SQL Server判断是否满足日期格式（YYYYMMDD）以及中文等判断：

在做sql数据的正确性审核中，需要判断数据是否满足日期格式，网上找不到相关的资料，于是自己花了半天写了一个简单的函数

具体思路：

1.判断字符串是否8位

2.如果是8位，通过datalength判断是否8位，如果不是8位，说明字符串中存在汉字或者不可见字符

3.通过Ascii码对8位中的每一位字符进行判断，目的是判断是否数字（按照AsciI码可以避免不可见字符）

4.如果符合上述3中条件，说明字符是8位的数字，判断是否正常日期

ALTER FUNCTION [dbo].[isDataYYYYMMDD]( @Number nvarchar(50))
RETURNS int
AS
begin
　　if LEN(ltrim(rtrim(@Number)))<>8 or CHARINDEX('.',@Number)>0 or CHARINDEX('#',@Number)>0 or CHARINDEX('*',@Number)>0 or CHARINDEX('-',@Number)>0 or 　　　　CHARINDEX('\',@Number)>0 or CHARINDEX('/',@Number)>0
　　　　begin
　　　　　　return 1
　　　　end
　　else if datalength(ltrim(rtrim(@Number)))<> 8
　　　　if ascii(left(@Number,1))> 57 or ascii(left(@Number,1))<48
　　　　　　or ascii(right(left(@Number,2),1))> 57 or ascii(right(left(@Number,2),1))<48
　　　　　　or ascii(right(left(@Number,3),1))> 57 or ascii(right(left(@Number,3),1))<48
　　　　　　or ascii(right(left(@Number,4),1))> 57 or ascii(right(left(@Number,4),1))<48
　　　　　　or ascii(right(left(@Number,5),1))> 57 or ascii(right(left(@Number,5),1))<48
　　　　　　or ascii(right(left(@Number,6),1))> 57 or ascii(right(left(@Number,6),1))<48
　　　　　　or ascii(right(left(@Number,7),1))> 57 or ascii(right(left(@Number,7),1))<48
　　　　　　or ascii(right(left(@Number,8),1))> 57 or ascii(right(left(@Number,8),1))<48
　　　　　　begin
　　　　　　　　return 1
　　　　　　end
　　　　else
　　　　　　begin
　　　　　　　　return 0
　　　　　　end
　　else
　　　　begin
　　　　　　if DATENAME ( year ,@Number)>2017
　　　　　　　　begin
　　　　　　　　　　return 1
　　　　　　　　end
　　　　　　else if DATENAME ( month ,@Number)>12 or DATENAME ( month ,@Number)<1
　　　　　　　　begin
　　　　　　　　　　return 1
　　　　　　　　end
　　　　　　else if DATENAME ( DAY ,@Number)>31 or DATENAME ( DAY ,@Number)<1
　　　　　　　　begin
　　　　　　　　　　return 1
　　　　　　　　end
　　　　end
　　return 0
end

