<TextBox Grid.Column="0"  Style="{StaticResource TextBoxStyle}" Height="30" Text="{Binding CodeBinding, Mode=TwoWay, ValidatesOnExceptions=True}"  Validation.ErrorTemplate="{StaticResource errorTemplateStyle}">TextBox>
public string CodeBinding
{
    get
    {        return code;
    }
    set
    {              
        SetProperty(ref code, value, () => CodeBinding);        if (value==null)
        {            return;
        }
        string sql = "";        //读取数据库,看看编码是否重复        var model=......; 
        if (model!=null)
        {            //编码重复,抛出异常            throw new Exception("人员编码重复"); 
        }
    }
}

调试会报错,运行会显示错误警告"人员编码重复"