數(shù)據(jù)分組
數(shù)據(jù)分組
select count(*) from T_Employee
select FAge,count(*) from T_Employee
Group by FAge;
select FAge,avg(FSalary)from T_Employee
Group by FAge;
Having的用法
注意：Having是對(duì)分組以后的數(shù)據(jù)進(jìn)行過濾的，Where是對(duì)原始的數(shù)據(jù)進(jìn)行過濾。
Having的用法
