sql - TSQL - How to URL Encode

Sql - TSQL - How to URL Encode

In T-SQL, there is no built-in function to URL encode a string. However, you can create a custom function to perform URL encoding by replacing special characters with their percent-encoded equivalents.

Here's how you can create a user-defined function to URL encode a string in T-SQL:

Step-by-Step Guide

  1. Create a Function to URL Encode Characters
  2. Use the Function in Your Queries

1. Create a Function to URL Encode Characters

This function iterates over each character in the input string and replaces it with its percent-encoded equivalent if it is a special character.

CREATE FUNCTION dbo.UrlEncode(@input NVARCHAR(MAX)) RETURNS NVARCHAR(MAX) AS BEGIN DECLARE @output NVARCHAR(MAX) = '' DECLARE @i INT = 1 DECLARE @c NCHAR(1) DECLARE @hex NCHAR(2) WHILE @i <= LEN(@input) BEGIN SET @c = SUBSTRING(@input, @i, 1) IF @c LIKE '[A-Za-z0-9-_.~]' BEGIN SET @output = @output + @c END ELSE BEGIN SET @hex = SUBSTRING('0123456789ABCDEF', (UNICODE(@c) / 16) + 1, 1) + SUBSTRING('0123456789ABCDEF', (UNICODE(@c) % 16) + 1, 1) SET @output = @output + '%' + @hex END SET @i = @i + 1 END RETURN @output END GO

2. Use the Function in Your Queries

You can use this function in your SQL queries to URL encode any string.

Example Usage

SELECT dbo.UrlEncode('Hello, World!') AS EncodedString;

This will produce the following output:

EncodedString
Hello%2C%20World%21

Explanation

  • Initialization:

    • @output is the string that will store the result.
    • @i is the index to iterate through the input string.
    • @c is the current character being processed.
    • @hex is used to store the hexadecimal representation of the character.

  • Loop Through Each Character:

    • The WHILE loop iterates over each character in the input string.
    • SUBSTRING(@input, @i, 1) gets the character at position @i.

  • Check if Character is Alphanumeric or Safe:

    • If the character is a letter, number, or one of the safe characters (-_.~), it is appended directly to the output.
    • Otherwise, it is converted to its percent-encoded form.

  • Convert Character to Percent-Encoding:

    • UNICODE(@c) gets the Unicode value of the character.
    • The Unicode value is divided by 16 to get the first hex digit and the remainder gives the second hex digit.
    • SUBSTRING('0123456789ABCDEF', ...) retrieves the corresponding hex digit.

  • Return the Result:

    • The encoded string is returned after all characters have been processed.

Notes

  • This function handles basic URL encoding. If you need to handle other special cases or characters, you might need to extend the function.
  • For large input strings, performance might need to be optimized further, possibly using more advanced techniques or stored procedures.

This approach provides a way to perform URL encoding directly within T-SQL, which can be useful for preparing data for web-based applications or APIs.

Examples

  1. SQL Server URL Encode with built-in functions

    • Description: Encode a string to URL format using built-in functions in SQL Server (T-SQL).
    DECLARE @inputString NVARCHAR(MAX) = 'Hello World!'; DECLARE @encodedString NVARCHAR(MAX); SET @encodedString = REPLACE(REPLACE(REPLACE(REPLACE(REPLACE( REPLACE(REPLACE(REPLACE(REPLACE(REPLACE( @inputString, ' ', '%20'), '!', '%21'), '#', '%23'), '$', '%24'), '&', '%26'), '\'', '%27'), '(', '%28'), ')', '%29'), '*', '%2A'), '+', '%2B'); SELECT @encodedString AS EncodedString;

    This example manually replaces specific characters (' ', '!', '#', '$', '&', '\'', '(', ')', '*', '+') with their URL encoded equivalents using REPLACE() function in SQL Server.

