DISTINCT *不撤消重复性（MYSQL）

Question

i already done everything to remove this duplicity on the database On selecting a checkbox on the sectio "Bairros" i utilized as Array

for($m=0; $m<count($_POST["bairros"]); $m++){// LOOP 1
    $pesquisar=($_POST["bairros"][$m]);
    //Copy bairros(Array) and esporte (POST)
    $query = "SELECT DISTINCT * FROM cadastro WHERE
    (esporte1 = '".$_POST["esportes"]."' OR
    esporte2 = '".$_POST["esportes"]."' OR
    esporte3 = '".$_POST["esportes"]."' OR
    esporte4 = '".$_POST["esportes"]."')
    AND
    (bairro1 = '".$pesquisar."' OR
    bairro2 = '".$pesquisar."' OR
    bairro3 = '".$pesquisar."' OR
    bairro4 = '".$pesquisar."')
    AND
    ativarAparecer='sim' ORDER BY nomeCompleto ASC LIMIT 20";
    $esporte= new consultar();
    $esporte->executa($query);
    //Loops  
    for($l=0; $l<$esporte->nrw; $l++){ //LOOP 2
        echo $esporte->data["nomeCompleto"]."<br />";
        $esporte->proximo();
    } //close LOOP2
} //close LOOP1

• Detail: this function object oriented, I believe that i'm doing something wrong at SQL or MYSQL, perhaps something is missing there.

Answer 1

SELECT DISTINCT *

Stop There. DISTINCT * can do what? Duplicate of what? it cant do that. Give it a field name to see unique values.

For example

SELECT DISTINCT nomeCompleto

Answer 2

Let's break this down. The DISTINCT clause will return unique sets based on the selected columns .

Let's say you have a table:

a | b | c
=========
1 | 2 | 3
1 | 1 | 3
1 | 2 | 4

Now if you SELECT DISTINCT a FROM table , you would get:

1

but if you SELECT DISTINCT a, b FROM table , you would get:

a | b
=====
1 | 2
1 | 1

That's because {1,2} is different from {1,1} , even though the a column is the same between those two sets.

Obviously, doing SELECT DISTINCT * FROM table would give you the original table because it uses all three columns as a "composition" of the unique set. If we amended the table to look like this:

a | b | c
=========
1 | 2 | 3
1 | 1 | 3
1 | 2 | 4
1 | 2 | 3

Then your result of SELECT DISTINCT * FROM table would give:

a | b | c
=========
1 | 2 | 3
1 | 1 | 3
1 | 2 | 4

because of the duplicate result set of {1, 2, 3} . However, since most tables have an auto-incrementing identifier as the primary key, there is almost always no difference between SELECT * and SELECT DISTINCT * .

Perhaps you're looking to GROUP BY a certain column?

Answer 3

How would I be using GROUP this in my script? Column that there are several equal records are this bairro, bairro2, bairro3, bairro4. Inside it is in numbers

bairro1 | bairro2 | bairro3 | bairro4
     14 |    14   |   15    | 27
     34 |    15   |   14    | 30
     27 |    45   |   12    | 14