oracle统计每个员工数,oracle按部门统计员工人数

函数查询

注：在oracle中，数字注释需要加双引号“”

select count(*) Total,

sum(decode(to_char(hiredate,’YYYY’),’1980’,’1’,’0’)) “1980”，

sum(decode(to_char(hiredate,’YYYY’),’1981’,’1’,’0’)) “1981” ,

sum(decode(to_char(hiredate,’YYYY’),’1982’,’1’,’0’)) “1982”，

sum(decode(to_char(hiredate,’YYYY’),’1983’,’1’,’0’)) “1983”，

from emp;

子查询：

select (selet coun(*) from emp ) total, (select count(*) from emp where to_char(hiredate,’YYYY’)=’1980’) “1980” , (select count(*) from emp where to_char(hiredate,’YYYY’)=’1981’) “1981” , (select count(*) from emp where to_char(hiredate,’YYYY’)=’1982’) “1982” , (select count(*) from emp where to_char(hiredate,’YYYY’)=’1983’) “1983” from dual ;—oracle自带的伪表