This reverts commit ea10ba49.

$column->enumValues is set to array[0 =>''] even if $info['enum_values'] is null.
Gii generates always dropDownList in forms.

issue #3520

fixes #3578

This is a porting from yii framework version 1.
I need it to run functional tests with fixtures.

issue #3494

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

Revert "Fixes #3469: Fixed the bug that `QueryBuilder::getColumnType()` may drop the provided column precision in certain cases"

This reverts commit a46efe79.

This reverts commit 70b57766.

Fixes #3469: Fixed the bug that `QueryBuilder::getColumnType()` may drop the provided column precision in certain cases

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.