How to implement stored procedures in oracle to call stored procedures

1. What is a stored procedure?

A stored procedure is a special program created in the database. It is a collection of SQL statements, stored on the database server, and can be called by multiple applications. Stored procedures have the following characteristics:

1. Stored procedures are created in the database and are independent of the application, and their code is not affected by the application code.
2. Stored procedures can use control statements such as variables, conditional statements, and loop structures.
3. Stored procedures can accept parameters, which can be input parameters, output parameters, or both input and output parameters.
4. Stored procedures have high execution efficiency and high security, and can avoid security issues such as SQL injection.

2. Stored procedures call stored procedures

In Oracle database, the syntax for calling stored procedures is:

{call 存储过程名(参数)}

For example, we have the following two stored procedures :

1. Stored procedure A, used to query the basic information of employees based on employee IDs:

CREATE PROCEDURE A (IN_ID IN NUMBER, OUT_NAME OUT VARCHAR2, OUT_AGE OUT NUMBER) AS
BEGIN
  SELECT name, age INTO OUT_NAME, OUT_AGE FROM employees WHERE id = IN_ID;
END A;

2. Stored procedure B, used to query departments based on department IDs All employee information, the specific usage is to call stored procedure A to obtain the basic information of employees:

CREATE PROCEDURE B (IN_DEPARTMENT_ID IN NUMBER) AS
  CURSOR c_emp IS SELECT id FROM employees WHERE department_id = IN_DEPARTMENT_ID;
  v_emp_id employees.id%TYPE;
  v_emp_name employees.name%TYPE;
  v_emp_age employees.age%TYPE;
BEGIN
  FOR emp IN c_emp LOOP
    A(emp.id, v_emp_name, v_emp_age);
    DBMS_OUTPUT.PUT_LINE('员工ID：' || emp.id || '；员工姓名：' || v_emp_name || '；员工年龄：' || v_emp_age);
  END LOOP;
END B;

Stored procedure B obtains all employee IDs under the department through a cursor, and then calls stored procedure A to obtain the employee's name and age, and finally Print out the employee's basic information.

3. Summary

Stored procedure is a useful programming tool in Oracle database. It can implement more complex operations and can be called by multiple applications. When using stored procedures, you need to pay attention to the passing of parameters and the processing of return values. Especially when calling stored procedures, you need to handle them carefully to avoid deadlocks or other problems. During the development process, you should have an in-depth understanding of the relevant knowledge of stored procedures and flexibly use stored procedures to improve the performance and security of database applications.

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