In SQL Server, you can use the LEN() function to return the number of characters in a string. This is a Transact-SQL function that can also be used in Azure databases.

In MySQL, you need to use the CHAR_LENGTH() function.

Examples

Here’s an example of each.

SQL Server (T-SQL)

SELECT LEN('Cat') AS 'T-SQL';

Result:

T-SQL
-----
3    

MySQL

SELECT CHAR_LENGTH('Cat') AS MySQL;

Result:

+-------+
| MySQL |
+-------+
|     3 |
+-------+

Watch Out for Trailing Blanks!

One difference between these functions is in the way they treat trailing blanks (e.g. spaces at the end of the string). T-SQL’s LEN() function excludes trailing blanks, while MySQL’s CHAR_LENGTH() function includes them.

So if we add trailing blanks to the previous examples, we get the following.

SQL Server (T-SQL)

SELECT LEN('Cat ') AS 'T-SQL';

Result:

T-SQL
-----
3    

MySQL

SELECT CHAR_LENGTH('Cat ') AS MySQL;

Result:

+-------+
| MySQL |
+-------+
|     4 |
+-------+

If you need to exclude trailing blanks in MySQL, you’ll need to wrap the string in a TRIM() function. Like this:

SELECT CHAR_LENGTH(TRIM('Cat ')) AS 'MySQL with TRIM';

Result:

+-----------------+
| MySQL with TRIM |
+-----------------+
|               3 |
+-----------------+

But Don’t Worry about Leading Blanks!

Both T-SQL’s LEN() function and MySQL’s CHAR_LENGTH() function include leading blanks.

SQL Server (T-SQL)

SELECT LEN(' Cat') AS 'T-SQL';

Result:

T-SQL
-----
4     

MySQL

SELECT CHAR_LENGTH(' Cat') AS 'MySQL';

Result:

+-------+
| MySQL |
+-------+
|     4 |
+-------+