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Friday, June 20, 2014

Easy Way to remove HTML tags in SQL Server

We were looking for a way to remove/strip HTML tags from varchar columns. On making search found some code samples, which suggested to create a stored procedure like following.

Click to view Stored Procedure StripHtml

CREATE FUNCTION [dbo].[StripHtml] (@HTMLText VARCHAR (MAX))
RETURNS VARCHAR (MAX)
AS
BEGIN
DECLARE @Start  int
DECLARE @End    int
DECLARE @Length int

-- Replace the HTML entity & with the '&' character (this needs to be done first, as
-- '&' might be double encoded as '&')
SET @Start = CHARINDEX ('&', @HTMLText)
SET @End = @Start + 4
SET @Length = (@End - @Start) + 1

WHILE (@Start > 0 AND @End > 0 AND @Length > 0) BEGIN
SET @HTMLText = STUFF (@HTMLText, @Start, @Length, '&')
SET @Start = CHARINDEX ('&', @HTMLText)
SET @End = @Start + 4
SET @Length = (@End - @Start) + 1
END

-- Replace the HTML entity < with the '<' character
SET @Start = CHARINDEX ('<', @HTMLText)
SET @End = @Start + 3
SET @Length = (@End - @Start) + 1

WHILE (@Start > 0 AND @End > 0 AND @Length > 0) BEGIN
SET @HTMLText = STUFF (@HTMLText, @Start, @Length, '<')
SET @Start = CHARINDEX ('<', @HTMLText)
SET @End = @Start + 3
SET @Length = (@End - @Start) + 1
END

-- Replace the HTML entity > with the '>' character
SET @Start = CHARINDEX ('>', @HTMLText)
SET @End = @Start + 3
SET @Length = (@End - @Start) + 1

WHILE (@Start > 0 AND @End > 0 AND @Length > 0) BEGIN
SET @HTMLText = STUFF (@HTMLText, @Start, @Length, '>')
SET @Start = CHARINDEX ('>', @HTMLText)
SET @End = @Start + 3
SET @Length = (@End - @Start) + 1
END

-- Replace the HTML entity & with the '&' character
SET @Start = CHARINDEX ('&amp;', @HTMLText)
SET @End = @Start + 4
SET @Length = (@End - @Start) + 1

WHILE (@Start > 0 AND @End > 0 AND @Length > 0) BEGIN
SET @HTMLText = STUFF (@HTMLText, @Start, @Length, '&')
SET @Start = CHARINDEX ('&amp;', @HTMLText)
SET @End = @Start + 4
SET @Length = (@End - @Start) + 1
END

-- Replace the HTML entity   with the ' ' character
SET @Start = CHARINDEX (' ', @HTMLText)
SET @End = @Start + 5
SET @Length = (@End - @Start) + 1

WHILE (@Start > 0 AND @End > 0 AND @Length > 0) BEGIN
SET @HTMLText = STUFF (@HTMLText, @Start, @Length, ' ')
SET @Start = CHARINDEX (' ', @HTMLText)
SET @End = @Start + 5
SET @Length = (@End - @Start) + 1
END

-- Replace any
tags with a newline
SET @Start = CHARINDEX ('<br />', @HTMLText)
SET @End = @Start + 3
SET @Length = (@End - @Start) + 1

WHILE (@Start > 0 AND @End > 0 AND @Length > 0) BEGIN
SET @HTMLText = STUFF (@HTMLText, @Start, @Length, CHAR(13) + CHAR(10))
SET @Start = CHARINDEX ('<br />', @HTMLText)
SET @End = @Start + 3
SET @Length = (@End - @Start) + 1
END

-- Replace any
tags with a newline
SET @Start = CHARINDEX ('<br />', @HTMLText)
SET @End = @Start + 4
SET @Length = (@End - @Start) + 1

WHILE (@Start > 0 AND @End > 0 AND @Length > 0) BEGIN
SET @HTMLText = STUFF (@HTMLText, @Start, @Length, 'CHAR(13) + CHAR(10)')
SET @Start = CHARINDEX ('<br />', @HTMLText)
SET @End = @Start + 4
SET @Length = (@End - @Start) + 1
END

-- Replace any
tags with a newline
SET @Start = CHARINDEX ('<br />', @HTMLText)
SET @End = @Start + 5
SET @Length = (@End - @Start) + 1

WHILE (@Start > 0 AND @End > 0 AND @Length > 0) BEGIN
SET @HTMLText = STUFF (@HTMLText, @Start, @Length, 'CHAR(13) + CHAR(10)')
SET @Start = CHARINDEX ('<br />', @HTMLText)
SET @End = @Start + 5
SET @Length = (@End - @Start) + 1
END

-- Remove anything between tags
SET @Start = CHARINDEX ('<', @HTMLText)
SET @End = CHARINDEX ('>', @HTMLText, CHARINDEX ('<', @HTMLText))
SET @Length = (@End - @Start) + 1

WHILE (@Start > 0 AND @End > 0 AND @Length > 0) BEGIN
SET @HTMLText = STUFF (@HTMLText, @Start, @Length, '')
SET @Start = CHARINDEX ('<', @HTMLText)
SET @End = CHARINDEX ('>', @HTMLText, CHARINDEX ('<', @HTMLText))
SET @Length = (@End - @Start) + 1
END

RETURN LTRIM( RTRIM(@HTMLText))

END

GO



This stored procedure does what it says, but it is lot of code and procedural. So, thought of using XML data type and value method of SQL Server as embedded below.










NB: HTML text must be properly formatted otherwise we will get XML Parsing error.

Hope it Helps.
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