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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
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The Employee table holds all employees. Every employee has an Id, and there is also a column for the department Id. The Department table holds all dep 阅读全文
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The Employee table holds all employees. Every employee has an Id, a salary, and there is also a column for the department Id. The Department table hol 阅读全文
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Given an array of strings, group anagrams together. For example, given: ["eat", "tea", "tan", "ate", "nat", "bat"], Return: 解法1： 把含有相同字母的字符串分之同一组，对每组的 阅读全文
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Suppose that a website contains two tables, the Customers table and the Orders table. Write a SQL query to find all customers who never order anything 阅读全文
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Write a SQL query to find all duplicate emails in a table named Person. 阅读全文
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The Employee table holds all employees including their managers. Every employee has an Id, and there is also a column for the manager Id. Given the Em 阅读全文
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Write a SQL query to find all numbers that appear at least three times consecutively. For example, given the above Logs table, 1 is the only number th 阅读全文
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Write a SQL query to rank scores. If there is a tie between two scores, both should have the same ranking. Note that after a tie, the next ranking num 阅读全文
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Write a SQL query to get the nth highest salary from the Employee table. For example, given the above Employee table, the nth highest salary where n = 阅读全文