oracle stored procedure execute sql

Oracle is currently the most widely used database management system across industries. Oracle stored procedures are a very important function in Oracle. It can help database administrators and developers simplify complex data operations and query processes so that they can be processed more efficiently. Manage and use databases. In this article, we will explore how Oracle stored procedures execute SQL and how to use SQL statements in stored procedures.

1. What is Oracle stored procedure?

Oracle stored procedures are pre-compiled blocks of code that can be stored and reused in the Oracle database. It is a collection of SQL statements and control structures, suitable for complex data operations and query processes. Oracle stored procedures can be executed independently or called from other applications.

The main purpose of Oracle stored procedures is to simplify database operations for database administrators and developers, thereby improving database performance and security. Stored procedures can reduce network traffic and the burden on the database server because one request can replace multiple SQL statements. In addition, stored procedures can also provide a unified data access interface for multiple users, thereby improving data consistency and reliability.

2. How does Oracle stored procedure execute SQL?

Oracle stored procedures can execute any valid SQL statement, including SELECT, INSERT, UPDATE, DELETE, etc. Stored procedures usually contain two types of statements: DDL (data definition language) and DML (data manipulation language).

1. DDL statement

DDL statement is used to create, modify or delete database objects, such as tables, views, indexes, etc. When using DDL statements in stored procedures, you need to pay attention to the following points:

(1) DDL statements need to be executed using the EXECUTE IMMEDIATE statement.

(2) DDL statements do not allow the use of bind variables, so the variables in the statement must be replaced with actual values.

(3) DDL statements may affect the execution of transactions, so they must be used with care.

The following is an example of a stored procedure that uses DDL statements to create a table:

CREATE OR REPLACE PROCEDURE CREATE_TABLE AS
BEGIN
EXECUTE IMMEDIATE 'CREATE TABLE employee (

                  emp_id   NUMBER(10)   NOT NULL,
                  first_name VARCHAR2(50),
                  last_name  VARCHAR2(50),
                  PRIMARY KEY (emp_id))';

END;

This stored procedure will create a table named employee to record employee information.

2. DML statement

DML statements are used to manipulate data in the database, such as INSERT, UPDATE, DELETE, etc. When using DML statements in stored procedures, you need to pay attention to the following points:

(1) DML statements need to be executed using the EXECUTE IMMEDIATE statement.

(2) DML statements can use bind variables to avoid SQL injection attacks.

(3) DML statements must use COMMIT or ROLLBACK statements to commit or rollback transactions to ensure data consistency property.

The following is an example of a stored procedure that uses DML statements to insert data into a table:

CREATE OR REPLACE PROCEDURE INSERT_EMPLOYEE (p_id NUMBER, p_first_name VARCHAR2, p_last_name VARCHAR2) AS
BEGIN
EXECUTE IMMEDIATE 'INSERT INTO employee (emp_id, first_name, last_name) VALUES (:1, :2, :3)'

USING p_id, p_first_name, p_last_name;

COMMIT;
END;

The The stored procedure will insert the values ​​​​in the three parameters into the employee table.

3. How to use SQL statements in the stored procedure?

In the stored procedure, you can use SQL statements to query, Insert, update or delete data. Usually, stored procedures dynamically generate SQL statements based on the parameters passed in to perform different queries and operations.

The following is an example of a stored procedure that uses a SQL SELECT statement to query data ：

CREATE OR REPLACE PROCEDURE GET_EMPLOYEE (p_id NUMBER) AS
v_first_name VARCHAR2(50);
v_last_name VARCHAR2(50);
BEGIN
SELECT first_name, last_name INTO v_first_name, v_last_name
FROM employee
WHERE emp_id = p_id;

DBMS_OUTPUT.PUT_LINE('First Name: ' || v_first_name || ' Last Name: ' || v_last_name);
END;

This stored procedure will query the employee table based on the passed ID parameter and output the results to standard output. Other types of operations and queries can be implemented using corresponding SQL statements.

IV. Summary

Oracle stored procedure is a very practical function in Oracle database. It can simplify complex data operations and query processes to a great extent, improve database performance and safety. In stored procedures, you can use SQL statements to perform various data operations and queries, including DDL statements and DML statements. When using stored procedures, you need to pay attention to how SQL statements are used and how transactions are processed to ensure data consistency and security.

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