课堂笔记

第四章练习题--练习1SELECT ename,initcap(ename),length(ename)FROM empWHERE substr(ename,1,1) IN('J','A','M')--练习2SELECT ename FROM empWHERE instr(lower(ename),'a',1)>0SELECT ename,length(ename)FROM empWHERE deptno IN(10,20)AND hiredate > '1-5月-81'AND instr(ename,'A',1)>0SELECT lpad(deptno,10,'*') || lpad(ename,10,'*') || rpad(sal,10,'*')FROM emp--练习3SELECT round(100.456,2),round(100.456,1),round(100.456,0) FROM dualSELECT trunc(100.456,2),trunc(100.456,1),trunc(100.456,0) FROM dual--练习4SELECT ename,SYSDATE-hiredateFROM emp2001199520011995--练习5SELECT SYSDATE FROM dualSELECT ROUND(months_betWeen('1-1月-00',hiredate),0) working,extract(MONTH FROM HIREDATE) comingFROM empWHERE deptno IN(10,20)