How to Efficiently Parse Comma-Separated Strings for SQL IN Lists?
Jan 09, 2025 pm 02:21 PM
Parse comma separated string into IN list in SQL WHERE clause
Assume that the stored procedure receives a comma-separated string parameter that represents multiple values, such as username or account number. In order to filter rows based on these values, we need to construct an IN list in the WHERE clause.
The recommended approach in SQL Server 2005 and above is to use table-valued functions, for example:
CREATE FUNCTION [dbo].[f_split](
@param NVARCHAR(MAX),
@delimiter CHAR(1)
)
RETURNS @t TABLE (
val NVARCHAR(MAX),
seq INT
)
AS
BEGIN
SET @param += @delimiter;
WITH a AS (
SELECT CAST(1 AS BIGINT) AS f, CHARINDEX(@delimiter, @param) AS t, 1 AS seq
UNION ALL
SELECT t + 1, CHARINDEX(@delimiter, @param, t + 1), seq + 1
FROM a
WHERE CHARINDEX(@delimiter, @param, t + 1) > 0
)
INSERT @t
SELECT SUBSTRING(@param, f, t - f), seq FROM a
OPTION (MAXRECURSION 0);
RETURN;
END;
To use this function to parse a string into a list of INs, construct a subquery:
SELECT * FROM yourtable WHERE account IN (SELECT val FROM dbo.f_split(@account, ','))
Alternatively, you can use a simple but less efficient method of pattern matching using the LIKE operator:
WHERE account LIKE '%,' + @account + '%,
In contrast, utilizing the f_split function can provide better performance, especially when dealing with large data sets.
The above is the detailed content of How to Efficiently Parse Comma-Separated Strings for SQL IN Lists?. For more information, please follow other related articles on the PHP Chinese website!
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