There is sometimes a need to figure out the maximum space that is being used by a particular column in your database. You would initially think that the LEN() function would allow you to do this, but this function does not work on Text, NText or Image data types, so how do you figure out the length of a value in a column that has one of these data types?
SolutionIn addition to the LEN() function, SQL Server also has a DATALENGTH() function. This function can be used on all data types in your table.
Here is an example of running these commands on an IMAGE data type using the LEN function:
SELECT name, LEN(packagedata)
FROM dbo.sysdtspackages
query results
Here is an example of running these commands on an IMAGE data type using the DATALENGTH function:
SELECT name, DATALENGTH(packagedata)
FROM dbo.sysdtspackages
query results
If you wanted to find out the maximum length used for all of your records you could issue a command such as the following:
SELECT TOP 1 name, DATALENGTH(packagedata)
FROM dbo.sysdtspackages
ORDER BY 2 DESC
That is all there is to it. Another little function that you probably won't use often, but this is helpful to know it is there when you do need to use it.
