A mutating table error (ORA-04091) occurs when a row-level trigger tries to examine or change a table that is already undergoing change (via an INSERT, UPDATE, or DELETE statement). In particular, this error occurs when a row-level trigger attempts to read or write the table from which the trigger was fired.Accordingly, what is a mutating table?
A mutating table is a table that is currently being modified by an UPDATE, DELETE, or INSERT statement, or it is a table that might need to be updated by the effects of a declarative DELETE CASCADE referential integrity constraint.
Similarly, what is the mutating table and constraining table? Answer: A table which is currently being modified by a DML statement like defining triggers in a table is known as a Mutating table. A table that might need to be read from for a referential integrity constraint is known as constraining table.
Likewise, what is mutating error how do you avoid it?
Avoiding Mutating triggers The Oracle mutating trigger error occurs when a trigger references the table that owns the trigger, resulting in the "ORA-04091: table name is mutating, trigger/function may not see it." message. Don't use triggers - The best way to avoid the mutating table error is not to use triggers.
What are the different types of triggers?
Types of Triggers. In SQL Server we can create four types of triggers Data Definition Language (DDL) triggers, Data Manipulation Language (DML) triggers, CLR triggers, and Logon triggers.
Can we commit inside a trigger?
Yes, you can commit inside the trigger. But for this you have to make this trigger transaction to be an Independent transaction from its parent transaction, you can do this by using Pragma. Pragma AUTONOMOUS_TRANSACTION allow you to build the Independent (child) Transaction, started by another.What is a mutating table error and how can you get around it?
A mutating table error (ORA-04091) occurs when a row-level trigger tries to examine or change a table that is already undergoing change (via an INSERT, UPDATE, or DELETE statement). In particular, this error occurs when a row-level trigger attempts to read or write the table from which the trigger was fired.What is Pragma Autonomous_transaction?
The AUTONOMOUS_TRANSACTION pragma changes the way a subprogram works within a transaction. A subprogram marked with this pragma can do SQL operations and commit or roll back those operations, without committing or rolling back the data in the main transaction. Pragmas are processed at compile time, not at run time.What are Oracle triggers?
A trigger is a named PL/SQL block stored in the Oracle Database and executed automatically when a triggering event takes place. The event can be any of the following: A data manipulation language (DML) statement executed against a table e.g., INSERT , UPDATE , or DELETE .What is the maximum number of triggers in a table?
2, you can have only six triggers on a table: one trigger for each combination of time (BEFORE, AFTER) and action (INSERT, UPDATE, DELETE). As of MySQL 5.7. 2 or later, you can have multiple triggers for each time and action.How do you check if a trigger is fired?
To test if a trigger fires you can add a PRINT statement to the trigger (e.g. "PRINT 'trigger fired!' "), then do something that should trigger the trigger. If you get the printed text in your messages-tab in management studio you know it fired.What is trigger in SQL?
In a DBMS, a trigger is a SQL procedure that initiates an action (i.e., fires an action) when an event (INSERT, DELETE or UPDATE) occurs. A trigger cannot be called or executed; the DBMS automatically fires the trigger as a result of a data modification to the associated table.What is instead of trigger in Oracle?
An INSTEAD OF trigger is a trigger that allows you to update data in tables via their view which cannot be modified directly through DML statements. When you issue a DML statement such as INSERT , UPDATE , or DELETE to a non-updatable view, Oracle will issue an error.What is Pragma in PL SQL?
In Oracle PL/SQL, PRAGMA refers to a compiler directive or "hint" it is used to provide an instruction to the compiler. The directive restricts member subprograms to query or modify database tables and packaged variables. PRAGMA EXCEPTION_INIT: This directive binds a user defined exception to a particular error number.What is ref cursor in Oracle?
Introduction to REF CURSORs Using REF CURSOR s is one of the most powerful, flexible, and scalable ways to return query results from an Oracle Database to a client application. A REF CURSOR is a PL/SQL data type whose value is the memory address of a query work area on the database.Can we use Pragma Autonomous_transaction in trigger?
FUNCTION balance (acct_id INTEGER) RETURN REAL IS PRAGMA AUTONOMOUS_TRANSACTION; my_bal REAL; BEGIN END; END banking; In the example below, you mark a database trigger as autonomous. Unlike regular triggers, autonomous triggers can contain transaction control statements.What is compound trigger?
A compound trigger is a single trigger on a table that enables you to specify actions for each of four timing points: Before the firing statement. Before each row that the firing statement affects. After each row that the firing statement affects.What is bulk collect in Oracle?
A bulk collect is a method of fetching data where the PL/SQL engine tells the SQL engine to collect many rows at once and place them in a collection. The SQL engine retrieves all the rows and loads them into the collection and switches back to the PL/SQL engine. All the rows are retrieved with only 2 context switches.What is statement level trigger?
A statement-level trigger is fired whenever a trigger event occurs on a table regardless of how many rows are affected. In other words, a statement-level trigger executes once for each transaction. For example, if you update 1000 rows in a table, then a statement-level trigger on that table would only be executed once.Why packages are used in Oracle?
Packages let you encapsulate logically related types, items, and subprograms in a named PL/SQL module. Each package is easy to understand, and the interfaces between packages are simple, clear, and well defined. This aids application development.How do I disable a trigger?
Disable a single trigger If don't want to the ALTER TRIGGER command, you can use SQL Developer tool to disable a trigger using these steps: First, right-click the trigger name and select Disable… menu item. Second, click the Apply button in the dialog to disable the trigger.What is the difference between record and collection in Oracle?
In a collection, the internal components always have the same data type, and are called elements. To create a collection variable, you either define a collection type and then create a variable of that type or use %TYPE . In a record, the internal components can have different data types, and are called fields. 
