oracle学习笔记（一）分享

1、基本语法
SELECT
from
WHERE
GROUP BY
HAVING
ORDER BY
SELECT:查询的字段
1、可用*表示所有字段。
2、字段之间用逗号分割。
3、可为字段起别名 其别名可写成SELECT AAAA。AA AS SS 或 AAAA。AA SS 可省略as
4、可直接写字段值：如 SELECT AAAA。AA SS,'张三' NAME from 。。。
from:查询的表名
1、表名间用逗号分割
2、可为表起别名 其别名可写成 from AAAA AS T 或 from AAAA T 可省略as
WHERE:查询条件
函数：
NVL
||
SYSDATE
3、连接
连接：左联(+)
自联、内联、外联
4、子查询：
5、合并数据：
UNION
UNION ALL
6、触发器：
例子1：插入主键
CREATE OR REPLACE TRIGGER AA_
BEFORE INSERT ON AA
FOR EACH ROW
DECLARE
BEGIN
SELECT AA_SEQ.NEXTVAL INTO :NEW.AA from DUAL;
END AA_;
例子2：
CREATE OR REPLACE TRIGGER ADDB2B_GHDWUSER
AFTER INSERT ON B2B_GHDWUSER FOR EACH ROW
DECLARE
V_MENUID B2B_GHJBMENU.MENUID%TYPE;
_MENUID VARCHAR2(20);
CURSOR INSERTUMENU IS
SELECT A.MENUID from B2B_GHJBMENU A,XTGHDW B
WHERE A.JNAM = B.JB AND B.DWBM= :NEW.GHDWBM;
V_LXBM XTFBLX.LXBM%TYPE;
CURSOR INSERTLXBM IS
SELECT DISTINCT LXBM from XTFBLX;
BEGIN
OPEN INSERTUMENU;
FETCH INSERTUMENU INTO V_MENUID,_MENUID;
WHILE INSERTUMENU%FOUND LOOP
INSERT INTO B2B_USERMENU (USERBM,MENUID)
VALUES(:NEW.USERBM,V_MENUID);
FETCH INSERTUMENU INTO V_MENUID;
END LOOP;
CLOSE INSERTUMENU;
OPEN INSERTLXBM;
FETCH INSERTLXBM INTO V_LXBM;
WHILE INSERTLXBM%FOUND LOOP
INSERT INTO B2B_USERXX (USERBM,LXBM)
VALUES(:NEW.USERBM,V_LXBM);
FETCH INSERTLXBM INTO V_LXBM;
END LOOP;
CLOSE INSERTLXBM;
IF :OLD.SWBZ='2' AND :NEW.SWBZ = '0' THEN
BEGIN
SELECT TID,FUSED INTO L_ID,L_FUSED from RPC_CONTRAC WHERE HTBM = :NEW.HTBM AND HTLB <> '9';

IF L_FUSED=1 THEN
RAISE_APPLICATION_ERROR(-20005,'不能删除!');
END IF;

DELETE RPC_CONTRACENTRY WHERE TID = L_ID;
DELETE RPC_CONTRAC