  2. SQL Server URL Encode with CLR function

    • Description: Use a CLR (Common Language Runtime) function to perform URL encoding in SQL Server (T-SQL).
    CREATE ASSEMBLY CLRUtilities AUTHORIZATION dbo FROM 'C:\Path\To\Your\CLRUtilities.dll' WITH PERMISSION_SET = SAFE; CREATE FUNCTION dbo.URL_Encode(@inputString NVARCHAR(MAX)) RETURNS NVARCHAR(MAX) EXTERNAL NAME CLRUtilities.UserDefinedFunctions.URL_Encode;

    This code snippet demonstrates creating a CLR function (URL_Encode) in SQL Server by referencing a CLR assembly (CLRUtilities.dll) that contains the implementation for URL encoding.

  3. SQL Server URL Encode using CHARINDEX and PATINDEX

    • Description: Encode a string to URL format using CHARINDEX and PATINDEX functions in SQL Server (T-SQL).
    DECLARE @inputString NVARCHAR(MAX) = 'Hello World!'; DECLARE @encodedString NVARCHAR(MAX) = ''; WHILE LEN(@inputString) > 0 BEGIN DECLARE @char NVARCHAR(1); SET @char = LEFT(@inputString, 1); SET @inputString = SUBSTRING(@inputString, 2, LEN(@inputString) - 1); IF PATINDEX('[A-Za-z0-9]', @char) = 0 SET @encodedString = @encodedString + '%' + RIGHT('00' + CAST(ASCII(@char) AS VARCHAR), 2); ELSE SET @encodedString = @encodedString + @char; END SELECT @encodedString AS EncodedString;

    This script iterates through each character in @inputString, checking if it's alphanumeric or needs encoding (%xx format) based on its ASCII value.

  4. SQL Server URL Encode using XML Path trick

    • Description: Encode a string to URL format using XML Path trick in SQL Server (T-SQL).
    DECLARE @inputString NVARCHAR(MAX) = 'Hello World!'; DECLARE @encodedString NVARCHAR(MAX); SELECT @encodedString = ( SELECT CASE WHEN UNICODE(char) < 128 THEN char ELSE '%' + SUBSTRING(master.dbo.fn_varbintohexstr(CAST(UNICODE(char) AS VARBINARY)), 3, 2) END AS [text()] FROM (SELECT SUBSTRING(@inputString, number, 1) AS char FROM master.dbo.spt_values WHERE type = 'P' AND number BETWEEN 1 AND LEN(@inputString)) AS characters FOR XML PATH('') ); SELECT @encodedString AS EncodedString;

    This query utilizes the XML Path method to iterate through each character in @inputString, encoding non-ASCII characters using their hexadecimal representation.

  5. SQL Server URL Encode with REPLICATE and STUFF

    • Description: Encode a string to URL format using REPLICATE and STUFF functions in SQL Server (T-SQL).
    DECLARE @inputString NVARCHAR(MAX) = 'Hello World!'; DECLARE @encodedString NVARCHAR(MAX) = ''; SELECT @encodedString = STUFF(( SELECT CASE WHEN UNICODE(char) < 128 THEN char ELSE '%' + REPLICATE('0', 2 - LEN(CONVERT(VARCHAR, UNICODE(char), 16))) + CONVERT(VARCHAR, UNICODE(char), 16) END FROM (SELECT SUBSTRING(@inputString, number, 1) AS char FROM master.dbo.spt_values WHERE type = 'P' AND number BETWEEN 1 AND LEN(@inputString)) AS characters FOR XML PATH('') ), 1, 0, ''); SELECT @encodedString AS EncodedString;

    This code snippet uses STUFF and REPLICATE functions to iterate through each character in @inputString, encoding non-ASCII characters into URL format.

