mysql stored procedure data

MySQL stored procedure data

MySQL is a popular relational database management system that supports the creation and use of stored procedures. A stored procedure is a piece of SQL code that can be stored and executed on the database server. Compared with ordinary SQL statements, stored procedures have better reusability and maintainability. In the actual development process, stored procedures can help program developers implement complex data operation logic and improve the performance and reliability of applications.

In MySQL, a stored procedure is an independent code block encapsulated in the database. It can be called by a name and has attributes such as input parameters, output parameters, and return values. In order to create and use stored procedures, we need to master MySQL stored procedure syntax and some common stored procedure cases.

MySQL stored procedure syntax

In MySQL, the syntax of stored procedures is very similar to that of general SQL statements. You only need to use specific keywords and statement blocks. The following is a simple stored procedure code:

DELIMITER $$ CREATE PROCEDURE HelloWorld() BEGIN SELECT 'Hello World'; END$$ DELIMITER ;

In the above code, we use theDELIMITERkeyword to set the end glyph ($$) that is different from the semicolon (;). Then create a stored procedure named HelloWorld through theCREATE PROCEDUREstatement,BEGINandENDmark the beginning and end of the code block,SELECT## The # statement is used to output data, and finally useDELIMITER ;to restore the end glyph to a semicolon. In this way, we can create a HelloWorld stored procedure in the MySQL database. The way to call the Hello World stored procedure is very simple. You only need to execute the following SQL statement:

CALL HelloWorld();

DELIMITER $$ CREATE PROCEDURE AddUsers(IN user_count INT) BEGIN DECLARE i INT DEFAULT 1; WHILE (i <= user_count) DO INSERT INTO users (username, password, email, created_at) VALUES (CONCAT('user_', i), 'password', CONCAT('user_', i, '@example.com'), NOW()); SET i = i + 1; END WHILE; END$$ DELIMITER ;

AddUsersstored procedure, which has a method nameduser_countAn input parameter that provides the number of users to add. Then we use theDECLAREstatement to define a variableifor iteratively adding users. In theWHILEloop statement block, we add users in batches through theINSERT INTOstatement. In each loop, we use theCONCATfunction to generate the username and email, theNOWfunction to generate the creation time, and insert this data into theuserstable. Finally, we use theSETstatement to update the value of the variablei, i increasing by 1 each time until the value ofuser_countis reached.

CALL AddUsers(10);

userstable with the username and email address ofuser_1@exampe.com ,user_2@example.com,...,user_10@example.com.

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