场景：选择客户后，再选择品牌，只显示客户品牌（客户定义几个品牌）
IF EXISTS (select b.Brand,b.code,cb.* from M_Tabs_CustomerBrand cb left join M_Brand b on cb.BrandID=b.BrandID where CustomerID=:CustomerID)
begin
select b.Brand,b.code,cb.* from M_Tabs_CustomerBrand cb left join M_Brand b on cb.BrandID=b.BrandID where CustomerID=:CustomerID
end
else
begin
select * from M_Brand
end
