Shulou(Shulou.com)06/01 Report--

The left join query condition (ON) should ensure that the condition is unique, otherwise multiple values will be generated

Example:

Select c. Cardholder cc. Cardholder number from `vip_card_ change` as cc left join `vip_ card` as c on cc.card_number=c.card_number and cc.store_key=c.store_key

Instead of:

Select c. Cardholder cc. Cardholder number from `vip_card_ change` as cc left join `vip_ card` as c on cc.card_number=c.card_number

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