SQL Server 替换，删除特定字符后的所有内容
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/1668014/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
SQL Server replace, remove all after certain character
提问by Jimmy
My data looks like
我的数据看起来像
ID MyText
1 some text; some more text
2 text again; even more text
How can I update MyText to drop everything after the semi-colon and including the semi colon, so I'm left with the following:
如何更新 MyText 以删除分号之后的所有内容并包括分号，所以我只剩下以下内容：
ID MyText
1 some text
2 text again
I've looked at SQL Server Replace, but can't think of a viable way of checking for the ";"
我看过SQL Server Replace，但想不出一种可行的方法来检查“;”
回答by Paul Williams
Use LEFT combined with CHARINDEX:
将 LEFT 与 CHARINDEX 结合使用：
UPDATE MyTable
SET MyText = LEFT(MyText, CHARINDEX(';', MyText) - 1)
WHERE CHARINDEX(';', MyText) > 0
Note that the WHERE clause skips updating rows in which there is no semicolon.
请注意，WHERE 子句会跳过更新没有分号的行。
Here is some code to verify the SQL above works:
下面是一些验证上述 SQL 工作的代码：
declare @MyTable table ([id] int primary key clustered, MyText varchar(100))
insert into @MyTable ([id], MyText)
select 1, 'some text; some more text'
union all select 2, 'text again; even more text'
union all select 3, 'text without a semicolon'
union all select 4, null -- test NULLs
union all select 5, '' -- test empty string
union all select 6, 'test 3 semicolons; second part; third part;'
union all select 7, ';' -- test semicolon by itself
UPDATE @MyTable
SET MyText = LEFT(MyText, CHARINDEX(';', MyText) - 1)
WHERE CHARINDEX(';', MyText) > 0
select * from @MyTable
I get the following results:
我得到以下结果：
id MyText
-- -------------------------
1 some text
2 text again
3 text without a semicolon
4 NULL
5 (empty string)
6 test 3 semicolons
7 (empty string)
回答by Rashlien
For the times when some fields have a ";" and some do not you can also add a semi-colon to the field and use the same method described.
对于某些字段有“;”的时候 有些没有，您还可以在字段中添加分号并使用所描述的相同方法。
SET MyText = LEFT(MyText+';', CHARINDEX(';',MyText+';')-1)
回答by Rookie
Could use CASE WHENto leave those with no ';' alone.
可以CASE WHEN用来离开那些没有';' 独自的。
SELECT
CASE WHEN CHARINDEX(';', MyText) > 0 THEN
LEFT(MyText, CHARINDEX(';', MyText)-1) ELSE
MyText END
FROM MyTable
回答by David
Use CHARINDEXto find the ";". Then use SUBSTRINGto just return the part before the ";".
使用CHARINDEX找到“;”。然后用于SUBSTRING仅返回“;”之前的部分。
回答by manji
UPDATE MyTable
SET MyText = SUBSTRING(MyText, 1, CHARINDEX(';', MyText) - 1)
WHERE CHARINDEX(';', MyText) > 0
回答by gotqn
For situations when I need to replace or match(find) something against string I prefer using regular expressions.
对于需要替换或匹配（查找）字符串的情况，我更喜欢使用正则表达式。
Since, the regular expressions are not fully supported in T-SQLyou can implement them using CLRfunctions. Furthermore, you do not need any C#or CLRknowledge at all as all you need is already available in the MSDN String Utility Functions Sample.
由于不完全支持正则表达式，T-SQL您可以使用CLR函数来实现它们。此外，您根本不需要任何知识C#或CLR知识，因为您需要的所有内容都已在 MSDN字符串实用程序函数示例 中可用。
In your case, the solution using regular expressions is:
在您的情况下，使用正则表达式的解决方案是：
SELECT [dbo].[RegexReplace] ([MyColumn], '(;.*)', '')
FROM [dbo].[MyTable]
But implementing such function in your database is going to help you solving more complex issues at all.
但是在您的数据库中实现这样的功能将帮助您解决更复杂的问题。
The example below shows how to deploy only the [dbo].[RegexReplace]function, but I will recommend to you to deploy the whole String Utilityclass.
