数据库开发.ppt

select null+1 select abc+123 select +123 select null+123 select * from T_Employee where FName null select * from T_Employee where FName is null; select * from T_Employee where FName is not null; select * from T_Employee where FAge 23 or FAge 25 or FAge 28 select * from T_Employee where FAge in 23,25,28 select * from T_Employee where FAge 20 and FAge 30 select * from T_Employee where FAge between 20 and 30 WHERE子句从数据源中去掉不符合其有哪些信誉好的足球投注网站条件的数据 GROUP BY子句搜集数据行到各个组中，统计函数为各个组计算统计值 SELECT FAge,Count * FROM T_Employee where Count * 1 GROUP BY Fage;//聚合函数不应出现在WHERE 子句中 SELECT FAge,Count * FROM T_Employee GROUP BY Fage Having Count * 1 select FAge,Count * FROM T_Employee where FSalary 2000 GROUP BY Fage; select FAge,Count * FROM T_Employee GROUP BY Fage having FSalary 2000 //错，having是对分组后信息的过滤，能用的列和select中能用的列是一样。 //having无法代替where。 ALTER TABLE T_Employee ADD FSubCompany VARCHAR 20 ; ALTER TABLE T_Employee ADD FDepartment VARCHAR 20 ; UPDATE T_Employee SET FSubCompany Beijing,FDepartment Development WHERE FNumber DEV001; UPDATE T_Employee SET FSubCompany ShenZhen,FDepartment Development WHERE FNumber DEV002; UPDATE T_Employee SET FSubCompany Beijing,FDepartment HumanResource WHERE FNumber HR001; UPDATE T_Employee SET FSubCompany Beijing,FDepartment HumanResource WHERE FNumber HR002; UPDATE T_Employee SET FSubCompany Beijing,FDepartment InfoTech WHERE FNumber IT001; UPDATE T_Employee SET FSubCompany ShenZhen,FDepartment InfoTech WHERE FNumber IT002; UPDATE T_Employee SET FSubCompany Beijing,FDepartment Sales WHERE FNumber SALES001; UPDATE T_Employee SET FSubCompany Beijing,FDepartment Sales WHERE FNumber SALES002; UPDATE T_Employee SET FSubCompany ShenZhen,FDepartment Sales WHERE FNumber SALES003; CREATE TABLE T_TempEmployee FIdCardNumber VARCHAR 20 ,FName VARCHAR 20 ,FAge INT, PRIMARY KEY FIdCardNumber ; INSERT INTO T_TempEmployee FIdCardNumber,FName,FAge VALUES 1XXXXXXXXXX21,Sarani,33 ; INSERT INTO T_TempEmployee FIdCardNumber,FName,F