Take a look at the OFFSET and FETCHFIRST keywords as documented on page 13 of: https://fmhelp.filemaker.com/docs/13/en/fm13_sql_reference.pdf
This is a reference document that you can find and open if you select "more documentation" from the Product Documentation sub menu found in FileMaker's help menu.
another method is to simply enclose the ExecuteSQL function inside a Leftvalues funciton:
LeftValues ( Execute SQL ( SQLQueryGoesHere ) ; 20 )
thnax! i used the seconf option, that was very easy :)