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

 -- DDL
 CREATE TABLE student (
 id NUMBER NOT NULL ,
 name VARCHAR2( BYTE) NULL ,
 sex VARCHAR2( BYTE) NULL
 )

 ALTER TABLE student ADD CHECK (id IS NOT NULL);

 -- DML
 INSERT INTO student VALUES ('', 'zhangsan', 'boy');
 INSERT INTO student VALUES ('', 'lisi', 'girl');
 INSERT INTO student VALUES ('', 'wangwu', 'boy');

2、从表 Boy

 -- DDL
 CREATE TABLE boy (
 id NUMBER NOT NULL ,
 name VARCHAR2( BYTE) NULL
 )

 -- DML
 INSERT INTO boy VALUES ('', '张三');
 INSERT INTO boy VALUES ('', '王五');

四、DML

1、基本语法

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

2、变相

  -- DML，.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  FROM boy b WHERE s.id = b.id AND s.name != b.name
 );
  

3、快速游标法

  -- DML，.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、内联视图法（inline View）

  -- DML，.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;
  

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：

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

5、合并法（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;  

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：

  -- DML，.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、子查询关联

 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_='' and ccc.value_=cs.value_ and rownum<
  )
  where customer_id='' and start_time>sysdate-