从下拉列表中选择“ALL”选项时显示数据库中的数据

I have one dropdown list populating from a database table A. When user select an option and click 'go', related data with that category will display on page from another database table B.Like this, when user select 'ALL' option from dropdown list and click 'Go', It should display all the data from B table. I have one dropdown list populating from a data