[英]Alternatives for temporary tables in Oracle
How to do this in Oracle inside a stored procedure ? 如何在Oracle内部存储过程中执行此操作?
What is the business problem you are trying to solve? 您要解决的业务问题是什么? It is exceptionally rare that you need to use temporary tables in Oracle.
您需要在Oracle中使用临时表格,这种情况极为罕见。 Why wouldn't you simply
你为什么不这么简单
SELECT *
FROM employees
WHERE id = p_id_passed_in;
In other databases, you often create temporary tables because readers block writers so you want to create a separate copy of the data in order to avoid blocking any other sessions. 在其他数据库中,您经常创建临时表,因为读取器会阻止编写器,因此您希望创建单独的数据副本,以避免阻止任何其他会话。 In Oracle, however, readers never block writers, so there is generally no need to save off a separate copy of the data.
但是,在Oracle中,读者永远不会阻止编写者,因此通常无需保存单独的数据副本。
In other databases, you create temporary tables because you don't want to do dirty reads. 在其他数据库中,您可以创建临时表,因为您不想进行脏读。 Oracle, however, does not allow dirty reads.
但是,Oracle不允许脏读。 Multi-version read consistency means that Oracle will always show you the data as it existed when the query was started (or when the transaction started if you've set a transaction isolation level of serializable).
多版本读取一致性意味着Oracle将始终显示查询启动时存在的数据(或者如果您设置了可序列化的事务隔离级别,则事务启动时)。 So there is no need to create a temporary table to avoid dirty reads.
因此,无需创建临时表来避免脏读。
If you really wanted to use temporary tables in Oracle, you would not create the table dynamically. 如果您真的想在Oracle中使用临时表,则不会动态创建表。 You would create a global temporary table before you created the stored procedure.
您将在创建存储过程之前创建一个全局临时表。 The table structure would be visible to all sessions but the data would be visible only to the session that inserted it.
表结构对所有会话都是可见的,但数据只对插入它的会话可见。 You would populate the temporary table in the procedure and then query the table.
您将在过程中填充临时表,然后查询该表。 Something like
就像是
CREATE GLOBAL TEMPORARY TABLE temp_emp (
empno number,
ename varchar2(10),
job varchar2(9),
mgr number,
sal number(7,2)
)
ON COMMIT PRESERVE ROWS;
CREATE OR REPLACE PROCEDURE populate_temp_emp
AS
BEGIN
INSERT INTO temp_emp( empno,
ename,
job,
mgr,
sal )
SELECT empno,
ename,
job,
mgr,
sal
FROM emp;
END;
/
SQL> begin
2 populate_temp_emp;
3 end;
4 /
PL/SQL procedure successfully completed.
SQL> select *
2 from temp_emp;
EMPNO ENAME JOB MGR SAL
---------- ---------- --------- ---------- ----------
7623 PAV Dev
7369 smith CLERK 7902 800
7499 ALLEN SALESMAN 7698 1600
7521 WARD SALESMAN 7698 1250
7566 JONES MANAGER 7839 2975
7654 MARTIN SALESMAN 7698 1250
7698 BLAKE MANAGER 7839 2850
7782 CLARK MANAGER 7839 2450
7788 SCOTT ANALYST 7566 3000
7839 KING PRESIDENT 5000
7844 TURNER SALESMAN 7698 1500
7876 ADAMS CLERK 7788 1110
7900 SM0 CLERK 7698 950
7902 FORD ANALYST 7566 3000
7934 MILLER CLERK 7782 1300
1234 BAR
16 rows selected.
As I said, though, it would be very unusual in Oracle to actually want to use a temporary table. 正如我所说,在Oracle中实际想要使用临时表是非常不寻常的。
Create a global temporary table. 创建一个全局临时表。
CREATE GLOBAL TEMPORARY TABLE <your_table>
ON COMMIT PRESERVE ROWS # If needed. Depends on your needs.
AS SELECT <your_select_query>;
You can then select from the table as needed for the duration of your procedure. 然后,您可以根据需要在过程中选择表格。
http://www.oracle-base.com/articles/8i/TemporaryTables.php http://www.oracle-base.com/articles/8i/TemporaryTables.php
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:15826034070548 http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:15826034070548
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