MySQL中子字符串索引函数的SQL Server等价物
我正在尝试将一个查询从MySQL移植到SQL SERVER 2012。 我如何为MySQL的子字符串索引编写等价物 MySQL在指定的分隔符出现次数之前返回给定字符串中的子字符串 子字符串_INDEXstr，delim，countMySQL中子字符串索引函数的SQL Server等价物,mysql,sql-server-2012,porting,Mysql,Sql Server 2012,Porting,我正在尝试将一个查询从MySQL移植到SQL SERVER 2012。 我如何为MySQL的子字符串索引编写等价物 MySQL在指定的分隔符出现次数之前返回给定字符串中的子字符串 子字符串_INDEXstr，delim，count SELECT SUBSTRING_INDEX('www.somewebsite.com','.',2); 输出：“www.somewebsite”尝试基于T-SQL和XQueryroot/row的此解决方案[position尝试此解决方案 CREATE FUNCTI
SELECT SUBSTRING_INDEX('www.somewebsite.com','.',2);
输出：“www.somewebsite”尝试基于T-SQL和XQueryroot/row的此解决方案[position尝试此解决方案
CREATE FUNCTION SubString_Index
(
@ExistingString NVARCHAR(200),
@BreakPoint NVARCHAR(10),
@number INT
)
RETURNS NVARCHAR(200)
AS
BEGIN
DECLARE @Count INT
DECLARE @Substring NVARCHAR(200)
DECLARE @ssubstring NVARCHAR(200)
SET @ssubstring=@ExistingString
DECLARE @scount INT
SET @scount=0
DECLARE @sscount INT
SET @sscount=0
WHILE(@number>@scount)
BEGIN
Select @Count=CHARINDEX(@BreakPoint,@ExistingString)
Select @ExistingString=SUBSTRING(@ExistingString,@Count+1,LEN(@ExistingString))
Select @scount=@scount+1
select @sscount=@sscount+@Count
END
SELECT @Substring=SUBSTRING(@ssubstring,0,@sscount)
RETURN @Substring
END
GO
select dbo.SubStringIndex('hi.you.com','.',1)
选择dbo.FN\u SUBSTRING\u INDEXN'prueba'，'ue'，-1；我最近需要它，所以我编写了以下存储函数。最后是一系列测试，以确保它与MySql函数完全一样运行。在那里运行相同的测试后，从MySql复制了预期结果：
-- Function to reproduce the useful functionality of SUBSTRING_INDEX from MySql
CREATE FUNCTION dbo.SUBSTRING_INDEX(@InString NVARCHAR(Max),
@Delimiter NVARCHAR(Max),
@Count INT)
RETURNS NVARCHAR(200)
AS
BEGIN
DECLARE @Pos INT;
DECLARE @DelimiterOffsets TABLE
(
i INT IDENTITY(1, 1) NOT NULL,
offset INT NOT NULL
);
-- If @Count is zero, we return '' as per spec
IF @Count = 0
BEGIN
RETURN '';
END;
DECLARE @OrigLength INT = LEN(@InString);
DECLARE @DelimiterLength INT = LEN(@Delimiter);
-- Prime the pump.
SET @Pos = Charindex(@Delimiter, @InString, 1);
-- If the delimiter does not exist in @InString, return the whole string
IF @Pos = 0
BEGIN
RETURN @InString;
END;
-- Put all delimiter offsets into @DelimiterOffsets, they get numbered automatically.
DECLARE @CurrentOffset INT = 0;
WHILE @Pos > 0
BEGIN
SET @CurrentOffset = @Pos;
INSERT INTO @DelimiterOffsets
(offset)
VALUES (@CurrentOffset);
SET @Pos = Charindex(@Delimiter, @InString, @CurrentOffset + @DelimiterLength);
END;
-- This number is guaranteed to be > 0.
DECLARE @DelimitersFound INT = (SELECT Count(*) FROM @DelimiterOffsets);
-- If they requested more delimiters than were found, return the whole string, as per spec.
