Frequent question: What Cannot have a trigger associated with it MySQL?

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 can have a trigger associated with it MySQL?

A trigger in MySQL is a set of SQL statements that reside in a system catalog. It is a special type of stored procedure that is invoked automatically in response to an event. Each trigger is associated with a table, which is activated on any DML statement such as INSERT, UPDATE, or DELETE.

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.

Which statement Cannot be used in stored routines MySQL?

Stored routines cannot contain arbitrary SQL statements. The following statements are not permitted: The locking statements LOCK TABLES and UNLOCK TABLES . ALTER VIEW .

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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.

Which 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 the different triggers?

What are the types of triggers?

  • DDL Trigger.
  • DML Trigger.
  • Logon Trigger.

How do I edit a trigger in MySQL?

To modify a DML trigger

Expand the database that you want, expand Tables, and then expand the table that contains the trigger that you want to modify. Expand Triggers, right-click the trigger to modify, and then click Modify. Modify the trigger, and then click Execute.

What is trigger and its advantages?

Advantages of Triggers

Enforces referential integrity. Event logging and storing information on table access. Auditing. Synchronous replication of tables. Imposing security authorizations.

How do you write a trigger?

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. on [table_name]: This specifies the name of the table associated with the trigger.

Which of the following Cannot be used in a SQL statement?

Which of the following is not a type of SQL statement? Explanation: Data Communication Language (DCL) is not a type of SQL statement. Explanation: The CREATE TABLE statement is used to create a table in a database.Tables are organized into rows and columns; and each table must have a name.

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Which statement can not be used inside stored routines?

Stored routines cannot use LOAD DATA INFILE . Statements that return a result set cannot be used within a stored function. This includes SELECT statements that do not use INTO to fetch column values into variables, SHOW statements, and other statements such as EXPLAIN .

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