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Can a trigger call a stored procedure MySQL?
MySQL allows you to call a stored procedure from a trigger by using the CALL statement. By doing this, you can reuse the same stored procedure in several triggers. However, the trigger cannot call a stored procedure that has OUT or INOUT parameters or a stored procedure that uses dynamic SQL.
How do I create a stored function in MySQL?
The syntax to create a function in MySQL is: CREATE FUNCTION function_name [ (parameter datatype [, parameter datatype]) ] RETURNS return_datatype BEGIN declaration_section executable_section END; function_name. The name to assign to this function in MySQL.
Which MySQL statement can be used with triggers?
The trigger can be executed when you run one of the following MySQL statements on the table: INSERT, UPDATE and DELETE and it can be invoked before or after the event.
How can we use signal statement with MySQL triggers?
For catch-all error handling, we should assign an SQLSTATE value of ‘45000’, which signifies an “unhandled user-defined exception.” To illustrate the use of SIGNAL statement with MySQL triggers we are using the following example in which we are creating a BEFORE INSERT trigger on the student_age table.
Why does MySQL call a stored procedure from a trigger database?
Such would be the case if triggers were manipulating tables with INSERTs and UPDATEs being stagnated to perform heavy duty MVCC inside each call to a trigger. Don’t forget that Triggers require overhead. In fact, According to MySQL Stored Procedure Programming, page 256 under the head “Trigger Overhead” says the following:
How does MySQL trigger or launch an external script?
One feature I often wish MySQL / MariaDB (I’ll refer from now to just MariaDB referring to both) had was the ability to trigger or launch an external script or open a socket connection to some external site; on a database event. Perhaps using a stored procedure in other words generate a signal /event to an outside application directly.
What is the keyword for the SIGNAL statement?
Here, the SIGNAL keyword is an SQLSTATE value or a condition name declared by a DECLARE CONDITION statement. The SIGNAL statement must always specify an SQLSTATE value or a named condition that defined with an SQLSTATE value. The SQLSTATE value for a The SIGNAL statement consists of a five-character alphanumeric code.