How to use Oracle stored procedures and temporary tables

In Oracle database, a stored procedure is a piece of compiled executable code, similar to a function, which can be called multiple times for execution. Stored procedure is an important database object that facilitates complex operations and management of large amounts of data. The temporary table is a temporary table used in stored procedures to temporarily store data for subsequent queries or operations. This article will introduce the use and implementation of Oracle stored procedures and temporary tables.

1. Oracle stored procedures

In Oracle database, stored procedures are a set of precompiled SQL statements. They are composed in a certain order and can be called and executed multiple times. Stored procedures are similar to functions, but the difference is that stored procedures can have output parameters, and functions can only return a value. Usually, stored procedures are used to perform more complex operations and logic, such as data statistics, data analysis, etc.

1. Create a stored procedure

In Oracle database, you need to use the CREATE PROCEDURE statement to create a stored procedure. The specific syntax is as follows:

CREATE [OR REPLACE] PROCEDURE procedure_name
[(parameter1 [IN | OUT | IN OUT] type1, ...)]
IS
BEGIN

executable statements

[EXCEPTION

exception-handling statements]

END [procedure_name];

Among them, OR REPLACE is optional, which means that if a stored procedure with the same name already exists when creating a stored procedure, the original stored procedure will be replaced. The parameter parameter is optional and can contain zero or more stored procedure parameters, mainly including input parameters (IN), output parameters (OUT) and bidirectional parameters (IN OUT). The type parameter is required and is used to define the data type of the parameter.

2. Execute stored procedures

In Oracle, you need to use the EXECUTE statement to execute stored procedures, and its syntax is as follows:

EXECUTE procedure_name;

Among them, procedure_name is the name of the stored procedure that needs to be executed.

3. Delete stored procedures

If you no longer need a stored procedure, you can use the DROP PROCEDURE statement to delete it. The syntax is as follows:

DROP PROCEDURE procedure_name;

Among them, procedure_name is the name of the stored procedure to be deleted.

2. Oracle temporary table

In a stored procedure, a temporary table is a table used to temporarily store data. It is temporarily created when the stored procedure is executed and is automatically deleted after execution. Compared with ordinary tables in Oracle database, temporary tables have the following characteristics:

1. Temporary tables only exist during the execution of the stored procedure and are automatically deleted after execution.

2. Temporary tables can contain all types that ordinary tables can contain, and the data type of the temporary table is the same as the type used when it was created.

3. The storage location of temporary table data is in SGA (shared memory area), and the execution efficiency is high.

4. Creating a temporary table does not require reserving physical storage space in the database.

1. Create a temporary table

In Oracle database, you need to use the CREATE GLOBAL TEMPORARY TABLE statement to create a temporary table. The syntax of this statement is as follows:

CREATE GLOBAL TEMPORARY TABLE table_name
(column1 datatype [ NULL | NOT NULL ],
column2 datatype [ NULL | NOT NULL ],
...
) ON COMMIT { DELETE | PRESERVE } ROWS;

Among them, table_name is the name of the temporary table that needs to be created, and the column parameter is optional and is mainly used to define the columns of the table. The ON COMMIT parameter is used to define when the temporary table data will be deleted. DELETE means that the data of the temporary table will be cleared every time a transaction is submitted. PRESERVE means that the data of the temporary table will be cleared only at the end of the stored procedure.

2. Insert, update and delete data

In the stored procedure, you can perform data operations on temporary tables through INSERT, UPDATE and DELETE statements. The syntax is the same as that of ordinary tables. For example:

--Insert data
INSERT INTO temp_table (column1, column2, ...) VALUES (value1, value2, ...);

--Update data
UPDATE temp_table SET column1 = new_value1, column2 = new_value2 WHERE condition;

--Delete data
DELETE FROM temp_table WHERE condition;

3. Query temporary table data

To query the data of the temporary table, you need to use the SELECT statement inside the stored procedure. The syntax is the same as that of an ordinary table. For example:

SELECT * FROM temp_table WHERE column1 = value1;

4. Clearing of temporary tables

Clearing of temporary tables refers to deleting all data in the table, not Delete the table itself. The following two clearing methods are provided in Oracle database:

TRUNCATE TABLE: The

TRUNCATE TABLE statement is used to delete all data in the temporary table, but retains the structure and definition of the table. Its syntax is as follows ：

TRUNCATE TABLE table_name;

DROP TABLE：

The DROP TABLE statement is used to delete the structure and definition of the temporary table and its data. Its syntax is as follows:

DROP TABLE table_name;

Summary:

In Oracle database, stored procedures and temporary tables are very useful database objects, which facilitate complex operations and management of large amounts of data. A stored procedure is a set of precompiled SQL statements that are composed in a certain order and can be called and executed multiple times. A temporary table is a table used to temporarily store data. It is temporarily created when the stored procedure is executed. After the execution is completed, Automatically delete. By learning and mastering the use of stored procedures and temporary tables, you can manage and operate data in Oracle databases more effectively.

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