SQL Reverse String Words

In this article we will show you, How to write a SQL Query to reverse each and every word present in a string with example. This is one of the common SQL Interview Question you might face in the interviews.

SQL Reverse String Word by Word Example

The SQL SUBSTRING Function allows you to extract and display the part of a string. In this example we will show you, How to Select string before the space symbol.

-- SQL Extract Domain From Email

DECLARE @Source VARCHAR(MAX)
DECLARE @Destination VARCHAR(MAX)
DECLARE @Length INT 

SET @Source = 'Welcome to SQL Server Tutorial Service at Tutorial Gateway'
SET @Destination = ''

WHILE LEN(@Source) > 0
  BEGIN
    IF CHARINDEX(' ', @Source) > 0
    BEGIN
	SET @Destination = SUBSTRING(@Source, 0, CHARINDEX(' ', @Source)) + ' ' + @Destination
	SET @Source = LTRIM(RTRIM(SUBSTRING(@Source, CHARINDEX(' ', @Source) + 1, LEN(@Source))))
    END
    ELSE
    BEGIN
	SET @Destination = @Source + ' ' + @Destination
	SET @Source = ''
    END
  END

SELECT @Destination

OUTPUT: Let me show you the output of the statement

ANALYSIS
First we declared three variables using the DECLARE statement. Next we used the WHILE Loop to iterate each and every character present in the @Source. For the condition inside the while loop, we used the SQL LEN Function to check whether the length of the source is greater than 0 or not.

Within the while loop, we used the SQL SUBSTRING Function to set the @Destination value. And it allows three parameters and they are: Source, start point, end point. Here we assigned the

Source as @Source or you can use Column Name
Next, we used the starting position as 0.
Next, we used the SQL CHARINDEX Function to find the ‘ ‘. so that the end point will be before the space.
Lastly, we are adding this to @Destination, and it is empty at the starting of the loop

To set the @Source value (it means update the @source variable) we are using the SQL SUBSTRING Function. Here we assigned the

Source as @Source or you can use Column Name
Next, we used the SQL CHARINDEX Function to find the empty space, and then we added 1. so that the starting point will be after the empty space.
Lastly, we used the SQL LEN Function to specify the end value

From the above analysis you can observe that,

SET @Destination means we are extracting the word starting at 0 index and up to empty space. That will be the first word.
Once we got our first word, we will remove that word from @Source using the SET @Source code.

SQL Reverse String Word by Word Example 2

Although the above example will return the result, we just want to wrap it in the User Defined Function. I suggest you to refer User Defined Function article for better understanding.

-- SQL String Reverse Example - Reverse String words

USE [SQLTEST]
GO
CREATE FUNCTION [ReverseStringWords]
(
    @Source VARCHAR(MAX)
)
RETURNS VARCHAR(MAX)  
BEGIN
         
   DECLARE @Destination VARCHAR(MAX)
   SET @Destination = '' 
    
   DECLARE @Length INT
     
   WHILE LEN(@Source) > 0
   BEGIN
      IF CHARINDEX(' ', @Source) > 0
      BEGIN
         SET @Destination = SUBSTRING(@Source, 0, CHARINDEX(' ', @Source)) + ' ' + @Destination
         SET @Source = LTRIM(RTRIM(SUBSTRING(@Source, CHARINDEX(' ', @Source) + 1, LEN(@Source))))
      END
      ELSE
      BEGIN
         SET @Destination = @Source + ' ' + @Destination
         SET @Source = ''
      END
   END          
   RETURN @Destination
END

OUTPUT
We can find the user defined function in two ways. Please navigate to the Database that contains the function -> Programmability -> Scalar-valued Functions -> function name. Next, right click on the function will open the context menu. Here, please select the option as we shown below.

Or you can simply write the following SQL code snippet

-- SQL Server String Reverse Example
USE [SQLTEST]
GO

SELECT [dbo].[ReverseStringWords]('Welcome To SQL Server Tutorial Service at Tutorial Gateway')
GO

And the Output is

OUTPUT

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