bitsCN.com
one:
declare @s varchar(20)
declare @i varchar(20)
set @i=''
set @s='新会员必须购买350元产品'
while PATINDEX ('%[0-9]%', @s)>0
begin
set @i=@i+substring(@s,PATINDEX ('%[0-9]%', @s),1)
set @s=stuff(@s,1,PATINDEX ('%[0-9]%', @s),'')
end
select @i
--
300
two:
declare @a table(id int identity(1,1),a varchar(100))
insert @a select '新会员必须购买350元产品'
union all select '新店首次定货必须满20000元'
select left(right(a,len(a)-patindex('%[0-9]%',a)+1),len(right(a,len(a)-patindex('%[0-9]%',a)+1))-1) from @a
上在的
select substring(所查询字符串,patindex('%[^0-9][0-9]%',所查询字符串)+1,patindex('%[0-9][^0-9]%',所查询字符串)-patindex('%[^0-9][0-9]%',所查询字符串)) 这个只能查询第一次在字符串出现的数字串
那么如果出现字符串什么样子的呢 sss8989sss http://www.hzhuti.com ss8989ss8989ss8989 7879aafds789 432432432543534 应该怎么取呢
实例
代码如下 复制代码
create function fn_GetNum(@s varchar(8000))
returns varchar(8000)
as
begin
select @s = stuff(stuff(@s, 1, patindex('%[0-9, .]%', @s) - 1, ''),
patindex('%[^0-9, .]%', stuff(@s, 1, patindex('%[0-9, .]%', @s) - 1, '')),
len(@s), '')
return @s
end
declare @t table(s varchar(8000))
insert @t select 'aaa11112bbb'
union all select 'ccc212sss'
union all select 'sss21a'
select dbo.fn_GetNum(s) as result from @t
select substring(s,patindex('%[^0-9][0-9]%',s)+1,patindex('%[0-9][^0-9]%',s)-patindex('%[^0-9][0-9]%',s)) from @t
/*功能:获取字符串中的字母*/
CREATE FUNCTION dbo.F_Get_STR (@S VARCHAR(100))
RETURNS VARCHAR(100)
AS
BEGIN
WHILE PATINDEX('%[^a-z]%',@S)>0
BEGIN
set @s=stuff(@s,patindex('%[^a-z]%',@s),1,'')
END
RETURN @S
END
GO
--测试
select dbo.F_Get_STR('测试ABC123ABC')
GO
/*
功能:获取字符串中的数字
*/
create function dbo.F_Get_Number (@S varchar(100))
returns int
AS
begin
while PATINDEX('%[^0-9]%',@S)>0
begin
set @s=stuff(@s,patindex('%[^0-9]%',@s),1,'')
end
return cast(@S as int)
end
--测试
---select dbo.F_Get_Number('测试AB3C123AB5C')
GO
这样之后不管你是那种组合我们都可以方便的把字符中的数字全部取出来。
更多详细内容请查看:http://www.111cn.net/database/mssqlserver/42376.htm
bitsCN.com
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MySQL index cardinality has a significant impact on query performance: 1. High cardinality index can more effectively narrow the data range and improve query efficiency; 2. Low cardinality index may lead to full table scanning and reduce query performance; 3. In joint index, high cardinality sequences should be placed in front to optimize query.

The MySQL learning path includes basic knowledge, core concepts, usage examples, and optimization techniques. 1) Understand basic concepts such as tables, rows, columns, and SQL queries. 2) Learn the definition, working principles and advantages of MySQL. 3) Master basic CRUD operations and advanced usage, such as indexes and stored procedures. 4) Familiar with common error debugging and performance optimization suggestions, such as rational use of indexes and optimization queries. Through these steps, you will have a full grasp of the use and optimization of MySQL.

MySQL's real-world applications include basic database design and complex query optimization. 1) Basic usage: used to store and manage user data, such as inserting, querying, updating and deleting user information. 2) Advanced usage: Handle complex business logic, such as order and inventory management of e-commerce platforms. 3) Performance optimization: Improve performance by rationally using indexes, partition tables and query caches.


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