggers: – We can have combination of row, statement, BEFORE and AFTER triggers.
What is the use of database triggers?
A database trigger is procedural code that is automatically executed in response to certain events on a particular table or view in a database. The trigger is mostly used for maintaining the integrity of the information on the database.