新手求帮忙，请大神帮忙解释一下sql语句的问题

请大神帮忙看看，这几句SQL语句有什么语法问题！！！
string sql = "select EmployeeId,EmployeeName,Gender,Birthday,DepartmentName from Employees";
sql += "inner join EmployeeDepartment on Employees.DepartmentId=EmployeeDepartment.DepartmentId";
sql += "where Employees.DepartmentId="+departmentId;
执行后的语句是这样：

where那好像没有隔开，求大神教具体应该怎么改