mysqli_stmt::prepare

    mysqli_stmt_prepare

    (PHP 5, PHP 7, PHP 8)

    mysqli_stmt::prepare -- mysqli_stmt_prepare — Prepara uma declaração SQL para execução

    Descrição

    Estilo orientado a objetos

    public mysqli_stmt::prepare(string $query): bool

    Estilo procedural

    mysqli_stmt_prepare(mysqli_stmt $statement, string $query): bool

    Prepara uma declaração para execução. A consulta deve consistir de uma única declaração SQL.

    O modelo de declaração pode conter zero ou mais marcadores de parâmetro que são os pontos de interrogação (?), também chamados de espaços reservados. Os marcadores de parâmetros devem ser ligados às variáveis da aplicação usando mysqli_stmt_bind_param() antes da execução da declaração.

    Nota:

    No caso de uma declaração passada a mysqli_stmt_prepare() ser mais longa que o parâmetro max_allowed_packet do servidor, os códigos de erro retornados serão diferentes dependendo se está sendo utilizando o driver nativo MySQL (mysqlnd) ou a biblioteca cliente do MySQL (libmysqlclient). O comportamento é o seguinte:

    • mysqlnd no Linux retorna o código de erro 1153. A mensagem de erro diz got a packet bigger than (recebido pacote maior que) max_allowed_packet bytes.

    • mysqlnd no Windos retorna o código de erro 2006. Esta mensagem de erro diz server has gone away (servidor se foi).

    • libmysqlclient em todas as plataformas a retorna o código de erro 2006. Esta mensagem de erro diz server has gone away (servidor se foi).

    Parâmetros

    statement

    Somente no estilo procedural: Um objeto mysqli_stmt retornado por mysqli_stmt_init().

    query

    A consulta, como uma string. Deve consistir de uma única declaração SQL.

    A declaração SQL pode conter zero ou mais marcadores de parâmetros representados por caracteres de ponto de interrogação (?) nas posições apropriadas.

    Nota:

    Os marcadores são permitidos somente em alguns lugares das declarações SQL. Por exemplo, eles são permitidos na lista VALUES() de Uma declaração INSERT (para especificar valores de colunas para uma linha), ou em uma comparação com uma coluna em uma cláusula WHERE para especificar um valor de comparação. Entretanto, não são permitidos para identificadores (como tabelas ou nomes de colunas).

    Valor Retornado

    Retorna true em caso de sucesso ou false em caso de falha.

    Erros/Exceções

    Se o relatório de erros da extensão mysqli estiver habilitado (MYSQLI_REPORT_ERROR) e a operação solicitada falhar, um aviso será gerado. Se, além disso, o modo for definido como MYSQLI_REPORT_STRICT, uma exceção mysqli_sql_exception será lançada em vez do aviso.

    Exemplos

    Exemplo #1 Exemplo de mysqli_stmt::prepare()

    Estilo orientado a objetos

    <?php

    mysqli_report    (MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
    $mysqli = new mysqli("localhost", "my_user", "my_password", "world");

    $city = "Amersfoort";

    /* cria uma declaração preparada */
    $stmt = $mysqli->stmt_init();
    $stmt->prepare("SELECT District FROM City WHERE Name=?");

    /* liga parâmetros para os marcadores */
    $stmt->bind_param("s", $city);

    /* executa a consulta */
    $stmt->execute();

    /* liga o resultado à variável */
    $stmt->bind_result($district);

    /* obtém o valor */
    $stmt->fetch();

    printf("%s está no distrito %s\n", $city, $district);

    Estilo procedural

    <?php

    mysqli_report    (MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
    $link = mysqli_connect("localhost", "my_user", "my_password", "world");

    $city = "Amersfoort";

    /* cria uma declaração preparada */
    $stmt = mysqli_stmt_init($link);
    mysqli_stmt_prepare($stmt, "SELECT District FROM City WHERE Name=?");

    /* liga parâmetros para os marcadores */
    mysqli_stmt_bind_param($stmt, "s", $city);

    /* executa a consulta */
    mysqli_stmt_execute($stmt);

    /* liga o resultado à variável */
    mysqli_stmt_bind_result($stmt, $district);

    /* obtém o valor */
    mysqli_stmt_fetch($stmt);

    printf("%s está no distrito %s\n", $city, $district);

    Os exemplos acima produzirão:

    Amersfoort está no distrito Utrecht

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    Notas Enviadas por Usuários (em inglês) 9 notes

    up
    22
    logos-php at kith dot org
    13 years ago
    Note that if you're using a question mark as a placeholder for a string value, you don't surround it with quotation marks in the MySQL query.

