How to achieve the functionality of MySQL's SUBSTRING_INDEX() function in SQL Server?

SQL Server Equivalents of MySQL's SUBSTRING_INDEX Function

MySQL's SUBSTRING_INDEX() function extracts a substring portion before the specified occurrence of a delimiter. To achieve similar functionality in SQL Server, several approaches are available.

T-SQL Scalar Function:

leverages T-SQL and XQuery to break strings into XML rows and extracts rows that match the desired delimiter match.

TSQL Inline Table-Valued Function:

Defines an inline valued table that returns results based on the number of specified delimiter matches, similar to T-SQL Scalar Function but in tabular form.

Usage Example:

T-SQL Scalar Function:

CREATE FUNCTION dbo.SUBSTRING_INDEX
(
    @str NVARCHAR(4000),
    @delim NVARCHAR(1),
    @count INT
)
RETURNS NVARCHAR(4000)
WITH SCHEMABINDING
AS
BEGIN
    /* T-SQL Scalar Function Code */
END;

SELECT dbo.SUBSTRING_INDEX(N'www.somewebsite.com', N'.', 2);

TSQL Inline Table-Valued Function:

CREATE FUNCTION dbo.SUBSTRING_INDEX
(
    @str NVARCHAR(4000),
    @delim NVARCHAR(1),
    @count INT
)
RETURNS TABLE
AS RETURN
    /* TSQL Inline Table-Valued Function Code */

SELECT  *
FROM    (
    SELECT N'www.somewebsite.com' UNION ALL 
    SELECT N'www.yahoo.com' UNION ALL 
    SELECT N'www.outlook.com'
) a(Value)
CROSS APPLY dbo.SUBSTRING_INDEX(a.Value, N'.', 2) b;

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