Oracle MERGE語句
阿新 • • 發佈：2017-05-07
oracle merge
/* */>select * from emp_m;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ------------------------------ --------------------------- ---------- ------------------- ---------- ---------- ----------
7499 ALLEN SALESMAN 7698 1981-02-20 00:00:00 1600 310 30
7521 WARD SALESMAN 7698 1981-02-22 00:00:00 1250 510 30
7654 MARTIN SALESMAN 7698 1981-09-28 00:00:00 1250 1410 30
7844 TURNER SALESMAN 7698 1981-09-08 00:00:00 1500 10 30
7369 SMITH CLERK 7902 1980-12-17 00:00:00 800 20
7566 JONES MANAGER 7839 1981-04-02 00:00:00 2975 20
7698 BLAKE MANAGER 7839 1981-05-01 00:00:00 2850 30
7782 CLARK MANAGER 7839 1981-06-09 00:00:00 2450 10
7788 SCOTT ANALYST 7566 1987-04-19 00:00:00 3000 20
7839 KING PRESIDENT 1981-11-17 00:00:00 5000 10
7876 ADAMS CLERK 7788 1987-05-23 00:00:00 1100 20
7900 JAMES CLERK 7698 1981-12-03 00:00:00 950 30
7902 FORD ANALYST 7566 1981-12-03 00:00:00 3000 20
7934 MILLER CLERK 7782 1982-01-23 00:00:00 1300 10
14 rows selected.MERGE語句，它可以在一個SQL語句中對一張表或一個視圖同時做更新或插入操作，避免了多個INSERT、UPDATE和DELETE語句。它可以從一個或多個數據源中選擇數據對目標表做更新或插入操作，你可以指定在何種條件下更新或插入目標表或視圖。不可以對同一行做多次更新操作。例如：實現用B表來更新A表數據，如果A表中沒有，則把B表的數據插入A表。
11gR2語法如下：
MERGE [ hint ]
INTO [ schema. ] { table | view } [ t_alias ]
USING { [ schema. ] { table | view }
| subquery
} [ t_alias ]
ON ( condition )
[ merge_update_clause ]
[ merge_insert_clause ]
[ error_logging_clause ] ;
#merge_update_clause
WHEN MATCHED THEN
UPDATE SET column = { expr | DEFAULT }
[, column = { expr | DEFAULT } ]...
[ where_clause ]
[ DELETE where_clause ]
#merge_insert_clause
WHEN NOT MATCHED THEN
INSERT [ (column [, column ]...) ]
VALUES ({ expr | DEFAULT }
[, { expr | DEFAULT } ]...
)
[ where_clause ]
#error_logging_clause
LOG ERRORS
[ INTO [schema.] table ]
[ (simple_expression) ]
[ REJECT LIMIT { integer | UNLIMITED } ]使用例子說明MERGE語句的作用：
創建測試表emp_m
[email protected]>create table emp_m as select * from emp where comm is not null;
Table created.
[email protected]>select * from emp_m;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ------------------------------ --------------------------- ---------- ------------------- ---------- ---------- ----------
7499 ALLEN SALESMAN 7698 1981-02-20 00:00:00 1600 300 30
7521 WARD SALESMAN 7698 1981-02-22 00:00:00 1250 500 30
7654 MARTIN SALESMAN 7698 1981-09-28 00:00:00 1250 1400 30
7844 TURNER SALESMAN 7698 1981-09-08 00:00:00 1500 0 30例子1：插入和更新操作
現在測試表emp_m中只有comm不為空的數據，現在要把在emp表而不在emp_m表中的數據插入到emp_m表中，並把emp_m表中現有的數據的comm增加10。
[email protected]>MERGE INTO EMP_M M 2 USING EMP N 3 ON (M.EMPNO = N.EMPNO) 4 WHEN NOT MATCHED THEN 5 INSERT 6 (M.EMPNO, M.ENAME, M.JOB, M.MGR, M.HIREDATE, M.SAL, M.COMM, M.DEPTNO) 7 VALUES 8 (N.EMPNO, N.ENAME, N.JOB, N.MGR, N.HIREDATE, N.SAL, N.COMM, N.DEPTNO) 9 WHEN MATCHED THEN 10 UPDATE SET M.COMM = M.COMM + 10; 14 rows merged. [email protected]
例子2：實現刪除操作
從emp_m表中刪除表emp中DEPTNO=30的記錄。
[email protected]>MERGE INTO EMP_M M
2 USING (SELECT EMPNO FROM EMP WHERE DEPTNO = 30) N
3 ON (M.EMPNO = N.EMPNO)
4 WHEN MATCHED THEN
5 UPDATE SET M.COMM = DEFAULT
6 DELETE WHERE M.EMPNO = N.EMPNO;
6 rows merged.
[email protected]>select * from emp_m;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ------------------------------ --------------------------- ---------- ------------------- ---------- ---------- ----------
7369 SMITH CLERK 7902 1980-12-17 00:00:00 800 20
7566 JONES MANAGER 7839 1981-04-02 00:00:00 2975 20
7782 CLARK MANAGER 7839 1981-06-09 00:00:00 2450 10
7788 SCOTT ANALYST 7566 1987-04-19 00:00:00 3000 20
7839 KING PRESIDENT 1981-11-17 00:00:00 5000 10
7876 ADAMS CLERK 7788 1987-05-23 00:00:00 1100 20
7902 FORD ANALYST 7566 1981-12-03 00:00:00 3000 20
7934 MILLER CLERK 7782 1982-01-23 00:00:00 1300 10使用註意事項：
不能指定一個在它上面定義了INSTEAD OF觸發器的視圖為目標視圖。
USING子名指定源數據，可以是表、視圖或子查詢
UPDATE子句中的where條件可以指定目標表的條件也可以指定源表的條件
UPDATE子句中不能更新ON條件中的列，更新表時不能指定DEFAULT
UPDATE子句中指定DELETE WHERE用於刪除數據。
INSERT子句中，如果INSERT後省略列名，VALUES後的列的個數必須與目標表列個數一致
INSERT子句中，可以使用WHERE條件限制插入的數據
官方文檔：http://docs.oracle.com/cd/E11882_01/server.112/e41084/statements_9016.htm#SQLRF01606
本文出自 “DBA Fighting!” 博客，請務必保留此出處http://hbxztc.blog.51cto.com/1587495/1922868
Oracle MERGE語句