IF Abs(@Count) > @DelimitersFound
BEGIN
RETURN @InString;
END;
DECLARE @StartSubstring INT = 0;
DECLARE @EndSubstring INT = @OrigLength;
-- OK, now return the part they requested
IF @Count > 0
BEGIN
SET @EndSubstring = (SELECT offset
FROM @DelimiterOffsets
WHERE i = @Count);
END
ELSE
BEGIN
SET @StartSubstring = (SELECT offset + @DelimiterLength
FROM @DelimiterOffsets
WHERE i = (@DelimitersFound + @Count + 1));
END;
RETURN Substring(@InString, @StartSubstring, @EndSubstring);
END;
Go
GRANT EXECUTE ON [dbo].SUBSTRING_INDEX TO PUBLIC;
-- Tests
DECLARE @TestResults TABLE (i int, answer nVarChar(MAX), expected nVarChar(MAX));
insert into @TestResults
select * from
(
(SELECT 1 as i, [dbo].SUBSTRING_INDEX(N'www.somewebsite.com', N'.', 2) as r, 'www.somewebsite' as e) UNION
(SELECT 2 as i, [dbo].SUBSTRING_INDEX(N'www.yahoo.com', N'.', 2) as r, 'www.yahoo' as e) UNION
(SELECT 3 as i, [dbo].SUBSTRING_INDEX(N'www.outlook.com', N'.', 2) as r, 'www.outlook' as e) UNION
(SELECT 4 as i, [dbo].SUBSTRING_INDEX(N'www.somewebsite.com', N'.', -2) as r, 'somewebsite.com' as e) UNION
(SELECT 5 as i, [dbo].SUBSTRING_INDEX(N'www.yahoo.com', N'.', -2) as r, 'yahoo.com' as e) UNION
(SELECT 6 as i, [dbo].SUBSTRING_INDEX(N'www.outlook.com', N'.', -2) as r, 'outlook.com' as e) UNION
(select 7 as i, [dbo].SUBSTRING_INDEX('hi.you.com','.',2) as r, 'hi.you' as e) UNION
(select 8 as i, [dbo].SUBSTRING_INDEX('hi.you.com','.',-1) as r, 'com' as e) UNION
(select 9 as i, [dbo].SUBSTRING_INDEX(N'prueba','ue',1) as r, 'pr' as e) UNION
(select 10 as i, [dbo].SUBSTRING_INDEX(N'prueba','ue',-1) as r, 'ba' as e) UNION
(select 11 as i, [dbo].SUBSTRING_INDEX(N'prueba','ue',0) as r, '' as e) UNION
(SELECT 12 as i, [dbo].SUBSTRING_INDEX(N'wwwxxxoutlookxxxcom', N'xxx', 2) as r, 'wwwxxxoutlook' as e) UNION
(SELECT 13 as i, [dbo].SUBSTRING_INDEX(N'wwwxxxoutlookxxxcom', N'xxx', -2) as r, 'outlookxxxcom' as e) UNION
(SELECT 14 as i, [dbo].SUBSTRING_INDEX(N'wwwxxxoutlookxxxcom', N'xxx', 5) as r, 'wwwxxxoutlookxxxcom' as e) UNION
(SELECT 15 as i, [dbo].SUBSTRING_INDEX(N'wwwxxxoutlookxxxcom', N'xxx', -5) as r, 'wwwxxxoutlookxxxcom' as e)
) as results;
select tr.i,
tr.answer,
tr.expected,
CASE WHEN tr.answer = tr.expected THEN 'Test Succeeded' ELSE 'Test Failed' END testState
from @TestResults tr
order by i;
CREATE FUNCTION dbo.SUBSTRING_INDEX(@InString NVARCHAR(Max),
@Delimiter NVARCHAR(Max),
@Count INT)
RETURNS NVARCHAR(200)
AS
BEGIN
-- If @Count is zero, we return '' as per spec
IF @Count = 0
BEGIN
RETURN '';
END;
-- First we let the XML parser break up the string by @Delimiter.
-- Each parsed value will be <piece>[text]</piece>.
