Home Database Mysql Tutorial Oracle 子程序参数模式,IN,OUT,NOCOPY

Oracle 子程序参数模式,IN,OUT,NOCOPY

Jun 07, 2016 pm 06:06 PM
oracle

Oracle 子程序参数模式主要有IN,OUT,NOCOPY,IN和OUT可以组合,OUT和NOCOPY也可以组合使用.

IN主要用于传入参数,可以是变量,常量,表达式,在子程序内部不能改变其值.
代码如下:
DECLARE
n NUMBER := 10;
PROCEDURE do_something (
n1 IN NUMBER) IS
BEGIN
dbms_output.put_line(n1); -- prints 10
--n1:=20; --illegal assignment.
END;
BEGIN
do_something(n);
do_something(20);
END;

OUT模式用于返回值,必须传入变量调用,变量的初始的值不会传给形式参数,如>所示.
形参的值在子程序返回时(不是在形式参数改变时)才copy给实参, ,如>所示,如果在 返回之前发生异常,实际参数的值不会被改变.
代码如下:
DECLARE
n NUMBER := 10;
PROCEDURE do_something (
n1 OUT NUMBER) IS
BEGIN
dbms_output.put_line('before assign: ' || n1); -- prints none >
n1:=20;
dbms_output.put_line('before return: ' || n); -- prints 10 >
END;
BEGIN
do_something(n);
dbms_output.put_line('after return: ' || n); -- prints 20
END;

NOCOPY模式用于限定OUT模式在调用时是不是以传引用的方式进行(它只是一个编译器暗示,不一定总是起作用),默认情况下,OUT模式的参数是以传值的方式进行调用的.
IN主要用于传入参数的,虽然n2 := 20被调用,但是要到返回的时候才生效.如>所示.
NOCOPY是传引用,会在赋值的时候立即生效 ,如>所示,如果在 返回之前发生异常,实际参数的值也会被改变.
由于OUT参数在 子程序返回的时候会将值copy到实际参数,所以调用完后n的值为20,如>所示.
代码如下:
DECLARE
n NUMBER := 10;
PROCEDURE do_something (
n1 IN NUMBER,
n2 IN OUT NUMBER,
n3 IN OUT NOCOPY NUMBER) IS
BEGIN
n2 := 20;
dbms_output.put_line(n1); -- prints 10>
n3 := 30;
dbms_output.put_line(n1); -- prints 30 >
END;
BEGIN
do_something(n, n, n);
dbms_output.put_line(n); -- prints 20 >
END;

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

How to encrypt oracle view How to encrypt oracle view Apr 11, 2025 pm 08:30 PM

Oracle View Encryption allows you to encrypt data in the view, thereby enhancing the security of sensitive information. The steps include: 1) creating the master encryption key (MEk); 2) creating an encrypted view, specifying the view and MEk to be encrypted; 3) authorizing users to access the encrypted view. How encrypted views work: When a user querys for an encrypted view, Oracle uses MEk to decrypt data, ensuring that only authorized users can access readable data.

How to uninstall Oracle installation failed How to uninstall Oracle installation failed Apr 11, 2025 pm 08:24 PM

Uninstall method for Oracle installation failure: Close Oracle service, delete Oracle program files and registry keys, uninstall Oracle environment variables, and restart the computer. If the uninstall fails, you can uninstall manually using the Oracle Universal Uninstall Tool.

How to delete all data from oracle How to delete all data from oracle Apr 11, 2025 pm 08:36 PM

Deleting all data in Oracle requires the following steps: 1. Establish a connection; 2. Disable foreign key constraints; 3. Delete table data; 4. Submit transactions; 5. Enable foreign key constraints (optional). Be sure to back up the database before execution to prevent data loss.

How to check invalid numbers of oracle How to check invalid numbers of oracle Apr 11, 2025 pm 08:27 PM

Oracle Invalid numeric errors may be caused by data type mismatch, numeric overflow, data conversion errors, or data corruption. Troubleshooting steps include checking data types, detecting digital overflows, checking data conversions, checking data corruption, and exploring other possible solutions such as configuring the NLS_NUMERIC_CHARACTERS parameter and enabling data verification logging.

What to do if the oracle can't be opened What to do if the oracle can't be opened Apr 11, 2025 pm 10:06 PM

Solutions to Oracle cannot be opened include: 1. Start the database service; 2. Start the listener; 3. Check port conflicts; 4. Set environment variables correctly; 5. Make sure the firewall or antivirus software does not block the connection; 6. Check whether the server is closed; 7. Use RMAN to recover corrupt files; 8. Check whether the TNS service name is correct; 9. Check network connection; 10. Reinstall Oracle software.

How to paginate oracle database How to paginate oracle database Apr 11, 2025 pm 08:42 PM

Oracle database paging uses ROWNUM pseudo-columns or FETCH statements to implement: ROWNUM pseudo-columns are used to filter results by row numbers and are suitable for complex queries. The FETCH statement is used to get the specified number of first rows and is suitable for simple queries.

How to solve the problem of closing oracle cursor How to solve the problem of closing oracle cursor Apr 11, 2025 pm 10:18 PM

The method to solve the Oracle cursor closure problem includes: explicitly closing the cursor using the CLOSE statement. Declare the cursor in the FOR UPDATE clause so that it automatically closes after the scope is ended. Declare the cursor in the USING clause so that it automatically closes when the associated PL/SQL variable is closed. Use exception handling to ensure that the cursor is closed in any exception situation. Use the connection pool to automatically close the cursor. Disable automatic submission and delay cursor closing.

How to create cursors in oracle loop How to create cursors in oracle loop Apr 12, 2025 am 06:18 AM

In Oracle, the FOR LOOP loop can create cursors dynamically. The steps are: 1. Define the cursor type; 2. Create the loop; 3. Create the cursor dynamically; 4. Execute the cursor; 5. Close the cursor. Example: A cursor can be created cycle-by-circuit to display the names and salaries of the top 10 employees.

See all articles