SELECT *,ROWNUM ---- ◆◆◆此语句 ※ 写法不正确
FROM LSSJ_K000_0719
WHERE ROWNUM<100
SELECT t.*,ROWNUM ----此语句可正确执行
FROM LSSJ_K000_0719 t
WHERE ROWNUM<100
SELECT t.*,ROWNUM as rid ----此语句可正确执行
FROM LSSJ_K000_0719 t
WHERE ROWNUM<20
SELECT *,ROWID ---- ◆◆◆此语句 ※ 写法不正确
FROM LSSJ_K000_0719
SELECT t.*,ROWNUM as rid ---- ★★此语句 ☆不正确
FROM LSSJ_K000_0719 t
WHERE ROWNUM BETWEEN 10 AND 20
SELECT t.*,ROWNUM as rid ---- ★★此语句 ☆不正确
FROM LSSJ_K000_0719 t
WHERE ROWNUM >10 AND ROWNUM <20 上面的语句我曾经验证并用过。 不知道以下这两个Select语句有何作用? 其中的“CONNECT BY ROWNUM < 151”是什么意思?
我第一次见到。请高手指点,非常感谢!-----------------------------------
SELECT COUNT(*) FROM dual CONNECT BY ROWNUM < 151;
---- 查询结果为 150
select level as id from dual connect by level < 102;
---- 查询结果为:
ID
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FROM LSSJ_K000_0719
WHERE ROWNUM<100
SELECT t.*,ROWNUM ----此语句可正确执行
FROM LSSJ_K000_0719 t
WHERE ROWNUM<100
SELECT t.*,ROWNUM as rid ----此语句可正确执行
FROM LSSJ_K000_0719 t
WHERE ROWNUM<20
SELECT *,ROWID ---- ◆◆◆此语句 ※ 写法不正确
FROM LSSJ_K000_0719
SELECT t.*,ROWNUM as rid ---- ★★此语句 ☆不正确
FROM LSSJ_K000_0719 t
WHERE ROWNUM BETWEEN 10 AND 20
SELECT t.*,ROWNUM as rid ---- ★★此语句 ☆不正确
FROM LSSJ_K000_0719 t
WHERE ROWNUM >10 AND ROWNUM <20 上面的语句我曾经验证并用过。 不知道以下这两个Select语句有何作用? 其中的“CONNECT BY ROWNUM < 151”是什么意思?
我第一次见到。请高手指点,非常感谢!-----------------------------------
SELECT COUNT(*) FROM dual CONNECT BY ROWNUM < 151;
---- 查询结果为 150
select level as id from dual connect by level < 102;
---- 查询结果为:
ID
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有个例子给你
CREATE TABLE TBL_TEST
(
ID NUMBER,
NAME VARCHAR2(100),
PID NUMBER DEFAULT 0
);INSERT INTO TBL_TEST(ID,NAME,PID) VALUES(1,'10',0);INSERT INTO TBL_TEST(ID,NAME,PID) VALUES(2,'11',1);INSERT INTO TBL_TEST(ID,NAME,PID) VALUES(3,'20',0);INSERT INTO TBL_TEST(ID,NAME,PID) VALUES(4,'12',1);INSERT INTO TBL_TEST(ID,NAME,PID) VALUES(5,'121',2);--从Root往树末梢递归(中序遍历)
select * from TBL_TEST
start with id=1
connect by prior id = pid--从末梢往树ROOT递归(id到ROOT的路径)
select * from TBL_TEST
start with id=5
connect by prior pid = id