    For example, do this:

    mysqli_stmt_prepare($stmt, "SELECT * FROM foo WHERE foo.Date > ?");

    Do not do this:

    mysqli_stmt_prepare($stmt, "SELECT * FROM foo WHERE foo.Date > '?'");

    If you put quotation marks around a question mark in the query, then PHP doesn't recognize the question mark as a placeholder, and then when you try to use mysqli_stmt_bind_param(), it gives an error to the effect that you have the wrong number of parameters.

    The lack of quotation marks around a string placeholder is implicit in the official example on this page, but it's not explicitly stated in the docs, and I had trouble figuring it out, so figured it was worth posting.
    up
    8
    logos-php at kith dot orgpp
    13 years ago
    Turns out you can't directly use a prepared statement for a query that has a placeholder in an IN() clause.

    There are ways around that (such as constructing a string that consists of n question marks separated by commas, then using that set of placeholders in the IN() clause), but you can't just say IN (?).

    This is a MySQL restriction rather than a PHP restriction, but it's not really documented in the MySQL docs either, so I figured it was worth mentioning here.

    (Btw, turns out someone else had previously posted the info that I put in my previous comment, about not using quotation marks. Sorry for the repeat; not sure how I missed the earlier comment.)
    up
    4
    andrey at php dot net
    19 years ago
    If you select LOBs use the following order of execution or you risk mysqli allocating more memory that actually used

    1)prepare()
    2)execute()
    3)store_result()
    4)bind_result()

    If you skip 3) or exchange 3) and 4) then mysqli will allocate memory for the maximal length of the column which is 255 for tinyblob, 64k for blob(still ok), 16MByte for MEDIUMBLOB - quite a lot and 4G for LONGBLOB (good if you have so much memory). Queries which use this order a bit slower when there is a LOB but this is the price of not having memory exhaustion in seconds.
    up
    2
    kontakt at arthur minus schiwon dot de
    16 years ago
    If you wrap the placeholders with quotation marks you will experience warnings like "Number of variables doesn't match number of parameters in prepared statement" (at least with INSERT Statements).
    up
    1
    ndungi at gmail dot com
    16 years ago
    The `prepare` , `bind_param`, `bind_result`, `fetch` result, `close` stmt cycle can be tedious at times. Here is an object that does all the mysqli mumbo jumbo for you when all you want is a select leaving you to the bare essential `preparedSelect` on a prepared stmt. The method returns the result set as a 2D associative array with the `select`ed columns as keys. I havent done sufficient error-checking and it also may have some bugs. Help debug and improve on it.

    I used the bible.sql db from http://www.biblesql.net/sites/biblesql.net/files/bible.mysql.gz.

    Baraka tele!

    ============================

    <?php

    class DB
    {
    public     $connection;

    #establish db connection
    public function __construct($host="localhost", $user="user", $pass="", $db="bible")
    {
    $this->connection = new mysqli($host, $user, $pass, $db);

    if(    mysqli_connect_errno())
    {
    echo(    "Database connect Error : "
    . mysqli_connect_error($mysqli));
    }
    }

    #store mysqli object
    public function connect()
    {
    return     $this->connection;
    }

    #run a prepared query
    public function runPreparedQuery($query, $params_r)
    {
    $stmt = $this->connection->prepare($query);
    $this->bindParameters($stmt, $params_r);

    if (    $stmt->execute()) {
    return     $stmt;
    } else {
    echo(    "Error in $statement: "
    . mysqli_error($this->connection));
    return     0;
    }

    }

    # To run a select statement with bound parameters and bound results.
    # Returns an associative array two dimensional array which u can easily
    # manipulate with array functions.

    public function preparedSelect($query, $bind_params_r)
    {
    $select = $this->runPreparedQuery($query, $bind_params_r);
    $fields_r = $this->fetchFields($select);

    foreach (    $fields_r as $field) {
    $bind_result_r[] = &${$field};
    }

    $this->bindResult($select, $bind_result_r);

