SQL数据库语句整理（Northwind数据库）

1.NEWID()    随机函数，进行随机排序使用

查询某个表的随机排序时使用

SELECT *
FROM Products
ORDER BY NEWID()

2. 通配符

（1） %  代表一个或者任意多个字符

SELECT * FROM Products
WHERE ProductName LIKE ‘A%‘

(2)  _ 代表单个字符

SELECT * FROM Products
WHERE ProductName LIKE ‘Alice Mutto_‘

SELECT * FROM Products
WHERE ProductName LIKE ‘_lice Mutton‘

SELECT * FROM Products
WHERE ProductName LIKE ‘Ali_e Mutton‘

(3) [ ]    指定范围内的单个字符

SELECT * FROM Products
WHERE ProductName LIKE ‘[A,B,C]_[A,B,C]%‘

(4) [^ ]    不在范围内的单个字符

SELECT * FROM Products
WHERE ProductName LIKE ‘[^A,B,C]%[A,B,C]‘

3. ORDER BY

•A. Order By 中可以使用列号

•B. 如果没有指定是升序(ASC)，还是降序(DESC)，缺省为升序(ASC)

•C. 可以对多达16个列执行Order By语句

4. GROUP BY  GROUP BY 后面的字段必须与SELECT后面的一致

SELECT ProductID,ProductName,SUM(UnitPrice)
FROM Products
WHERE ProductID>10
GROUP BY ProductID,ProductName  --与select后面保持一致
HAVING SUM(UnitPrice)>20 --聚合函数之类的需要用having--->类似于where

(1) WITH ROLLUP：每一组求一个结果

(2)WITH CUBE：每一组求一个结果后，所有的也求一个结果

5.临时表

（1）局部临时表 #TABLE

SELECT TOP 10 *
INTO #PRODUCCT_NEW
FROM Products

SELECT * FROM #PRODUCCT_NEW

（2）全局临时表 ##TABLE

SELECT TOP 10 *
INTO ##PRODUCCT_NEW
FROM Products

SELECT * FROM ##PRODUCCT_NEW

DROP TABLE ##PRODUCCT_NEW

（3）Insert Into Table Name Select Column1 ..From..Where..

INSERT INTO Categories
(
CategoryID
,CategoryName
,Description
,Picture
)
(SELECT 10,CategoryName,--这是一个新的值10
N‘这是一个描述‘,Picture
FROM Categories
WHERE CategoryID=‘1‘)

SET IDENTITY_INSERT Categories ON

6. UPDATE   UPDATE…SET…FROM…

UPDATE Products
SET CategoryID=(SELECT TOP 1 CategoryID FROM Categories )
WHERE ProductID=3

7.IF WHILE

(1).

IF 条件

BEGIN … END

ELSE

BEGIN … END

(2)

WHILE 条件

BEGIN

…

END

Declare @i int
Declare @j int
Declare @str varchar(max)
set @i=9
set @j=1
while(@i>=1)
begin
set @str=‘‘
 while(@j<=@i)
     begin
    set @str=@str+CONVERT(varchar,@i)+‘*‘+CONVERT(varchar,@j)+‘=‘+CONVERT(varchar,@i*@j)+‘ ‘
     set @j=@j+1
     end
 print @str
 set @i=@i-1
 set @j=1
end

8. CASE WHEN 语句

SELECT TOP 1000 [EmployeeID]
      ,[LastName]
      ,[FirstName]
      ,[Title]
      ,CASE    [TitleOfCourtesy]
      WHEN ‘Ms.‘ THEN ‘Ms.先生‘
      WHEN ‘Mr.‘ THEN ‘Mr.先生‘
      ELSE ‘未命名‘
      END AS TitleOfCourtesy
  FROM [Northwind].[dbo].[Employees]

SELECT TOP 1000
       CASE WHEN [ProductID]<10 THEN N‘ <10‘
            WHEN [ProductID]>10 and [ProductID]<20 THEN N‘10> <20‘
            ELSE N‘>20‘ END AS [ProductID]
      ,[ProductName]
      ,[SupplierID]
      ,[CategoryID]
      ,[QuantityPerUnit]
      ,[UnitPrice]
      ,[UnitsInStock]
      ,[UnitsOnOrder]
      ,[ReorderLevel]
      ,[Discontinued]
  FROM [Northwind].[dbo].[Products]

9.

(1) Substring()

SELECT SUBSTRING(PRODUCTNAME,0,5)
FROM PRODUCTS WHERE ProductID=5

(2)RTRIM, LTRIM左右缩进

(3) LEN长度

SELECT LEN(ProductName),PRODUCTNAME
FROM PRODUCTS WHERE ProductID=5

(4)RIGHT, LEFT  right()从右边数输出，left（）从左边数输出

SELECT
PRODUCTNAME,LEN(ProductName),
LEFT(PRODUCTNAME,5)
,RIGHT(PRODUCTNAME,3)
FROM PRODUCTS WHERE ProductID=5