摘要：
Write a SQL query to delete all duplicate email entries in a table named Person, keeping only unique emails based on its smallest Id. For example, aft 阅读全文
posted @ 2018-01-20 17:18
__Meng
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摘要：
Given a Weather table, write a SQL query to find all dates' Ids with higher temperature compared to its previous (yesterday's) dates. For example, ret 阅读全文
posted @ 2018-01-20 17:03
__Meng
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摘要：
Given a table salary, such as the one below, that has m=male and f=female values. Swap all f and m values (i.e., change all f values to m and vice ver 阅读全文
posted @ 2018-01-20 13:25
__Meng
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