DECLARE @XmlSourceString XML = (select N'<piece>' + REPLACE( (SELECT @InString AS '*' FOR XML PATH('')) , @Delimiter, N'</piece><piece>' ) + N'</piece>');
-- This will contain the final requested string.
DECLARE @Results nVarChar(MAX);
;WITH Pieces(RowNumber, Piece) as
(
-- Take each node in @XmlSourceString, and return it with row numbers
-- which will identify each piece and give us a handle to change the
-- order, depending on the direction of search.
SELECT row_number() over(order by x.XmlCol) as RowNumber,
@Delimiter + x.XmlCol.value(N'(text())[1]', N'NVARCHAR(MAX)') AS '*'
FROM @XmlSourceString.nodes(N'(piece)') x(XmlCol)
), orderedPieces(RowNumber, Piece) as
(
-- Order the pieces normally or reversed depending on whether they want
-- the first @Count pieces or the last @Count pieces.
select TOP (ABS(@Count))
RowNumber,
Piece
from Pieces
ORDER BY CASE WHEN @Count < 0 THEN RowNumber END DESC ,
CASE WHEN @Count > 0 THEN RowNumber END ASC
), combinedPieces(result) as
(
-- Now combine the pieces back together, ordering them by
-- the original order. There will always
-- be an extra @Delimiter on the front of the string.
select CAST(Piece AS VARCHAR(100))
from OrderedPieces
order by RowNumber
FOR XML PATH(N'')
)
-- Finally, strip off the extra delimiter using STUFF and store the string in @Results.
select @Results = STUFF(result, 1, LEN(@Delimiter), '') from combinedPieces;
return @Results;
END;
此microsoft sql函数的工作原理与mysql中的substring_index函数完全相同
/** This microsoft sql function Works exactly like substring_index function in mysql **/
CREATE FUNCTION SubString_Index
(
@ExistingString NVARCHAR(MAX),
@BreakPoint NVARCHAR(MAX),
@number INT
)
RETURNS NVARCHAR(MAX)
AS
BEGIN
DECLARE @Count INT
DECLARE @SubstringLength INT
DECLARE @Substring NVARCHAR(MAX)
DECLARE @ssubstring NVARCHAR(MAX)
SET @ssubstring=@ExistingString
DECLARE @scount INT
SET @scount=0
DECLARE @sscount INT
SET @sscount=0
DECLARE @number2 INT
DECLARE @occurence INT
SET @occurence=LEN(@ExistingString) - LEN(REPLACE(@ExistingString, @BreakPoint, ''))
If @number<0
BEGIN
SET @number2= @occurence-(-1*@number)+1
END
If @number>0
BEGIN
SET @number2=@number
END
WHILE(@number2>@scount)
BEGIN
Select @Count=CHARINDEX(@BreakPoint,@ExistingString)
Select @SubstringLength=@Count+LEN(@BreakPoint)
Select @ExistingString=SUBSTRING(@ExistingString,@SubstringLength,LEN(@ExistingString)-@Count)
Select @scount=@scount+1
select @sscount=@sscount+@Count
END
If @number<0
BEGIN
if (@number = -1) and (@sscount+LEN(@BreakPoint)) = (LEN(@ssubstring)+1)
BEGIN
SELECT @Substring=''
END
else if @occurence = 0
BEGIN
SELECT @Substring=''
END
else
BEGIN
SELECT @Substring=SUBSTRING(@ssubstring, @sscount+LEN(@BreakPoint), LEN(@ssubstring))
END
END
If @number>0
if @occurence = 0
BEGIN
SELECT @Substring=''
END
else
BEGIN
SELECT @Substring=SUBSTRING(@ssubstring,0,@sscount)
END
RETURN @Substring
END
GO
使用PYTHON获取索引-2
use my_guitar_shop;
go
EXEC sp_execute_external_script
@language =N'Python',
@script=N'
import pandas as pd
import numpy as np
x = np.array(InputDataSet["email_address"], dtype = str)
broken = np.char.split(x, sep = ".")
