1. Built-in functions
2. User Defined functions
There are several built-in functions. In this video session, we will look at the most common string functions available.
ASCII(Character_Expression) - Returns the ASCII code of the given character expression.
To find the ASCII Code of the capital letter 'A'
Example: Select ASCII('A')
Output: 65
CHAR(Integer_Expression) - Converts an int ASCII code to a character. The Integer_Expression should be between 0 and 255.
The following SQL, prints all the characters for the ASCII values from o thru 255
Declare @Number int
Set @Number = 1
While(@Number <= 255)
Begin
Print CHAR(@Number)
Set @Number = @Number + 1
End
Note: The while loop will become an infinite loop if you forget to include the following line.
Set @Number = @Number + 1
Printing uppercase alphabets using CHAR() function:
Declare @Number int
Set @Number = 65
While(@Number <= 90)
Begin
Print CHAR(@Number)
Set @Number = @Number + 1
End
Printing lowercase alphabets using CHAR() function:
Declare @Number int
Set @Number = 97
While(@Number <= 122)
Begin
Print CHAR(@Number)
Set @Number = @Number + 1
End
Another way of printing lower case alphabets using CHAR() and LOWER() functions.
Declare @Number int
Set @Number = 65
While(@Number <= 90)
Begin
Print LOWER(CHAR(@Number))
Set @Number = @Number + 1
End
LTRIM(Character_Expression) - Removes blanks on the left-hand side of the given character expression.
Example: Removing the 3 white spaces on the left-hand side of the ' Hello' string using the LTRIM() function.
Select LTRIM(' Hello')
Output: Hello
RTRIM(Character_Expression) - Removes blanks on the right-hand side of the given character expression.
Example: Removing the 3 white spaces on the left-hand side of the 'Hello ' string using RTRIM() function.
Select RTRIM('Hello ')
Output: Hello
Example: To remove white spaces on either side of the given character expression, use LTRIM() and RTRIM() as shown below.
Select LTRIM(RTRIM(' Hello '))
Output: Hello
LOWER(Character_Expression) - Converts all the characters in the given Character_Expression, to lowercase letters.
Example: Select LOWER('CONVERT This String Into Lower Case')
Output: convert this string into lower case
UPPER(Character_Expression) - Converts all the characters in the given Character_Expression, to uppercase letters.
Example: Select UPPER('CONVERT This String Into upper Case')
Output: CONVERT THIS STRING INTO UPPER CASE
REVERSE('Any_String_Expression') - Reverses all the characters in the given string expression.
Example: Select REVERSE('ABCDEFGHIJKLMNOPQRSTUVWXYZ')
Output: ZYXWVUTSRQPONMLKJIHGFEDCBA
LEN(String_Expression) - Returns the count of total characters, in the given string expression, excluding the blanks at the end of the expression.
Example: Select LEN('SQL Functions ')
Output: 13
In the next session, we will discuss the rest of the commonly used built-in string functions