String in SQL Server_ Implementation of split function

Summary

SQL Server stay 2016 The version supports STRING_SPLIT Method , String can be divided into delimiters , Cut into a data sheet , Easy to use . however SQL Server 2016 Previous versions did not have this method . This passage SQL Server To implement this method .

Source code and implementation

SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE FUNCTION [dbo].[fn_Split]
(@input nvarchar(max), @separater char(1))
RETURNS 
 @result TABLE (
	value nvarchar(max) not null 
)
AS
BEGIN
	declare @tmp nvarchar (max)
	declare @EndIndex int
	SET @input = @input + @separater
	WHILE LEN(@input) > 0
	BEGIN
		SET @EndIndex = CHARINDEX(@separater, @input)
		SET @tmp =  SUBSTRING(@input, 1, @EndIndex - 1);
		IF LEN(@tmp) > 0
			INSERT INTO @result SELECT  @tmp		
		SET @input = SUBSTRING(@input, @EndIndex+1, LEN(@input)- @EndIndex)
	END
	RETURN 
END
GO

1. Method accepts two parameters , The first is the string to be split , The other is the separator , Separator only 1 position ;
2. Method returns a table valued variable , This variable has only one column value;
3. For the convenience of string processing , Append the delimiter to the end of the string to be split ;
4. Find the position of the first separator in the string to be split , Insert the contents before the delimiter into the table variable , Delete the separator and the string before the separator from the string to be split , Until the string to be split is empty ;
5. Return table variables .

Method call

This method returns a table valued function , So we need to put from After clause

 select * from dbo.fn_Split('a,b,c',',')

This method ignores null values , The following string will only return a b c Three pieces of data .

 select * from dbo.fn_Split('a,b,c,,',',')