???SQL SELECT????????6????????

???????JOIN??WHERE????е???????
?????????????????????????????????????????????????????????????????С??????????????????????????????????????????д?????????????SQL???
????FROM sales a
????JOIN budget b ON    ((YEAR(a.sale_date)* 100) + MONTH(a.sale_date)) = b.budget_year_month
??????sales???????????????????У????????????????o??SQL??佫????:
????SELECT * FROM PRODUCTSFROM sales a
????JOIN budget b ON    a.sale_year_month = b.budget_year_month
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????· ?????JOIN??WHERE????е???????
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