OutputDataSet = pd.DataFrame([".".join(e[-2:]) if len(e)>2 else ".".join(e) for e in broken])
',
@input_data_1 = N'SELECT email_address from customers;'
WITH RESULT SETS(([indexed_email] nvarchar(250)));
select substring(email,(charindex('@', email,1)+1),100) from yourtable;
祝你好运没有直接的等价项。你需要自己编写。找到了一个implementation。此解决方案不完整，因为它不支持@count为负数，即从字符串的末尾而不是开始搜索。@ScottGartner:使用REVERSE两次。实际上，你必须反转str，但你也需要ave要反转delim虽然您的实现与MySql函数不同，只允许delim是一个字符。如果您运行我的解决方案中的一组测试，您将看到您的函数只通过了15个测试中的5个，其中一个是意外测试编号9恰好有第一个字母匹配，找到了正确的子项string.SELECT reversedbo.SUBSTRING_INDEXreverse'www.mysql.com'，'，2；欢迎使用堆栈溢出！虽然这段代码可能会解决这个问题，但如何以及为什么解决这个问题会真正有助于提高您的文章质量，并可能导致更多的投票。请记住，您是在将来为读者而不是ju回答这个问题现在回答问题的人。请在回答中添加解释，并说明适用的限制和假设。
-- Function to reproduce the useful functionality of SUBSTRING_INDEX from MySql
CREATE FUNCTION dbo.SUBSTRING_INDEX(@InString NVARCHAR(Max),
@Delimiter NVARCHAR(Max),
@Count INT)
RETURNS NVARCHAR(200)
AS
BEGIN
DECLARE @Pos INT;
DECLARE @DelimiterOffsets TABLE
(
i INT IDENTITY(1, 1) NOT NULL,
offset INT NOT NULL
);
-- If @Count is zero, we return '' as per spec
IF @Count = 0
BEGIN
RETURN '';
END;
DECLARE @OrigLength INT = LEN(@InString);
DECLARE @DelimiterLength INT = LEN(@Delimiter);
-- Prime the pump.
SET @Pos = Charindex(@Delimiter, @InString, 1);
-- If the delimiter does not exist in @InString, return the whole string
IF @Pos = 0
BEGIN
RETURN @InString;
END;
-- Put all delimiter offsets into @DelimiterOffsets, they get numbered automatically.
DECLARE @CurrentOffset INT = 0;
WHILE @Pos > 0
BEGIN
SET @CurrentOffset = @Pos;
INSERT INTO @DelimiterOffsets
(offset)
VALUES (@CurrentOffset);
SET @Pos = Charindex(@Delimiter, @InString, @CurrentOffset + @DelimiterLength);
END;
-- This number is guaranteed to be > 0.
DECLARE @DelimitersFound INT = (SELECT Count(*) FROM @DelimiterOffsets);
-- If they requested more delimiters than were found, return the whole string, as per spec.
