Remove Duplicates from Two SQL Columns

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So the situation is this, I have a table and in it I have three fields, so I need to compare the (to = b) and see if there’s anyone like it. What my problem, I’m new in the middle of sql and I’m not being sure if I did it right, I tried it in the following ways.

SELECT DISTINCT [a]
               ,[b]
     FROM [Compara] -- 1 °




SELECT [a]
      ,[b]
     FROM [Compara]

WHERE [a] = [b] --2°

None have returned, so I don’t know if I did it right or wrong, if anyone can help me >.<

mysql sql

  • Brenda, welcome to the O.R. Your question is a bit confused, could you show the structure of your table with some data and put a result you want ? Click on edit I recommend reading on tour to understand a little more how things work here on the network!

1 answer

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Follows:

SELECT CASE WHEN A = B THEN 'Coluna A igual a B' ELSE 'Coluna A diferente da B' END AS COMPARATIVO_01
  FROM TABELA

The SELECT above will return all table data (as I have not used the WHERE), but in return, it will return if the records in column A are different from column B, compared by row.

Now if you just want to return the records in that column A is different from B, use the instruction below:

SELECT *
  FROM TABELA
 WHERE A <> B;

Or to find out if they’re the same:

SELECT *
  FROM TABELA
 WHERE A = B;

Edited

I put the three conditions to make clear to the user the possible possibilities of SQL.

Heed: Like you said you’re still learning SQL, take care not to compare columns of different data. How to compare TRUE or FALSE with VARCHAR.

  • Thank you Lucas , and in this case the two columns are of the same type, in the case of VARCHAR.

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