bill_price表[資料多]
| goods_name | goods_standard | goods_maerial | goods_factoy | city_name |
sale_market表[資料多]
| goods_name | goods_standard | goods_maerial | goods_factoy | city_name |
q:查出bill_price表中資料不再[sale_market]表中的資料 ;目的:將查處的資料寫入[sale_market];
[當建立了5欄位索引後,查詢效率提高很多]
語句1:
select count(*) from bill_price where bill_price_id not in(select b.bill_price_id from bill_price as b, sale_market as s where s.goods_name = b.goods_name and s.goods_material = b.g;oods_material and s.goods_standard = b.goods_standard and s.goods_factory = b.goods_factory and s.city_name =b.city_name );
語句2:
select count(*) from bill_price b where not exists (select 1 from sale_market s where s.goods_name = b.goods_name and s.goods_material = b.goods_material and s.goods_standard = b.goods_standard and s.goods_factory = b.goods_factory and s.city_name =b.city_name );
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