下面的例子展示了如何只部署[dbo].[RegexReplace]函数，但我会建议你部署整个String Utility类。
Enabling CLR Integration. Execute the following Transact-SQL commands:
sp_configure 'clr enabled', 1 GO RECONFIGURE GOBulding the code (or creating the
.dll). Generraly, you can do this using the Visual Studio or .NET Framework command prompt (as it is shown in the article), but I prefer to use visual studio.create new class library project:
copy and paste the following code in the
Class1.csfile:using System; using System.IO; using System.Data.SqlTypes; using System.Text.RegularExpressions; using Microsoft.SqlServer.Server; public sealed class RegularExpression { public static string Replace(SqlString sqlInput, SqlString sqlPattern, SqlString sqlReplacement) { string input = (sqlInput.IsNull) ? string.Empty : sqlInput.Value; string pattern = (sqlPattern.IsNull) ? string.Empty : sqlPattern.Value; string replacement = (sqlReplacement.IsNull) ? string.Empty : sqlReplacement.Value; return Regex.Replace(input, pattern, replacement); } }build the solution and get the path to the created
.dllfile:replace the path to the
.dllfile in the followingT-SQLstatements and execute them:IF OBJECT_ID(N'RegexReplace', N'FS') is not null DROP Function RegexReplace; GO IF EXISTS (SELECT * FROM sys.assemblies WHERE [name] = 'StringUtils') DROP ASSEMBLY StringUtils; GO DECLARE @SamplePath nvarchar(1024) -- You will need to modify the value of the this variable if you have installed the sample someplace other than the default location. Set @SamplePath = 'C:\Users\gotqn\Desktop\StringUtils\StringUtils\StringUtils\bin\Debug\' CREATE ASSEMBLY [StringUtils] FROM @SamplePath + 'StringUtils.dll' WITH permission_set = Safe; GO CREATE FUNCTION [RegexReplace] (@input nvarchar(max), @pattern nvarchar(max), @replacement nvarchar(max)) RETURNS nvarchar(max) AS EXTERNAL NAME [StringUtils].[RegularExpression].[Replace] GOThat's it. Test your function:
declare @MyTable table ([id] int primary key clustered, MyText varchar(100)) insert into @MyTable ([id], MyText) select 1, 'some text; some more text' union all select 2, 'text again; even more text' union all select 3, 'text without a semicolon' union all select 4, null -- test NULLs union all select 5, '' -- test empty string union all select 6, 'test 3 semicolons; second part; third part' union all select 7, ';' -- test semicolon by itself SELECT [dbo].[RegexReplace] ([MyText], '(;.*)', '') FROM @MyTable select * from @MyTable
启用 CLR 集成。执行以下 Transact-SQL 命令：
sp_configure 'clr enabled', 1 GO RECONFIGURE GO构建代码（或创建
.dll）。通常，您可以使用 Visual Studio 或 .NET Framework 命令提示符（如文章中所示）执行此操作，但我更喜欢使用 Visual Studio。创建新的类库项目：
将以下代码复制并粘贴到
Class1.cs文件中：using System; using System.IO; using System.Data.SqlTypes; using System.Text.RegularExpressions; using Microsoft.SqlServer.Server; public sealed class RegularExpression { public static string Replace(SqlString sqlInput, SqlString sqlPattern, SqlString sqlReplacement) { string input = (sqlInput.IsNull) ? string.Empty : sqlInput.Value; string pattern = (sqlPattern.IsNull) ? string.Empty : sqlPattern.Value; string replacement = (sqlReplacement.IsNull) ? string.Empty : sqlReplacement.Value; return Regex.Replace(input, pattern, replacement); } }构建解决方案并获取创建
.dll文件的路径：替换
.dll以下T-SQL语句中的文件路径并执行它们：IF OBJECT_ID(N'RegexReplace', N'FS') is not null DROP Function RegexReplace; GO IF EXISTS (SELECT * FROM sys.assemblies WHERE [name] = 'StringUtils') DROP ASSEMBLY StringUtils; GO DECLARE @SamplePath nvarchar(1024) -- You will need to modify the value of the this variable if you have installed the sample someplace other than the default location. Set @SamplePath = 'C:\Users\gotqn\Desktop\StringUtils\StringUtils\StringUtils\bin\Debug\' CREATE ASSEMBLY [StringUtils] FROM @SamplePath + 'StringUtils.dll' WITH permission_set = Safe; GO CREATE FUNCTION [RegexReplace] (@input nvarchar(max), @pattern nvarchar(max), @replacement nvarchar(max)) RETURNS nvarchar(max) AS EXTERNAL NAME [StringUtils].[RegularExpression].[Replace] GO就是这样。测试你的功能：
declare @MyTable table ([id] int primary key clustered, MyText varchar(100)) insert into @MyTable ([id], MyText) select 1, 'some text; some more text' union all select 2, 'text again; even more text' union all select 3, 'text without a semicolon' union all select 4, null -- test NULLs union all select 5, '' -- test empty string union all select 6, 'test 3 semicolons; second part; third part' union all select 7, ';' -- test semicolon by itself SELECT [dbo].[RegexReplace] ([MyText], '(;.*)', '') FROM @MyTable select * from @MyTable
