- SQL code
-
-- 使用Merge来判断是插入还修改
CREATE TABLE T124
(
ID NUMBER(4),
F1 VARCHAR2(20),
F2 VARCHAR2(20)
);
INSERT INTO T124 VALUES(1, 'A', 'AA');
INSERT INTO T124 VALUES(2, 'B', 'BB');
INSERT INTO T124 VALUES(3, 'C', 'CC');
实测结果：
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CREATETABLE Tbl123( ID1NUMBER(4), ID2VARCHAR2(20), ID3VARCHAR2(20) );INSERTINTO Tbl123 VALUES(1,'A','123');INSERTINTO Tbl123 VALUES(2,'B','1234');INSERTINTO Tbl123 VALUES(3,'C','123123');commit; declare sSqlvarchar2(3000); iCountnumber; v_ID1number; v_ID2varchar2(20); v_ID3varchar2(20);begin iCount :=0; v_ID1 :=1; v_ID3 :='wee'; sSql :='begin select count(*) into :1 from Tbl123 where Id1 = :2; end;'; execute immediate sSql using out iCount,in v_ID1; if iCount > 0then sSql :='begin select distinct Id2 into :1 from Tbl123 where Id1 = :2 and rownum = 1; end;'; execute immediate sSql using out v_ID2,in v_ID1; sSql :='begin update Tbl123 set Id3 = :1 where Id1 = :2 and Id2 = :3; end;'; execute immediate sSql usingin v_ID3,in v_ID1,in v_ID2; dbms_output.put_line('update'); else sSql :='begin insert into Tbl123(Id1,ID2,Id3) values (:1,:2,:3); end;'; execute immediate sSql usingin v_ID1,in v_ID2,in v_ID3; dbms_output.put_line('insert'); end if; commit;exception when others then dbms_output.put_line('Error');end;select* from Tbl123;
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Merge into dept_2 d using dept deon(d.id=de.id)when matchedthenupdatesetd.name=de.namewhennot matchedtheninsert (id,name)values (de.id,de.name);-- 解释-- *1). Merge into dept_2 d using dept de -- 从源表 dept (别名 de) 往 dept_2 表（别名d)中插入或更新数据-- *2). on(d.id=de.id) ：源表(dept)与目标表(dept_2)的连接条件是 (dept_2.id=dept.id)-- *3). when matched then update set d.name=de.name-- 当目标表找到与源表匹配的记录行(匹配条件：dept_2.id=dept.id )，-- 则更新目标表(dept_2) 的 name字段值为 源表 (dept) 的name字段值-- *4). when not matched then insert (id,name) values (de.id,de.name)-- 如果没有找到匹配记录(即：源表记录的id字段值，在目标表中不存在)，-- 则将源表中这样的记录插入目标表-- 简单理解为一句话：有：则更新；无：则插入！