IF Abs(@Count) > @DelimitersFound
BEGIN
RETURN @InString;
END;
DECLARE @StartSubstring INT = 0;
DECLARE @EndSubstring INT = @OrigLength;
-- OK, now return the part they requested
IF @Count > 0
BEGIN
SET @EndSubstring = (SELECT offset
FROM @DelimiterOffsets
WHERE i = @Count);
END
ELSE
BEGIN
SET @StartSubstring = (SELECT offset + @DelimiterLength
FROM @DelimiterOffsets
WHERE i = (@DelimitersFound + @Count + 1));
END;
RETURN Substring(@InString, @StartSubstring, @EndSubstring);
END;
Go
GRANT EXECUTE ON [dbo].SUBSTRING_INDEX TO PUBLIC;
-- Tests
DECLARE @TestResults TABLE (i int, answer nVarChar(MAX), expected nVarChar(MAX));
insert into @TestResults
select * from
(
(SELECT 1 as i, [dbo].SUBSTRING_INDEX(N'www.somewebsite.com', N'.', 2) as r, 'www.somewebsite' as e) UNION
(SELECT 2 as i, [dbo].SUBSTRING_INDEX(N'www.yahoo.com', N'.', 2) as r, 'www.yahoo' as e) UNION
(SELECT 3 as i, [dbo].SUBSTRING_INDEX(N'www.outlook.com', N'.', 2) as r, 'www.outlook' as e) UNION
(SELECT 4 as i, [dbo].SUBSTRING_INDEX(N'www.somewebsite.com', N'.', -2) as r, 'somewebsite.com' as e) UNION
(SELECT 5 as i, [dbo].SUBSTRING_INDEX(N'www.yahoo.com', N'.', -2) as r, 'yahoo.com' as e) UNION
(SELECT 6 as i, [dbo].SUBSTRING_INDEX(N'www.outlook.com', N'.', -2) as r, 'outlook.com' as e) UNION
(select 7 as i, [dbo].SUBSTRING_INDEX('hi.you.com','.',2) as r, 'hi.you' as e) UNION
(select 8 as i, [dbo].SUBSTRING_INDEX('hi.you.com','.',-1) as r, 'com' as e) UNION
(select 9 as i, [dbo].SUBSTRING_INDEX(N'prueba','ue',1) as r, 'pr' as e) UNION
(select 10 as i, [dbo].SUBSTRING_INDEX(N'prueba','ue',-1) as r, 'ba' as e) UNION
(select 11 as i, [dbo].SUBSTRING_INDEX(N'prueba','ue',0) as r, '' as e) UNION
(SELECT 12 as i, [dbo].SUBSTRING_INDEX(N'wwwxxxoutlookxxxcom', N'xxx', 2) as r, 'wwwxxxoutlook' as e) UNION
(SELECT 13 as i, [dbo].SUBSTRING_INDEX(N'wwwxxxoutlookxxxcom', N'xxx', -2) as r, 'outlookxxxcom' as e) UNION
(SELECT 14 as i, [dbo].SUBSTRING_INDEX(N'wwwxxxoutlookxxxcom', N'xxx', 5) as r, 'wwwxxxoutlookxxxcom' as e) UNION
(SELECT 15 as i, [dbo].SUBSTRING_INDEX(N'wwwxxxoutlookxxxcom', N'xxx', -5) as r, 'wwwxxxoutlookxxxcom' as e)
) as results;
select tr.i,
tr.answer,
tr.expected,
CASE WHEN tr.answer = tr.expected THEN 'Test Succeeded' ELSE 'Test Failed' END testState
from @TestResults tr
order by i;
CREATE FUNCTION dbo.SUBSTRING_INDEX(@InString NVARCHAR(Max),
@Delimiter NVARCHAR(Max),
@Count INT)
RETURNS NVARCHAR(200)
AS
BEGIN
-- If @Count is zero, we return '' as per spec
IF @Count = 0
BEGIN
RETURN '';
END;
-- First we let the XML parser break up the string by @Delimiter.
-- Each parsed value will be <piece>[text]</piece>.
DECLARE @XmlSourceString XML = (select N'<piece>' + REPLACE( (SELECT @InString AS '*' FOR XML PATH('')) , @Delimiter, N'</piece><piece>' ) + N'</piece>');
-- This will contain the final requested string.
DECLARE @Results nVarChar(MAX);
;WITH Pieces(RowNumber, Piece) as
(
-- Take each node in @XmlSourceString, and return it with row numbers
-- which will identify each piece and give us a handle to change the
-- order, depending on the direction of search.
