有两个表：表a与表b，表b是表a的备份表，字段结构一样，a，b两表为复合主键，请删除b表中与a表主键相同的字段

有两个表：表a与表b，表b是表a的备份表，字段结构一样，a，b两表为复合主键，请删除b表中与a表主键相同的字段

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delete  from a where exists (select null from b  WHERE a.firstName=b.firstName and a.lastName=b.lastName)

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