If you're looking for a way to do it directly through the msi, then to launch your SQL script, you'll have to create a custom action to call one of the various sql executables (osql.exe, sql.exe, sqlplus.exe, or Svrmgrl.exe) and pass it your script file as a parameter.
If you're looking for an installscript based solution, then you can find an example of this on installsite.org under the heading "SQL Server Database Maintenance" at the following link:
http://www.installsite.org/pages/en/isp_db.htmHope this helps.
Mark D
Software Quality Engineer
InstallShield Software Corp.