    $result_r = array();
    $i = 0;
    while (    $select->fetch()) {
    foreach (    $fields_r as $field) {
    $result_r[$i][$field] = $$field;
    }
    $i++;
    }
    $select->close();
    return     $result_r;
    }


    #takes in array of bind parameters and binds them to result of
    #executed prepared stmt

    private function bindParameters(&$obj, &$bind_params_r)
    {
    call_user_func_array(array($obj, "bind_param"), $bind_params_r);
    }

    private function     bindResult(&$obj, &$bind_result_r)
    {
    call_user_func_array(array($obj, "bind_result"), $bind_result_r);
    }

    #returns a list of the selected field names

    private function fetchFields($selectStmt)
    {
    $metadata = $selectStmt->result_metadata();
    $fields_r = array();
    while (    $field = $metadata->fetch_field()) {
    $fields_r[] = $field->name;
    }

    return     $fields_r;
    }
    }
    #end of class

    #An example of the DB class in use

    $DB = new DB("localhost", "root", "", "bible");
    $var = 5;
    $query = "SELECT abbr, name from books where id > ?" ;
    $bound_params_r = array("i", $var);

    $result_r = $DB->preparedSelect($query, $bound_params_r);

    #loop thru result array and display result

    foreach ($result_r as $result) {
    echo     $result['abbr'] . " : " . $result['name'] . "<br/>" ;
    }

    ?>
    up
    0
    mhradek AT gmail.com
    16 years ago
    A particularly helpful adaptation of this function and the call_user_func_array function:

    // $params is sent as array($val=>'i', $val=>'d', etc...)

    function db_stmt_bind_params($stmt, $params)
    {
    $funcArg[] = $stmt;
    foreach($params as $val=>$type)
    {
    $funcArg['type'] .= $type;
    $funcArg[] = $val;
    }
    return call_user_func_array('mysqli_stmt_bind_param', $funcArgs);
    }

    Thanks to 'sned' for the code.
    up
    0
    st dot john dot johnson at gmail dot com
    17 years ago
    In reference to what lachlan76 said before, stored procedures CAN be executed through prepared statements as long as you tell the DB to move to the next result before executing again.

    Example (Five calls to a stored procedure):

    <?php
    for ($i=0;$i<5;$i++) {
    $statement = $mysqli->stmt_init();
    $statement->prepare("CALL some_procedure( ? )");

    // Bind, execute, and bind.
    $statement->bind_param("i", 1);
    $statement->execute();
    $statement->bind_result($results);

    while(    $statement->fetch()) {
    // Do what you want with your results.
    }

    $statement->close();

    // Now move the mysqli connection to a new result.
    while($mysqli->next_result()) { }
    }
    ?>

    If you include the last statement, this code should execute without the nasty "Commands out of sync" error.
    up
    -1
    lukaszNOSPAMPLEASE at epas dot pl
    17 years ago
    i've got some bad news for you guys if you haven't found out already.
    the trick with mysqli_next_result() only prevents having the connection dropped after a stored procedure call.
    apparently you can bind parameters for a prepared stored procedure call, but you'll get messed up records from mysqli_stmt_fetch() after mysqli_stmt_bind_result(), at least when the stored procedure itself contains a prepared statement.
    a way to avoid data corruption could be specifying the CLIENT_MULTI_STATEMENTS flag in mysqli_real_connect(), if it wasn't disabled entirely (for security reasons, as they say). another option is to use mysqli_multi_query(), but then you can't bind at all.
    up
    -2
    lachlan76 at gmail dot com
    18 years ago
    Do not try to use a stored procedure through a prepared statement.

    Example:

    <?php
    $statement     = $mysqli->stmt_init();
    $statement->prepare("CALL some_procedure()");
    ?>

    If you attempt to do this, it will fail by dropping the connection during the next query. Use mysqli_multi_query instead.

    Example:

    <?php
    $mysqli    ->multi_query("CALL some_procedure()");
    do
    {
    $result = $mysqli->store_result();

    // Do your processing work here

    $result->free();
    } while(    $mysqli->next_result());
    ?>

    This means that you cannot bind parameters or results, however.
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