Compare Mysql search results

Question

I need to compare the result of a query not to repeat the result.

For example: I have in the unit register your Cod and speed, but I can have 2 situations:

1) more than one occurrence for the same unit and different speeds, and need to be listed only the occurrence of the higher speed.

cod  - velocidade
100  - 128
100  - 512

as a result of the search I need to list only the most valuable: 100 - 512

2) I can also return more occurrences with the same information, however I need to list only one of them:

cod - velocidade
105 - 512
105 - 512
105 - 512

I need to list only 1x: 105 - 512

How can I be doing these checks?

Answer 1

Felipe uses SQL aggregation function.

SELECT COD, MAX(VELOCIDADE 
  FROM TABELA
  GROUP BY COD

Done. sql will group by code all speeds and display only the highest.

Group functions by

group by

Examples of group by

Answer 2

In question 1 you can do as follows:

SELECT MAX(velocidade) AS velocidade FROM tabela WHERE cod = 100;

In question 2 you can do as follows:

SELECT DISTINCT cod, velocidade FROM tabela WHERE cod = 105 AND velocidade = 512