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Is there a way to store an array into mysql field? I'm creating a comment rating system so I want to store the arrays of user ids to prevent multiple votings. I'm going to create new table that holds the comment id and the array of user ids who have voted on this comment. Than I'll join comments table and this table and check whether the current user id exists in the voters array or note. If it does than the voting icons would be disabled. I think I'll prevent to use mysql query in loop in this way.

Do you happen to know any better ways?

 Answers

1

You can always serialize the array and store that in the database.
PHP Serialize

You can then unserialize the array when needed.

Monday, November 21, 2022
5

You could build the query programatically...:

$sql = 'INSERT INTO table (memberID, programID) VALUES ';
$insertQuery = array();
$insertData = array();
foreach ($data as $row) {
    $insertQuery[] = '(?, ?)';
    $insertData[] = $memberid;
    $insertData[] = $row;
}

if (!empty($insertQuery)) {
    $sql .= implode(', ', $insertQuery);
    $stmt = $db->prepare($sql);
    $stmt->execute($insertData);
}
Wednesday, August 24, 2022
4

Assign

$_SESSION['question'] = $que; 

print_r($_SESSION['question'][0]); will give you first question.

Friday, November 18, 2022
4

MySQL has a different timeout than PHP. You could increase it in php.ini on the line mysql.connect_timeout = 14400. Also increase the default_socket_timeout = 14400

Note that if your PHP setting allow you to do an ini_set, you can also do as follows:

ini_set('mysql.connect_timeout', 14400);
ini_set('default_socket_timeout', 14400);
Thursday, December 22, 2022
 
plutor
 
1

The details are implementation dependent but generally speaking, results are buffered. Executing a query against a database will return some result set. If it's sufficiently small all the results may be returned with the initial call or some might be and more results are returned as you iterate over the result object.

Think of the sequence this way:

  1. You open a connection to the database;
  2. There is possibly a second call to select a database or it might be done as part of (1);
  3. That authentication and connection step is (at least) one round trip to the server (ignoring persistent connections);
  4. You execute a query on the client;
  5. That query is sent to the server;
  6. The server has to determine how to execute the query;
  7. If the server has previously executed the query the execution plan may still be in the query cache. If not a new plan must be created;
  8. The server executes the query as given and returns a result to the client;
  9. That result will contain some buffer of rows that is implementation dependent. It might be 100 rows or more or less. All columns are returned for each row;
  10. As you fetch more rows eventually the client will ask the server for more rows. This may be when the client runs out or it may be done preemptively. Again this is implementation dependent.

The idea of all this is to minimize roundtrips to the server without sending back too much unnecessary data, which is why if you ask for a million rows you won't get them all back at once.

LIMIT clauses--or any clause in fact--will modify the result set.

Lastly, (7) is important because SELECT * FROM table WHERE a = 'foo' and SELECT * FROM table WHERE a = 'bar' are two different queries as far as the database optimizer is concerned so an execution plan must be determined for each separately. But a parameterized query (SELECT * FROM table WHERE a = :param) with different parameters is one query and only needs to be planned once (at least until it falls out of the query cache).

Thursday, October 20, 2022
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