one method for fetching data and one for sending to db.

fixes #2287

solution used **heukirne** for the names of columns.

fix error occurs when you use multiple databases.

fix error when if fields whose names are reserved word

This alternative solution LIMIT, OFFSET problem SQL Server version older than 2012.

Fixes #3066: `yii\db\mssql\Schema::getTableSchema()` should return null when the table does not exist.

issue #3026

issue #2852

Improved `QueryBuilder::buildLimit()` to support big numbers