标签:stat follow query keep exec code his win should
Write a SQL query to delete all duplicate email entries in a table named Person
, keeping only unique emails based on its smallest Id.
+----+------------------+ | Id | Email | +----+------------------+ | 1 | john@example.com | | 2 | bob@example.com | | 3 | john@example.com | +----+------------------+ Id is the primary key column for this table.
For example, after running your query, the above Person
table should have the following rows:
+----+------------------+ | Id | Email | +----+------------------+ | 1 | john@example.com | | 2 | bob@example.com | +----+------------------+
Note:
Your output is the whole Person
table after executing your sql. Use delete
statement.
Code
DELETE p2 FROM Person AS p1, Person As p2 WHERE p1.Email = p2.Email AND p1.Id < p2.Id
[LeetCode] 196. Delete Duplicate Emails_Easy tag: SQL
标签:stat follow query keep exec code his win should
原文地址:https://www.cnblogs.com/Johnsonxiong/p/9490988.html