This conversion is needed by users that try to load their MySQL Workbench databases (.nwb) to SQL format. MWB is proprietary format, which also holds information of the graphical representation in Workbench, whilst .sql file is a script used by MySQL to interpret the database.
You will basically need a script that transforms one to another. One way would be through command line (mysql -u yourUser -p yourDatabase < yourFile.sql), the other way resolves around decompressing your .nwb file and translating the XML script inside to .sql. Both ways kinda require that you know what you are doing.
When in doubt, consult Stack Overflow for more help. Always plenty of people there that know their stuff.