What Cannot have a trigger associated with it MySQL table?

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 table?

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.

Why Cannot have a trigger associated with it MySQL?

A trigger can access both old and new data in its own table. A trigger can also affect other tables, but it is not permitted to modify a table that is already being used (for reading or writing) by the statement that invoked the function or trigger. (Before MySQL 5.0. 10, a trigger cannot modify other tables.)

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:
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Can a system table have trigger?

Having said that, it is technically possible to create trigger on system tables.

How do I run a trigger in PL SQL?

Syntax for creating trigger:

  1. CREATE [OR REPLACE ] TRIGGER trigger_name.
  2. {BEFORE | AFTER | INSTEAD OF }
  3. {INSERT [OR] | UPDATE [OR] | DELETE}
  4. [OF col_name]
  5. ON table_name.
  6. [REFERENCING OLD AS o NEW AS n]
  7. [FOR EACH ROW]
  8. WHEN (condition)

What are the types of triggers?

Types of Triggers

  • Data Manipulation Language (DML) Triggers. DML triggers are executed when a DML operation like INSERT, UPDATE OR DELETE is fired on a Table or View. …
  • Data Definition Language (DDL) Triggers. …
  • LOGON Triggers. …
  • CLR Triggers.

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.

Which statement is used to remove a trigger?

Which statement is used to remove a trigger? Explanation: In order to delete a trigger, the DROP TRIGGER statement is used. The DROP TRIGGER construct is used by writing the phrase ‘DROP TRIGGER’ followed by the scheme name specification.

How do I call a trigger in MySQL?

Use the BEGIN and END delimiters to indicate the trigger body: CREATE TRIGGER <trigger name> <trigger time > <trigger event> ON <table name> FOR EACH ROW BEGIN <trigger body>; END; Make sure to change the default delimiter before creating a trigger with multiple operations.

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What is trigger in database with example?

Trigger: A trigger is a stored procedure in database which automatically invokes whenever a special event in the database occurs. For example, a trigger can be invoked when a row is inserted into a specified table or when certain table columns are being updated.

What is MySQL interview questions?

Basic MySQL Interview Questions

  • What is MySQL? MySQL is a database management system for web servers. …
  • What are some of the advantages of using MySQL? …
  • What do you mean by ‘databases’? …
  • What does SQL in MySQL stand for? …
  • What does a MySQL database contain? …
  • How can you interact with MySQL? …
  • What are MySQL Database Queries?

CAN system table have trigger MySQL?

Triggers are stored in the mysql. triggers system table, which is part of the data dictionary.

How a database trigger is applied?

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.

What is the purpose of trigger?

Triggers are used to maintain the referential integrity of data by changing the data in a systematic fashion. Each trigger is attached to a single, specified table in the database. Triggers can be viewed as similar to stored procedures in that both consist of procedural logic that is stored at the database level.

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