sqlserver 基礎知識 數(shù)據(jù)檢索、查詢排序語句，需要的朋友可以參考下。
代碼如下:
–執(zhí)行順序 From Where Select
select * from
(select sal as salary,comm as commission from emp ) x where salary–得出 Name Work as a Job
select ename +’ Work as a’+job as msg from emp where deptno=10
–如果員工工資小于2000返回UnderPaid 大于等于4k 返回OverPaid 之間返回OK
select ename,sal,
case when salwhen sal>=4000 then ‘OverPaid’
else
‘OK’
end
from emp
–從表中隨機返回N條記錄 newid()
–order by 字句中指定數(shù)字常量時，是要求根據(jù)select列表中相應位置的列排序
–order by 字句中用函數(shù)時，則按函數(shù)在沒一行計算結(jié)果排序
select top 5 ename from emp order by newid()
–找空值is null
select * from emp where comm is null
–將空值轉(zhuǎn)換為實際值
–解釋：返回其參數(shù)中第一個非空表達式
–coalesce 聯(lián)合，合并，結(jié)合.英音：[,k?u?’les]美音：[,ko?’l?s]
select coalesce(comm, 1),empNo from emp
–按模式搜索
–返回匹配特定子串或模式的行
select ename,job
from emp
where deptno in(10,20)
–按子串排序 按照職位字段的 最后兩個字符排序
select ename, job from emp order by substring(job,len(job)-2,2)
–select top 2 len(job)-2 from emp
–select top 2 job from emp
–☆☆☆☆☆處理排序空值☆☆☆☆☆ [只能是大于0]
select ename ,sal,comm
from emp
order by 1 desc
— 以降序或升序方式排序非空值，將空值放到最后，可以用case
select ename,sal,comm from
(
select ename ,sal,comm ,
case when comm is null then 0 else 1 end as A
from emp
) x
order by A desc ,comm desc