SELECT row_number() over(order by x.XmlCol) as RowNumber,
@Delimiter + x.XmlCol.value(N'(text())[1]', N'NVARCHAR(MAX)') AS '*'
FROM @XmlSourceString.nodes(N'(piece)') x(XmlCol)
), orderedPieces(RowNumber, Piece) as
(
-- Order the pieces normally or reversed depending on whether they want
-- the first @Count pieces or the last @Count pieces.
select TOP (ABS(@Count))
RowNumber,
Piece
from Pieces
ORDER BY CASE WHEN @Count < 0 THEN RowNumber END DESC ,
CASE WHEN @Count > 0 THEN RowNumber END ASC
), combinedPieces(result) as
(
-- Now combine the pieces back together, ordering them by
-- the original order. There will always
-- be an extra @Delimiter on the front of the string.
select CAST(Piece AS VARCHAR(100))
from OrderedPieces
order by RowNumber
FOR XML PATH(N'')
)
-- Finally, strip off the extra delimiter using STUFF and store the string in @Results.
select @Results = STUFF(result, 1, LEN(@Delimiter), '') from combinedPieces;
return @Results;
END;
i answer expected testState
1 www.somewebsite www.somewebsite Test Succeeded
2 www.yahoo www.yahoo Test Succeeded
3 www.outlook www.outlook Test Succeeded
4 somewebsite.com somewebsite.com Test Succeeded
5 yahoo.com yahoo.com Test Succeeded
6 outlook.com outlook.com Test Succeeded
7 hi.you hi.you Test Succeeded
8 com com Test Succeeded
9 pr pr Test Succeeded
10 ba ba Test Succeeded
11 Test Succeeded
12 wwwxxxoutlook wwwxxxoutlook Test Succeeded
13 outlookxxxcom outlookxxxcom Test Succeeded
14 wwwxxxoutlookxxxcom wwwxxxoutlookxxxcom Test Succeeded
15 wwwxxxoutlookxxxcom wwwxxxoutlookxxxcom Test Succeeded
/** This microsoft sql function Works exactly like substring_index function in mysql **/
CREATE FUNCTION SubString_Index
(
@ExistingString NVARCHAR(MAX),
@BreakPoint NVARCHAR(MAX),
@number INT
)
RETURNS NVARCHAR(MAX)
AS
BEGIN
DECLARE @Count INT
DECLARE @SubstringLength INT
DECLARE @Substring NVARCHAR(MAX)
DECLARE @ssubstring NVARCHAR(MAX)
SET @ssubstring=@ExistingString
DECLARE @scount INT
SET @scount=0
DECLARE @sscount INT
SET @sscount=0
DECLARE @number2 INT
DECLARE @occurence INT
SET @occurence=LEN(@ExistingString) - LEN(REPLACE(@ExistingString, @BreakPoint, ''))
If @number<0
BEGIN
SET @number2= @occurence-(-1*@number)+1
END
If @number>0
BEGIN
SET @number2=@number
END
WHILE(@number2>@scount)
BEGIN
Select @Count=CHARINDEX(@BreakPoint,@ExistingString)
Select @SubstringLength=@Count+LEN(@BreakPoint)
Select @ExistingString=SUBSTRING(@ExistingString,@SubstringLength,LEN(@ExistingString)-@Count)
Select @scount=@scount+1
select @sscount=@sscount+@Count
END
If @number<0
BEGIN
if (@number = -1) and (@sscount+LEN(@BreakPoint)) = (LEN(@ssubstring)+1)
BEGIN
SELECT @Substring=''
END
else if @occurence = 0
BEGIN
SELECT @Substring=''
END
else
BEGIN
SELECT @Substring=SUBSTRING(@ssubstring, @sscount+LEN(@BreakPoint), LEN(@ssubstring))
END
END
If @number>0
if @occurence = 0
BEGIN
SELECT @Substring=''
END
else
BEGIN
SELECT @Substring=SUBSTRING(@ssubstring,0,@sscount)
END
RETURN @Substring
END
GO
use my_guitar_shop;
go
EXEC sp_execute_external_script
@language =N'Python',
@script=N'
import pandas as pd
import numpy as np
x = np.array(InputDataSet["email_address"], dtype = str)
broken = np.char.split(x, sep = ".")
OutputDataSet = pd.DataFrame([".".join(e[-2:]) if len(e)>2 else ".".join(e) for e in broken])
',
@input_data_1 = N'SELECT email_address from customers;'
WITH RESULT SETS(([indexed_email] nvarchar(250)));
select substring(email,(charindex('@', email,1)+1),100) from yourtable;