SQL ASCII Function

The SQL ASCII function is used to return the ASCII code of the leftmost character of a character expression. The syntax of the SQL Server ASCII Function is

SELECT ASCII (Character_Expression)
FROM [Source]

Character_Expression: Please specify the valid Expression for which you want to find the ASCII code. The SQL ASCII Function will return the ASCII code of the leftmost character of this expression. This Character_Expression can be a Char or Varchar. This String ASCII function will return INT

SQL ASCII Function Example 1

The SQL Server ASCII Function returns the ASCII code of the leftmost character of the given expression. The following query will show multiple ways to use this ASCII function.

TIP: Please refer ASCII Table to check the character codes of each character.


-- Initialize the variables.  
SET @i = 'a'
SET @j = 1

SELECT ASCII(@i) AS Result1,
	ASCII(@j) AS Result2 ;

SELECT ASCII('efgh') AS Result3;  

SELECT ASCII('789') AS Result4;
SQL ASCII Function 1

We are finding the ASCII code of alphabet ‘a’ and integer 1. We also assigned new names to the result as ‘Result1’, and ‘Result2’ using ALIAS Column in SQL Server.

SELECT ASCII(@i) AS Result1,
       ASCII(@j) AS Result2 ;

In the next line, We used the SQL ASCII function directly on a group of characters (word). Here, ASCII function will return leftmost character (i.e., e) and that should be 101

SELECT ASCII('efgh') AS Result3;

Next, we used the ASCII function directly on integer. Here, ASCII String Functions will return leftmost character (i.e., 7) and that should be 55

SELECT ASCII('789') AS Result4;

ASCII Function Example 2

In this example, We are going to use the SQL ASCII function inside the WHILE LOOP. I suggest you refer both the SUBSTRING and WHILE LOOP articles.

DECLARE @i int, 
        @str char(16);  

-- Initialize the variables.  
SET @i = 1;  
SET @str = 'Tutorial Gateway'; 
		SELECT SUBSTRING(@str, @i, 1) AS [Char_Value],
			ASCII(SUBSTRING(@str, @i, 1)) AS [ASCII_Result]
		SET @i = @i + 1
SQL ASCII Function 2

ASCII Function Example 3

In this example, we are going to implement the SQL Server ASCII function on the column. For this, We use the below-shown data

SQL ASCII Function 4

The following statement will return the ASCII code of leftmost character in [FirstName] column and [LastName] column and ASCII code of leftmost number in [YearlyIncome] column.

SELECT [FirstName] 
      ,ASCII([FirstName]) AS [FN_ASCII] 
      ,ASCII([LastName]) AS [LN_ASCII] 
      ,ASCII([YearlyIncome]) AS [YI_ASCII]
  FROM [SQL Tutorial].[dbo].[Employee]

As you can see, 74 is the ASCII code of J, 89 is the ASCII code for Y, and 57 is the ASCII code for 9

SQL ASCII Function 3