Oracle批量、大量Update方法总结

一、业务场景：

  （1）主从两个表，主表Student，有字段id、name、sex，从表Boy，有字段id、name，主从表同一对象id相同

  （2）从表Boy的name属性被业务修改，定时批量处理主表，以维持主表name属性与从表一致 

二、表结构

1、主表 Student

2、从表 Boy

三、建表SQL（DDL）

  1、主表 Student

 1 -- DDL
 2 CREATE TABLE student (
 3 id NUMBER NOT NULL ,
 4 name VARCHAR2(255 BYTE) NULL ,
 5 sex VARCHAR2(255 BYTE) NULL
 6 )
 7  
 8 ALTER TABLE student ADD CHECK (id IS NOT NULL);
 9  
10 -- DML
11 INSERT INTO student VALUES ('1', 'zhangsan', 'boy');
12 INSERT INTO student VALUES ('2', 'lisi', 'girl');
13 INSERT INTO student VALUES ('3', 'wangwu', 'boy');

 2、从表 Boy

1 -- DDL
2 CREATE TABLE boy (
3 id NUMBER NOT NULL ,
4 name VARCHAR2(255 BYTE) NULL
5 )
6  
7 -- DML
8 INSERT INTO boy VALUES ('1', '张三');
9 INSERT INTO boy VALUES ('3', '王五');

四、DML

  1、基本语法

1 -- DML
2 UPDATE student s SET s.name = '张三' WHERE   id = 1; 

  2、变相

1  -- DML，0.015s
2 UPDATE student s
3 SET s.name = (
4   SELECT b.name FROM boy b WHERE s.id = b.id AND s.name != b.name
5 )
6 WHERE EXISTS (
7   SELECT 1 FROM boy b WHERE s.id = b.id AND s.name != b.name
8 );
9  

3、快速游标法

 1  -- DML，0.014s
 2 BEGIN
 3   FOR cur IN (
 4     SELECT s.id sid, b.name bname
 5   FROM student s, boy b
 6   WHERE s.id = b.id AND s.name != b.name AND s.sex = 'boy'
 7   ) loop 
 8  
 9   UPDATE student s SET s.name = cur.bname WHERE s.id = cur.sid;
10   
11   END loop ;
12 END ;
13  

4、内联视图法（inline View）

 1  -- DML，0.019s
 2 UPDATE (
 3   SELECT
 4     s.name sname, b.name bname
 5  FROM
 6     student s, boy b
 7  WHERE
 8     s.id = b.id AND s.name != b.name
 9 )
10 SET sname = bname;
11  

  报错提示：ORA-01779: 无法修改与非键值保存表对应的列

    参考资料，从表id必须增加主键约束，且为视图内的where条件：

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

  5、合并法（Merge）

1 MERGE INTO student s USING boy b ON (
2  s.id = b.id AND s.sex = 'boy' AND s.name != b.name
3 )
4 WHEN MATCHED THEN
5  UPDATE SET s.name = b.name;  

报错提示：ORA-38104: 无法更新 ON 子句中引用的列

    参考资料，错误原因是条件重复，正确写法：

1  -- DML，0.016s
2 MERGE INTO student s USING boy b ON (
3  s.id = b.id AND s.sex = 'boy'
4 --   AND s.name != b.name
5 )
6 WHEN MATCHED THEN
7  UPDATE SET s.name = b.name;  

6、子查询关联

1 update service cs set (cs.customer_id,cs.customer_code,cs.customer_name)=  
2  (
3      select ccb.customer_id,ccb.customer_code,ccb.customer_name from customer_base ccb 
4      inner join customer_contact ccc
5      on ccb.customer_id=ccc.customer_id 
6      where ccc.key_='1' and ccc.value_=cs.value_ and rownum<2
7  )
8  where customer_id='0' and start_time>sysdate-30