why when I importing database the file format must zip why dont sql??
There are strict size limits on .sql database uploads so best to zip it firstly to compress the size.
If your file still exceeds the SQL limit then you are better off trying www.ozerov.de/bigdump/
There are SQL file upload size limits as well as a PHP timeout which means if the database you try to import is large it may time-out, BigDump usually works around this.