Oracle批量、大量Update方法總結

一、業務場景：

  （1）主從兩個表，主表Student，有字段id、name、sex，從表Boy，有字段id、name，主從表同一對象id相同

  （2）從表Boy的name屬性被業務修改，定時批量處理主表，以維持主表name屬性與從表一致 

二、表結構

1、主表 Student

2、從表 Boy

三、建表SQL（DDL）

  1、主表 Student

-- DDL
CREATE TABLE student (
id NUMBER NOT NULL ,
name VARCHAR2(255 BYTE) NULL ,
sex VARCHAR2(255 BYTE) NULL
)
 
ALTER TABLE student ADD CHECK (id IS NOT NULL);
 
-- DML
INSERT INTO student VALUES ('1', 'zhangsan', 'boy');
INSERT INTO student VALUES ('2', 'lisi', 'girl');
INSERT INTO student VALUES ('3', 'wangwu', 'boy');

 2、從表 Boy

-- DDL
CREATE TABLE boy (
id NUMBER NOT NULL ,
name VARCHAR2(255 BYTE) NULL
)
 
-- DML
INSERT INTO boy VALUES ('1', '張三');
INSERT INTO boy VALUES ('3', '王五');

四、DML

  1、基本語法

-- DML
UPDATE student s SET s.name = '張三' WHERE   id = 1; 

  2、變相

 -- DML，0.015s
UPDATE student s
SET s.name = (
  SELECT b.name FROM boy b WHERE s.id = b.id AND s.name != b.name
)
WHERE EXISTS (
  SELECT 1 FROM boy b WHERE s.id = b.id AND s.name != b.name
);
 

3、快速游標法

 -- DML，0.014s
BEGIN
  FOR cur IN (
    SELECT s.id sid, b.name bname
  FROM student s, boy b
  WHERE s.id = b.id AND s.name != b.name AND s.sex = 'boy'
  ) loop 
 
  UPDATE student s SET s.name = cur.bname WHERE s.id = cur.sid;
  
  END loop ;
END ;
 

4、內聯視圖法（inline View）

 -- DML，0.019s
UPDATE (
  SELECT
    s.name sname, b.name bname
 FROM
    student s, boy b
 WHERE
    s.id = b.id AND s.name != b.name
)
SET sname = bname;
 

  報錯提示：ORA-01779: 無法修改與非鍵值保存表對應的列

    參考資料，從表id必須增加主鍵約束，且為視圖內的where條件：

 -- DDL
ALTER TABLE boy ADD CONSTRAINT pk_id PRIMARY KEY (id);  

  5、合並法（Merge）

MERGE INTO student s USING boy b ON (
 s.id = b.id AND s.sex = 'boy' AND s.name != b.name
)
WHEN MATCHED THEN
 UPDATE SET s.name = b.name;  

報錯提示：ORA-38104: 無法更新 ON 子句中引用的列

    參考資料，錯誤原因是條件重復，正確寫法：

 -- DML，0.016s
MERGE INTO student s USING boy b ON (
 s.id = b.id AND s.sex = 'boy'
--   AND s.name != b.name
)
WHEN MATCHED THEN
 UPDATE SET s.name = b.name;  

6、子查詢關聯

update service cs set (cs.customer_id,cs.customer_code,cs.customer_name)=  
 (
     select ccb.customer_id,ccb.customer_code,ccb.customer_name from customer_base ccb 
     inner join customer_contact ccc
     on ccb.customer_id=ccc.customer_id 
     where ccc.key_='1' and ccc.value_=cs.value_ and rownum<2
 )
 where customer_id='0' and start_time>sysdate-30