2.格式化为YYYY-MM-DD

去掉0:20170909:2017-9-9

ALTER FUNCTION [dbo].[formatTime]( @Number nvarchar(500))
RETURNS nvarchar(500)
--返回-1，表示字符串存在问题
--else返回其计算结果
AS
begin
--判断非法字符
if PATINDEX('%[^0123456789]%', @Number)>0
begin
return @Number
end
--如果长度小于4位，eg：2004，200，就直接返回
else if len(@Number)<=4
begin
return @Number
end
--如果长度为5位，eg：20045，返回2004-5
else if len(@Number)=5
begin
if right(@Number,1)='0'
begin
return left(@Number,4)
end
else
begin
return left(@Number,4)+'-'+right(@Number,1)
end
end
--如果长度为6位
else if len(@Number)=6
begin
if right(@Number,2)<='12'
begin
if left(right(@Number,2),1)='0'
begin
return left(@Number,4)+'-'+right(@Number,1)
end
else
begin
return left(@Number,4)+'-'+right(@Number,2)
end
end
else
begin
if right(@Number,1)='0'
begin
return left(@Number,4)+'-'+left(right(@Number,2),1)
end
else
begin
return left(@Number,4)+'-'+left(right(@Number,2),1)+'-'+right(@Number,1)
end
end
end
--如果长度为7位
else if len(@Number)=7
begin
--第5,6位组合起来，小于12 eg:2015111 2015-11-1
if left(right(@Number,3),2)<='12'
begin
if left(right(@Number,3),1)='0' and right(@Number,1)<>'0'
begin
return left(@Number,4)+'-'+left(right(@Number,2),1)+'-'+right(@Number,1)
end
else if left(right(@Number,3),1)='0' and right(@Number,1)='0'
begin
return left(@Number,4)+'-'+left(right(@Number,2),1)
end
else if left(right(@Number,3),1)<>'0' and right(@Number,1)='0'
begin
return left(@Number,4)+'-'+left(right(@Number,3),2)
end
else
begin
return left(@Number,4)+'-'+left(right(@Number,3),2)+'-'+right(@Number,1)
end
end
--第5,6位组合起来大于12，且第6,7位小于31， eg:2015211 2015-2-11
else if left(right(@Number,3),2)>'12' and right(@Number,2)<='31'
begin
if right(@Number,2)='00'
begin
return left(@Number,4)+'-'+left(right(@Number,3),1)
end
else if left(right(@Number,2),1)='0'
begin
return left(@Number,4)+'-'+left(right(@Number,3),1)+'-'+right(@Number,1)
end
end
--第5,6位组合起来大于12，且第6,7位大于31， eg:2015235 不合理
else
return @Number
end
--如果长度为8位
else if len(@Number)=8
begin
if left(right(@Number,4),2)<='12' and right(@Number,2)<='31'
begin
if left(right(@Number,4),2)='00' or right(@Number,2)='00'
begin
return @Number
end
else if left(right(@Number,4),1)='0' and left(right(@Number,2),1)='0'
begin
return left(@Number,4)+'-'+left(right(@Number,3),1)+'-'+right(@Number,1)
end
else if left(right(@Number,4),1)='0' and left(right(@Number,2),1)<>'0'
begin
return left(@Number,4)+'-'+left(right(@Number,3),1)+'-'+right(@Number,2)
end
else if left(right(@Number,4),1)<>'0' and left(right(@Number,2),1)='0'
begin
return left(@Number,4)+'-'+left(right(@Number,4),2)+'-'+right(@Number,1)
end
else
return left(@Number,4)+'-'+left(right(@Number,4),2)+'-'+right(@Number,2)
end
else --不合法
begin
return @Number
end
end
else --不合法
begin
return @Number
end
return '0'
end

不去0:20170909:2017-09-09

ALTER FUNCTION [dbo].[formatTime1]( @Number nvarchar(500))
RETURNS nvarchar(500)
--返回-1，表示字符串存在问题
--else返回其计算结果
AS
begin
--判断非法字符
if PATINDEX('%[^0123456789]%', @Number)>0
begin
return @Number
end
--如果长度小于4位，eg：2004，200，就直接返回
else if len(@Number)<=4
begin
return @Number
end
--如果长度为5位，eg：20045，返回2004-5
else if len(@Number)=5
begin
return left(@Number,4)+'-'+right(@Number,1)
end
--如果长度为6位
else if len(@Number)=6
begin
if right(@Number,2)<='12'
begin
return left(@Number,4)+'-'+right(@Number,2)
end
else
begin
return left(@Number,4)+'-'+left(right(@Number,2),1)+'-'+right(@Number,1)
end
end
--如果长度为7位
else if len(@Number)=7
begin
--第5,6位组合起来，小于12 eg:2015111 2015-11-1
if left(right(@Number,3),2)<='12'
begin
return left(@Number,4)+'-'+left(right(@Number,3),2)+'-'+right(@Number,1)
end
--第5,6位组合起来大于12，且第6,7位小于31， eg:2015211 2015-2-11
else if left(right(@Number,3),2)>'12' and left(@Number,2)<='31'
begin
return left(@Number,4)+'-'+left(right(@Number,3),1)+'-'+right(@Number,2)
end
--第5,6位组合起来大于12，且第6,7位大于31， eg:2015235 不合理
else
return @Number
end
--如果长度为8位
else if len(@Number)=8
begin
if left(right(@Number,4),2)<='12' and right(@Number,2)<='31'
begin
return left(@Number,4)+'-'+left(right(@Number,4),2)+'-'+right(@Number,2)
end
else --不合法
begin
return @Number
end
end
else --不合法
begin
return @Number
end
return '0'
end