ALTER TABLE `Employee` 
ADD COLUMN `TaxClass` varchar(256) NULL DEFAULT NULL AFTER `TaxNumber`,
ADD COLUMN `ChildCount` varchar(256) NULL DEFAULT NULL AFTER `TaxClass`;

ALTER TABLE `EmployeeHistory` 
ADD COLUMN `Employee_TaxClass` varchar(256) NULL DEFAULT NULL AFTER `Employee_TaxNumber`,
ADD COLUMN `Employee_ChildCount` varchar(256) NULL DEFAULT NULL AFTER `Employee_TaxClass`;

ALTER TABLE `Contract` 
ADD COLUMN `GrossSalary` decimal(18,10) NULL DEFAULT NULL AFTER `CancellationPeriod`;

ALTER TABLE `ContractHistory` 
ADD COLUMN `ContractHistoryGrossSalary` decimal(18,10) NULL DEFAULT NULL AFTER `ContractHistoryCancellationPeriod`;