Select all the correct answersWrite a SQL query to delete all duplicate email entries in a table named Person, keeping only unique emails based on its smallest [email protected]@[email protected] is the primary key column for this table.For example, after running your query, the above Person table should have the following rows:[email protected]@example.comNote: Your output is the whole Person table after executing your sql. Use delete statement.Optionsdelete p.* from Person as p, ( select Email, min(Id) as minId from Person where having count(*) > 1) as q where p.Email = q.Email and Id > q.minId;delete p1 from Person as p1, Person as p2where p1.Email = p2.Email and p1.Id > p2.Id;delete p.* from Person as p, ( select Email, min(Id) as minId from Person group by Email having count(*) > 1) as q where p.Email = q.Email and Id > q.minId;delete p1 from Person as p1, Person as p2where p1.Email != p2.Email and p1.Id <= p2.Id;Finish ClearPrev
Question
Select all the correct answersWrite a SQL query to delete all duplicate email entries in a table named Person, keeping only unique emails based on its smallest [email protected]@[email protected] is the primary key column for this table.For example, after running your query, the above Person table should have the following rows:[email protected]@example.comNote: Your output is the whole Person table after executing your sql. Use delete statement.Optionsdelete p.* from Person as p, ( select Email, min(Id) as minId from Person where having count() > 1) as q where p.Email = q.Email and Id > q.minId;delete p1 from Person as p1, Person as p2where p1.Email = p2.Email and p1.Id > p2.Id;delete p. from Person as p, ( select Email, min(Id) as minId from Person group by Email having count(*) > 1) as q where p.Email = q.Email and Id > q.minId;delete p1 from Person as p1, Person as p2where p1.Email != p2.Email and p1.Id <= p2.Id;Finish ClearPrev
Solution
The correct SQL query to delete all duplicate email entries in the table named Person, keeping only unique emails based on its smallest Id is:
delete p1 from Person as p1, Person as p2
where p1.Email = p2.Email and p1.Id > p2.Id;
This query works by joining the Person table to itself on the Email field. It then deletes rows where the Id in the first instance of the table (p1) is greater than the Id in the second instance of the table (p2). This effectively keeps only the row with the smallest Id for each email.
Similar Questions
Write a SQL query to find all duplicate emails in a table named [email protected]@[email protected] example, your query should return the following for the above table:[email protected]Note: All emails are in lowercase.Optionsselect Email from Person group by Email having count(Email) <= 1;select Email group by Email having count(Email) > 1;select Email from Person group by Email having count(Email) > 1;select Email from Person group by Email having count(Email) ;
eid ename esalary email dob1 XYZ 3000.89 [email protected] 1990-08-302 ABC 2300.90 [email protected] 1980-03-211] Write Query to insert 2 Records in above table using single query.2]Write Query to update esalary to 4000.68 and dob to 1993-08-30 of employee whose eid is 1 in a single query.3] Write Query to delete all records from the table in single query.
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How can you remove duplicate rows from a result set in SQL?
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