Find two MySQL tables and select rows with one element in common

There are lots of ways to use the ForEach loop, as a basis for your question, I've put together a simple example to show use of Join and Foreach.

Construction of the bank (Note that I used the data provided by you):

Code:

CREATETABLEEventos(IDINTAUTO_INCREMENTPRIMARYKEY,EventoNVARCHAR(100)NOTNULL,DataEventoDATETIME,Valordecimal);CREATETABLEControle(IDINTAUTO_INCREMENTPRIMARYKEY,MesaINTNOTNULL,ClienteNVARCHAR(100),EventoIDINT,CONSTRAINTFK_EventoDaMesaFOREIGNKEY(EventoID)REFERENCESEventos.ID);INSERTINTOEventos(Evento,DataEvento,Valor)VALUES('EventoA','2018-02-23',20.00);INSERTINTOEventos(Evento,DataEvento,Valor)VALUES('EventoB','2018-02-21',15.00);INSERTINTOControle(Mesa,Cliente,EventoID)VALUES(25,'ClienteX',1);INSERTINTOControle(Mesa,Cliente,EventoID)VALUES(40,'ClienteX',2);INSERTINTOControle(Mesa,Cliente,EventoID)VALUES(34,'ClienteX',1);INSERTINTOControle(Mesa,Cliente,EventoID)VALUES(55,'ClienteX',2);SELECTC.Mesa,C.Cliente,E.Evento,E.DataEvento,E.ValorFROMControleASCINNERJOINEventosASEONC.ID=E.ID;

Usingforeachinhtml+php(thereareseveralwaystodoit):

Code:

foreach($pdo->query($query)as$linha){echo("<table>
                <tr><th>$linha[2]</th></tr> 
                <tr><td>Mesa: $linha[0]</td></tr>
                <tr><td>Cliente: $linha[1]</td></tr>
                <tr><td>Data: $linha[3]</td></tr>
                <tr><td>Valor: $linha[4]</td></tr>
             </table");         
    }

As requested a table for each event (I just did not understand why to display a column with event name if the table header already informs which event it is):

NEW IMAGE WITH CORRECTION

I'mcrawlinginPHPandasI'mnot"throwing in the towel", I did a search and browsing the PHP documentation, I found a class called RecursiveIteratorIterator ... searching deeper I found an example where this class was used for increment rows of a table with the return of the array generated by the Fetch property. I soon saw the possibilities. PHP Documentation - RecursiveIteratorIterator Class

I hope I have helped you find your solution, as I am very happy with the discovery of this class.

How can you see very simple and functional. I did not bother creating a connection class because no connection was requested in the question.

I did not quite understand your question, but in php I would do so

<?php
$mysqli = new mysqli("host", "user", "password", "db");

if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}

$evento = $_POST['evento'];

if ($sth = $mysqli->query("SELECT * FROM tabelas_um WHERE evento = '$evento'")){
while ($row = $sth->fetch_assoc()) 
{
    //Aqui tu faz oq quer
     //Ex: imprimir os dados
       echo "Mesa: " . $row['mesa'] . " Nome: " . $row['nome'];

}
}else{
     echo "Nada encontrado!";
}

As I said, I did not quite understand your question, but see if it satisfies you.

Doing with INNER JOIN would be the clearest and perhaps performative way to solve this problem, query would be something like this:

SELECT b.* FROM 'tabela_dois' a
INNER JOIN 'tabela_um' b ON a.'evento' = b.'evento';

To do with foreach would look something like this:

foreach ($tabelaDois as $linhaTabelaDois){
    foreach ($tabelaUM as $linhaTabelaUM){
        if ($linhaTabelaDois["evento"] == $linhaTabelaUM["evento"]){
            echo "
                <tr>
                    <td>".$linhaTabelaUM['mesa']."</td>
                    <td>".$linhaTabelaUM['nome']."</td>
                <tr>
            ";
        }
    }
}