SQL Length Function

The LENGTH() and CHARACTER_LENGTH() functions in SQL are essentially equivalent; both functions return the number of characters in a string. The key difference lies in how they handle multi-byte characters: LENGTH() returns the number of bytes, while CHARACTER_LENGTH() returns the number of characters, making it more appropriate for multi-byte (Unicode) strings. However, please note that their precise behavior can vary somewhat between different SQL dialects, so always consult the documentation for your specific SQL platform.
Here is an example of how to combine the LENGTH() and CHARACTER_LENGTH() functions in a single SQL query:

SELECT 
    customer_name,
    LENGTH(customer_name) AS ByteLength,
    CHARACTER_LENGTH(customer_name) AS CharLength
FROM
    customers;

In this query, customer_name is a column from the customers table. The query will return a list of customers' names along with the byte length and character length of each name.
Remember, if you're working with a SQL dialect that doesn't support CHARACTER_LENGTH(), you might use LENGTH() instead, although be aware of the aforementioned limitation concerning multi-byte characters.

The length of a string is important to know when lining up columns, formatting information, and generally working with strings. The function returns a number representing the overall length of the string. This function is supported differently in different engines. You may see it as LEN or LENGTH. You will need to check with your server's documentation to see which implementation is used. In fact, some database engines do not support this function at all. For example, Microsoft's SQL Server expects that you will determine the length on the client-side of the query, not on the server-side. If your engine does support LEN or LENGTH, the syntax is as follows:

SELECT LEN(MyColumn) 
FROM MyTable

or

SELECT LENGTH(MyColumn) 
FROM MyTable

In either case, you are provided with the length of the values in the MyColumn column, in a derived, unnamed column.

Use the function CHARACTER_LENGTH() to return the number of characters in a string. The function's important characteristics are:

1. CHARACTER_LENGTH() returns an integer greater than or equal to zero.
2. CHARACTER_LENGTH() counts characters, not bytes. A multibyte or Unicode character represents one character.
3. The length of an empty string (' ' ) is zero.
4. If its argument is null, CHARACTER_LENGTH() returns null.

Type:

CHARACTER_LENGTH(string)

string is a string expression such as a column that contains character strings, a string literal, or the result of an operation or function that returns a string (Listings 4.51 and 4.52)

SELECT au_fname,
  CHARACTER_LENGTH(au_fname) AS "Len"
FROM authors;

au_fname	Len
Sarah	5
Wendy	5
Hallie	6
Klee	4
Christian	9
	0
Paddy	5

Listing 4.51 List the lengths of the authors' first names.

---

Example 4.52

title_name	Len
1977!	5
Kiss My Boo-Boo	15
How About Never?	16
I Blame My Mother	17
Exchange of Platitudes	22
200 Years of German Humor	25
Spontaneous, Not Annoying	25
But I Did It Unconsciously	26
Not Without My Faberge Egg	26
Just Wait Until After School	28
Ask Your System Administrator	29

Sql Function - Exercise