Let’s talk about how to use MySQL stored procedures in PHP

Here we will introduce stored procedures in PHP and MySQL.

A stored procedure refers to a reusable SQL program, which is composed of SQL statements and control statements. Stored procedures can simplify large and complex queries, making them easier to use and maintain, and they can also improve the performance of large-scale applications. Both PHP and MySQL provide support for stored procedures, which can be run as part of an application or used as examples for development and research.

To use stored procedures, both PHP and MySQL provide corresponding functions and syntax. Below we will introduce the basic syntax of how to use MySQL stored procedures in PHP.

The basic syntax for creating a MySQL stored procedure is as follows:

CREATE PROCEDURE procedure_name
([IN/OUT] parameter_name data type [(size)]) 
BEGIN
--  SQL Statements
END;

Among them, "procedure_name" is the name of the stored procedure, "parameter_name" is the optional parameter name, which can be IN, OUT or INOUT type, "data type" is the parameter data type, and "size" is the parameter size. For example, we can create a stored procedure named "getcustomerinfo":

CREATE PROCEDURE getcustomerinfo (IN id INT)
BEGIN
SELECT * FROM customers WHERE customer_id = id;
END;

The basic syntax for using stored procedures in PHP is as follows:

$mysqli = new mysqli("localhost", "my_user", "my_password", "world");

// 调用存储过程
if ($stmt = $mysqli->prepare("CALL getcustomerinfo(?)")) {
    // 绑定参数
    $stmt->bind_param("i", $id);

    // 执行存储过程
    $stmt->execute();

    // 获取结果集
    $result = $stmt->get_result();

    // 处理结果集
    while ($row = $result->fetch_assoc()) {
        echo $row["customer_id"] . " " . $row["customer_name"] . "<br>";
    }

    // 释放结果集
    $result->free();

    // 关闭语句
    $stmt->close();
}

In the above example, we first call the stored procedure, The SQL statement is "CALL getcustomerinfo(?)". Then use the bind_param function to bind the parameters. This function accepts two parameters, the first is a string of parameter type, and the second is the parameter value. In this example, we are binding an integer value $id. Next, we execute the stored procedure and get the result set, using the fetch_assoc function to get each row of data from the result set. Finally, we release the result set and close the statement.

When using stored procedures, you should also pay attention to the following points:

1. The stored procedure must be created in the database, that is, created using the CREATE PROCEDURE statement.
2. When calling a stored procedure, you can use the prepare function and execute function, or you can use the query function to directly execute the stored procedure. Note that when using the query function, the keyword CALL must be used before the stored procedure name.
3. When calling a stored procedure, all input parameters need to be bound. You can use the bind_param function to bind.
4. The result returned by the stored procedure can be a result set, the number of affected rows, etc. When getting the result set, you should use the get_result function.
5. The execution of stored procedures can be surrounded by BEGIN and END statements. The statements between BEGIN and END will be executed as the body of the stored procedure.

To sum up, stored procedures are SQL programs that can make applications more efficient and easier to maintain. Both PHP and MySQL support the use of stored procedures. Proficient in the syntax and use of stored procedures can help with application development and maintenance.

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