"How can we import tables from SQL database into Essbase Cube".
We dont import tables into Essbase, we define mapping from the source tables columns with the dimensions in outline using Rules files.
Within Rules file you can define complex SQL queries and can do handful tranformations for data coulmns.
Once you have defined the rule, you can reuse it.
Note that you need to define an ODBC for your SQL database on Essbase server.
You can also think of Essbase studio to import SQL tables and define mapping and load to Essbase cubes as well.