merge 合并：有则更新 无则插入
MERGE INTO 目标表USING 源表ON (链接条件)WHEN MATCHED THENUPDATE ...WHEN NOT MATCHED THEN INSERT .. MERGE INTO TAR_GLLZ AUSING GLLZ BON (A.ID = B.ID)WHEN MATCHED THENUPDATE SET A.NAME = B.NAME WHEN NOT MATCHED THEN INSERT (A.ID,A.NAME) VALUES(B.ID,B.NAME);CREATE TABLE GLLZ(ID NUMBER,NAME VARCHAR2(20));INSERT INTO GLLZ VALUES(1,'A');INSERT INTO GLLZ VALUES(2,'B');INSERT INTO GLLZ VALUES(3,'C');SELECT G.*,ROWID FROM GLLZ G;CREATE TABLE TAR_GLLZ AS SELECT * FROM GLLZ WHERE 1 = 2;INSERT INTO TAR_GLLZ VALUES (1,'AA');SELECT * FROM TAR_GLLZ;
开发者涨薪指南 
48位大咖的思考法则、工作方式、逻辑体系
