Let's talk about the definition of oracle out stored procedure

Oracle database is one of the most popular relational databases currently. It has powerful stored procedure functions, among which the out parameter is a commonly used one. In this article, we will discuss the definition, usage and usage scenarios of Oracle out stored procedures.

1. The concept of out parameters

The out parameter is a parameter type in the Oracle stored procedure. It can output the calculation results in the stored procedure or pass the value to the caller. Like other types of parameters, out parameters also need to be declared and assigned in the stored procedure definition.

2. Definition of out parameters

The definition of out parameters in Oracle stored procedures is similar to other types of parameters. Just add the out keyword before the parameter name. Here is a simple example:

CREATE OR REPLACE PROCEDURE PROC_OUT(

P_ID IN NUMBER,
P_NAME IN VARCHAR2,
P_AGE IN NUMBER,
P_SALARY OUT NUMBER

)
AS
BEGIN

SELECT SALARY INTO P_SALARY FROM EMPLOYEES WHERE ID = P_ID;

END;

In the above example, the definition of the stored procedure contains an out parameter P_SALARY. The value of this parameter needs to be assigned during the execution of the stored procedure and can be obtained by the calling function/procedure.

3. How to use out parameters

When using out parameters in a stored procedure, you need to pay attention to the following points:

1. When defining a stored procedure, you need to use out The keyword declares the parameter before the parameter name.
2. In the stored procedure body, you need to assign a value to this parameter.
3. The out parameter cannot be used for the return value of a stored procedure.

The following is an example of using the out parameter:

CREATE OR REPLACE PROCEDURE PROC_OUT(

P_ID IN NUMBER,
P_NAME IN VARCHAR2,
P_AGE IN NUMBER,
P_SALARY OUT NUMBER

)
AS
BEGIN

SELECT SALARY INTO P_SALARY FROM EMPLOYEES WHERE ID = P_ID;

END;

In this example, P_SALARY is an out parameter. The stored procedure will query the employee's salary from the EMPLOYEES table based on the entered employee ID, and assign the salary to the P_SALARY parameter.

4. Usage scenarios of out parameters

1. Insufficient return value of function

If more data needs to be returned, it exceeds the maximum value that the function can return value, or if there are multiple different return results, you can use the out parameter.

2. Output of database operation results

The out parameter is often used to output the results of data operations in stored procedures. For example, perform calculation on a certain table and output the result directly after calculation.

3. Data transfer between stored procedures

When data needs to be transferred between multiple stored procedures, you can use the out parameter to transfer it by outputting data.

In short, Oracle out stored procedures are very practical functions. During use, you need to pay attention to the definition, assignment and usage methods, as well as usage scenarios. Flexible, accurate and reasonable use of out parameters can make better use of the efficiency and functionality of stored procedures.

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