oracle stored procedure return value

Oracle is a widely used database system, and stored procedures are an efficient way to process data. It can separate data processing logic and business logic, effectively improving the performance and security of the database system. When using Oracle stored procedures, we may need to return some data or values. The return values ​​of Oracle stored procedures will be discussed below.

1. Return value types of stored procedures

Oracle stored procedures support multiple return value types, such as integers, characters, dates, etc. The specific return value type needs to be determined based on specific business requirements. The following takes querying an employee's monthly salary as an example to illustrate how to use Oracle stored procedures to return a numeric type of data.

CREATE OR REPLACE PROCEDURE EMP_SALARY
(
in_emp_id IN NUMBER,
out_salary OUT NUMBER
)
IS
BEGIN
SELECT salary INTO out_salary FROM employee WHERE employee_id = in_emp_id;
END EMP_SALARY;

The above stored procedure inputs an employee number through in_emp_id, and then returns the employee's monthly salary through out_salary. The stored procedure declares two parameters, in_emp_id is the input parameter and out_salary is the output parameter. The SELECT statement is used in the stored procedure to query the results, and the query results are assigned to the output parameter out_salary.

2. Error handling of stored procedures

When developing stored procedures, possible errors should be taken into consideration, such as empty input parameters or empty query results. In stored procedures, these errors can be handled well using the EXCEPTION statement or the RAISE_APPLICATION_ERROR procedure.

CREATE OR REPLACE PROCEDURE EMP_SALARY
(
in_emp_id IN NUMBER,
out_salary OUT NUMBER
)
IS
emp_salary NUMBER(18,2);
BEGIN
SELECT salary INTO emp_salary FROM employee WHERE employee_id = in_emp_id;
IF emp_salary IS NULL THEN

RAISE_APPLICATION_ERROR(-20000, 'The employee salary is null.');

END IF;
out_salary := emp_salary;
EXCEPTION
WHEN OTHERS THEN

RAISE_APPLICATION_ERROR(-20001, 'The employee salary could not be retrieved.');

END EMP_SALARY;

The above stored procedure adds a statement to determine whether emp_salary is empty when querying. If emp_salary is empty, a custom error message will be thrown. If other errors occur, a default error message will be thrown. In the development of stored procedures, using a good error handling mechanism can improve the robustness and reliability of the program.

3. Result sets returned by stored procedures

In Oracle stored procedures, in addition to returning individual data types, a result set can also be returned. Stored procedures can return results in a data set, which can simplify code implementation when multiple result sets need to be used. The following will take a piece of code as an example to demonstrate how to use Oracle stored procedures to return a result set:

CREATE OR REPLACE PROCEDURE query_blogs
(
out_blogs OUT SYS_REFCURSOR
) AS
BEGIN
OPEN out_blogs FOR SELECT * FROM blog;
END query_blogs;

In this code, the SYS_REFCURSOR type is used as the output parameter type, which can be used to return data set results. Use the OPEN statement in the stored procedure to open the result set, and use the SELECT query statement to obtain the result set that needs to be returned.

Stored procedures are an important part of the Oracle database. When developing stored procedures, you need to consider not only the functional implementation of the stored procedure, but also reasonable return values ​​and error handling. At the same time, using stored procedures can effectively improve the performance and security of the database system, reduce duplication of work when writing the same program code, and improve the overall efficiency of the application.

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