回复：数据库系统工程师

--errorSELECT * FROM (SELECT rownum,t.* FROM (SELECT ROWNUM,emp.* FROM emp WHERE ROWNUM<=10) t WHERE ROWNUM>=6)ORDER BY ROWNUM;

--truthSELECT *FROM (SELECT ROWNUM AS row_num, tmp_tab.* FROM (SELECT * FROM emp ORDER BY empno) tmp_tab WHERE ROWNUM <= 10)WHERE row_num >= 6ORDER BY row_num;

SELECT *FROM (SELECT ROWNUM AS row_num, tmp_tab.* FROM (SELECT * FROM emp) tmp_tab WHERE ROWNUM <= 10)WHERE row_num >= 6;

--创建一个函数CREATE OR REPLACE FUNCTION f_func(v_x in varchar2,v_y in number)RETURN NUMBERASv_z number(5);BEGIN SELECT quantity INTO v_z FROM productinfo WHERE productid='1'; RETURN v_z;END;/

--创建一个带有out参数的函数CREATE OR REPLACE FUNCTION f_pric(v_cate in varchar2,v_productprice in out number)RETURN NUMBERASv_quan number;BEGIN IF v_productprice IS NULL THEN v_productprice:=0; END IF; SELECT AVG(productprice),MIN(quantity) INTO v_productprice,v_quan FROM productinfo WHERE category=v_cate AND productprice>v_productprice; RETURN v_quan;EXCEPTION WHEN NO_DATA_FOUND THEN DBMS_OUTPUT.PUT_LINE('没有数据发现'); WHEN TOO_MANY_ROWS THEN DBMS_OUTPUT.PUT_LINE('对应数据太多');END;/

--执行以上函数DECLAREv_productprice varchar2(11):='23';catex varchar2(11):='FRUIT';quanti number;BEGIN quanti:=f_pric(catex,v_productprice); DBMS_OUTPUT.PUT_LINE('平均价格'||v_productprice); DBMS_OUTPUT.PUT_LINE('最低的产品数量是:'||quanti);END;/

--创建表时，忘记了默认表空间！！CREATE TABLE nihao(nihaoid number primary key,nihaoname varchar2(11) not null)DEFAULT TABLESPACE;

--双loop使用批量提取数据DECLARECURSOR pdct_collect_curIS SELECT * FROM productinfo;TYPE pdct_tab IS TABLE OF productinfo%ROWTYPEINDEX BY PLS_INTEGER;pdct_rd pdct_tab;BEGIN OPEN pdct_collect_cur; LOOP FETCH pdct_collect_cur BULK COLLECT INTO pdct_rd LIMIT 3; DBMS_OUTPUT.PUT_LINE('pdct_rd.first='||pdct_rd.first); DBMS_OUTPUT.PUT_LINE('pdct_rd.count='||pdct_rd.count); DBMS_OUTPUT.PUT_LINE('pdct_rd.last='||pdct_rd.last); EXIT WHEN pdct_collect_cur%NOTFOUND; FOR i IN 1..pdct_rd.count LOOP DBMS_OUTPUT.PUT_LINE('产品ID：'||pdct_rd(i).productid|| '产品名称：'||pdct_rd(i).productname|| '产品价格：'||pdct_rd(i).productprice); END LOOP; DBMS_OUTPUT.PUT_LINE('pdct_rd.count='||pdct_rd.count); --EXIT WHEN pdct_collect_cur%NOTFOUND; END LOOP; CLOSE pdct_collect_cur ;END;/

--等待中的更新。UPDATE DALING.productinfo SET productprice=34,quantity=234 WHERE productname='ORANGE';

--为何表或视图不存在呢？貌似先授权select sid,username,blocking_session,blocking_session_status,blocking_instance from V$SESSION where username='DALING';

--ORA-02030: 只能从固定的表/视图查询GRANT SELECT ON V$LOCKED_OBJECT TO daling;

select s.sid from v$session s;

SELECT sid,username,blocking_session,blocking_session_status from v$session where username='DALING';

//加载驱动 try{ Class.forName("oracle.jdbc.driver.OracleDriver"); Connection ct=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:newstar","scott","tiger");}

--创建一个视图CREATE OR REPLACE VIEW pro_viewASSELECT * FROM productinfo;
ALTER VIEW pro_view ADD CONSTRAINT pk_productid UNIQUE(productid) DISABLE NOVALIDATE;