  6. SQL Server URL Encode with custom function

    • Description: Define and use a custom T-SQL function for URL encoding in SQL Server.
    CREATE FUNCTION dbo.URL_Encode(@inputString NVARCHAR(MAX)) RETURNS NVARCHAR(MAX) AS BEGIN DECLARE @encodedString NVARCHAR(MAX) = ''; SELECT @encodedString = @encodedString + CASE WHEN UNICODE(char) < 128 THEN char ELSE '%' + SUBSTRING(master.dbo.fn_varbintohexstr(CAST(UNICODE(char) AS VARBINARY)), 3, 2) END FROM (SELECT SUBSTRING(@inputString, number, 1) AS char FROM master.dbo.spt_values WHERE type = 'P' AND number BETWEEN 1 AND LEN(@inputString)) AS characters; RETURN @encodedString; END;

    This script creates a user-defined function (dbo.URL_Encode) that encodes a string to URL format using a similar approach with UNICODE, master.dbo.fn_varbintohexstr, and SUBSTRING.

  7. SQL Server URL Encode using WHILE loop

    • Description: Encode a string to URL format using a WHILE loop in SQL Server (T-SQL).
    DECLARE @inputString NVARCHAR(MAX) = 'Hello World!'; DECLARE @encodedString NVARCHAR(MAX) = ''; DECLARE @i INT = 1; WHILE @i <= LEN(@inputString) BEGIN DECLARE @char NVARCHAR(1) = SUBSTRING(@inputString, @i, 1); SET @encodedString = @encodedString + CASE WHEN UNICODE(@char) < 128 THEN @char ELSE '%' + RIGHT('0' + CONVERT(VARCHAR, UNICODE(@char), 16), 2) END; SET @i = @i + 1; END SELECT @encodedString AS EncodedString;

    This query utilizes a WHILE loop to iterate through each character in @inputString, encoding non-ASCII characters into URL format.

  8. SQL Server URL Encode with PATINDEX and SUBSTRING

    • Description: Encode a string to URL format using PATINDEX and SUBSTRING functions in SQL Server (T-SQL).
    DECLARE @inputString NVARCHAR(MAX) = 'Hello World!'; DECLARE @encodedString NVARCHAR(MAX) = ''; DECLARE @i INT = 1; WHILE @i <= LEN(@inputString) BEGIN DECLARE @char NVARCHAR(1) = SUBSTRING(@inputString, @i, 1); SET @encodedString = @encodedString + CASE WHEN PATINDEX('[A-Za-z0-9]', @char) > 0 THEN @char ELSE '%' + RIGHT('0' + CONVERT(VARCHAR, UNICODE(@char), 16), 2) END; SET @i = @i + 1; END SELECT @encodedString AS EncodedString;

    This script uses PATINDEX to check if the character is alphanumeric and encodes non-alphanumeric characters into URL format accordingly.

  9. SQL Server URL Encode with recursive CTE

    • Description: Encode a string to URL format using a recursive Common Table Expression (CTE) in SQL Server (T-SQL).
    DECLARE @inputString NVARCHAR(MAX) = 'Hello World!'; DECLARE @encodedString NVARCHAR(MAX); WITH EncodeCTE AS ( SELECT 1 AS pos, SUBSTRING(@inputString, 1, 1) AS char UNION ALL SELECT pos + 1, SUBSTRING(@inputString, pos + 1, 1) FROM EncodeCTE WHERE pos < LEN(@inputString) ) SELECT @encodedString = COALESCE(@encodedString + CASE WHEN UNICODE(char) < 128 THEN char ELSE '%' + RIGHT('0' + CONVERT(VARCHAR, UNICODE(char), 16), 2) END, '') FROM EncodeCTE; SELECT @encodedString AS EncodedString;

    This example uses a recursive CTE (EncodeCTE) to iterate through each character in @inputString, encoding non-ASCII characters into URL format.

More Tags

multilinestring angular2-observables ag-grid sim800 self-signed substring combinations numeric-input eloquent file-access

More Programming Questions

More Housing Building Calculators

More Various Measurements Units Calculators

More Entertainment Anecdotes Calculators

More Transportation Calculators