mysql_query
(PHP 4, PHP 5, PECL mysql:1.0)
mysql_query — Посылает запрос MySQL
Описание
mysql_query() посылает запрос активной базе данных сервера, на который ссылается переданный указатель. Если параметр link_identifier опущен, используется последнее открытое соединение. Если открытые соединения отсутствуют, функция пытается соединиться с СУБД, аналогично функции mysql_connect() без параметров. Результат запроса буфферизируется.
Замечание: Строка запроса НЕ должна заканчиваться точкой с запятой.
Только для запросов SELECT, SHOW, EXPLAIN, DESCRIBE, mysql_query() возвращает указатель на результат запроса, или FALSE если запрос не был выполнен. В остальных случаях, mysql_query() возвращает TRUE в случае успешного запроса и FALSE в случае ошибки. Значение не равное FALSE говорит о том, что запрос был выполнен успешно. Он не говорит о количестве затронутых или возвращённых рядов. Вполне возможна ситуация, когда успешный запрос не затронет ни одного ряда.
Следующий запрос составлен неправильно и mysql_query() вернёт FALSE:
Пример #1 Пример использования mysql_query()
<php
$result = mysql_query("SELECT * WHERE 1=1")
or die("Invalid query: " . mysql_error());
?>
Следующий запрос ошибочен, если колонки my_col нет в таблице my_tbl, в таком случае mysql_query() вернёт FALSE:
Пример #2 Пример использования mysql_query()
<?php
$result = mysql_query("SELECT my_col FROM my_tbl")
or die("Invalid query: " . mysql_error());
?>
mysql_query() также считается ошибочным и вернёт FALSE, если у вас не хватает прав на работу с указанной в запросе таблицей.
Работая с результатами запросов, вы можете использовать функцию mysql_num_rows(), чтобы найти число, возвращённых запросом SELECT, рядов, или mysql_affected_rows(), чтобы найти число рядов, обработанных запросами DELETE, INSERT, REPLACE, или UPDATE.
Только для запросов SELECT, SHOW, DESCRIBE, EXPLAIN, функция mysql_query() возвращает указатель на результат, который можно использовать в функции mysql_fetch_array() и других функциях, работающих с результатами запросов. Когда работа с результатом окончена, вы можете освободить ресурсы, используемые для его хранения, с помощью функции mysql_free_result(), хотя память в любом случае будет очищена в конце исполнения скрипта.
См. также mysql_num_rows(), mysql_affected_rows(), mysql_unbuffered_query(), mysql_free_result(), mysql_fetch_array(), mysql_fetch_row(), mysql_fetch_assoc(), mysql_result(), mysql_select_db() и mysql_connect().
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Коментарии
When trying to INSERT or UPDATE and trying to put a large amount of text or data (blob) into a mysql table you might run into problems.
In mysql.err you might see:
Packet too large (73904)
To fix you just have to start up mysql with the option -O max_allowed_packet=maxsize
You would just replace maxsize with the max size you want to insert, the default is 65536
Until this function prohibits them, watch out for SQL comments (--) in your input.Regarding the idea for returning all possible values of an enum field, the mySQL manual says that "SHOW COLUMNS FROM table LIKE column" should be used to do this.
The function below (presumes db connection) will return an array of the possible values of an enum.
function GetEnumValues($Table,$Column)
{
$dbSQL = "SHOW COLUMNS FROM ".$Table." LIKE '".$Column."'";
$dbQuery = mysql_query($dbSQL);
$dbRow = mysql_fetch_assoc($dbQuery);
$EnumValues = $dbRow["Type"];
$EnumValues = substr($EnumValues, 6, strlen($EnumValues)-8);
$EnumValues = str_replace("','",",",$EnumValues);
return explode(",",$EnumValues);
}
Cavaets:
1) If the LIKE matches more than one column you get the enum from the first, so be careful with the $Column argument
2) You can't have ',' as part of one of the enums (I guess mySQL would escape this, but I haven't tried)
3) If the field isn't an enum you'll get garbage back!
This is just a quick example to show how to do it, some tidying up needs to be done (ie checking if the field is actually an enum) before it is perfect.
I believe there is a typo in celtic at raven-blue dot com version with:
if (($sql != "") && (substr($tsl, 0, 2) != "--") && (substr($tsl, 0, 1) != "#")) {
I think you really ment:
if (($tsl != "") && (substr($tsl, 0, 2) != "--") && (substr($tsl, 0, 1) != "#")) {
I changed the $sql to $tsl
If, like me, you come from perl, you may not like having to use sprintf to 'simulate' placeholders that the DBI package from perl provides. I have created the following wrapper function for mysql_query() that allows you to use '?' characters to substitute values in your DB queries. Note that this is not how DBI in perl handles placeholders, but it's pretty similar.
<?php
// mysql_query() wrapper. takes two arguments. first
// is the query with '?' placeholders in it. second argument
// is an array containing the values to substitute in place
// of the placeholders (in order, of course).
function mysql_prepare ($query, $phs = array()) {
foreach ($phs as $ph) {
$ph = "'" . mysql_real_escape_string($ph) . "'";
$query = substr_replace(
$query, $ph, strpos($query, '?'), 1
);
}
return mysql_query($query);
}
// sample usage
list($user, $passwd) = array('myuser', 'mypass');
$sth = mysql_prepare(
'select userid from users where userid=? and passwd=?',
array($user, sha1($passwd))
);
$row = mysql_fetch_row($sth);
// successfull username & password authentication
if ($row !== false) {
echo "logging in as '{$row[0]}'!\n";
}
// oops, wrong userid or passwd
else {
echo "Invalid username and password combination.\n";
}
?>
Note that the 'source' command used in the mysql client program is *not* a feature of the server but of the client.This means that you cannot do
mysql_query('source myfile.sql');
You will get a syntax error. Use LOAD DATA INFILE as an alternative.
Here's a parameterised query function for MySQL similar to pg_query_params, I've been using something similar for a while now and while there is a slight drop in speed, it's far better than making a mistake escaping the parameters of your query and allowing an SQL injection attack on your server.
<?php # Parameterised query implementation for MySQL (similar PostgreSQL's PHP function pg_query_params)
# Example: mysql_query_params( "SELECT * FROM my_table WHERE col1=$1 AND col2=$2", array( 42, "It's ok" ) );
if( !function_exists( 'mysql_query_params' ) ) {
function mysql_query_params__callback( $at ) {
global $mysql_query_params__parameters;
return $mysql_query_params__parameters[ $at[1]-1 ];
}
function mysql_query_params( $query, $parameters=array(), $database=false ) {
// Escape parameters as required & build parameters for callback function
global $mysql_query_params__parameters;
foreach( $parameters as $k=>$v )
$parameters[$k] = ( is_int( $v ) ? $v : ( NULL===$v ? 'NULL' : "'".mysql_real_escape_string( $v )."'" ) );
$mysql_query_params__parameters = $parameters;
// Call using mysql_query
if( false===$database )
return mysql_query( preg_replace_callback( '/\$([0-9]+)/', 'mysql_query_params__callback', $query ) );
else return mysql_query( preg_replace_callback( '/\$([0-9]+)/', 'mysql_query_params__callback', $query ), $database );
}
}
?>
this could be a nice way to print values from 2 tables with a foreign key. i have not yet tested correctly but it should work fine.
$buscar = mysql_query("SELECT k.*, e.Clasificacion FROM cat_plan_k k, cat_equipo e WHERE Tipo='$tipo' AND k.ID_Eq=a.ID_Eq");
while ($row=mysql_fetch_array($buscar))
{
$nombre = "e.Clasificacion";
$row[$nombre] = $Clasific; echo $row[$nombre].'convertido en '.$Clasific;
}
mysql_free_result($buscar);
Simulating an atomic operation for application locks using mysql.
$link = mysql_connect('localhost', 'user', 'pass');
if (!$link) {
die('Not connected : ' . mysql_error());
}
// make foo the current db
$db_selected = mysql_select_db('foo', $link);
if (!$db_selected) {
die ('Can\'t use foo : ' . mysql_error());
}
$q = "update `table` set `LOCK`='F' where `ID`='1'";
$lock = mysql_affected_rows();
If we assume
NOT LOCKED = "" (empty string)
LOCKED = 'F'
then if the column LOCK had a value other than F (normally should be an empty string) the update statement sets it to F and set the affected rows to 1. Which mean than we got the lock.
If affected rows return 0 then the value of that column was already F and somebody else has the lock.
The secret lies in the following statement taken from the mysql manual:
"If you set a column to the value it currently has, MySQL notices this and does not update it."
Of course all this is possible if the all application processes agree on the locking algorithm.
mysql_query doesnt support multiple queries, a way round this is to use innodb and transactions
this db class/function will accept an array of arrays of querys, it will auto check every line for affected rows in db, if one is 0 it will rollback and return false, else it will commit and return true, the call to the function is simple and is easy to read etc
----------
class MySQLDB
{
private $connection; // The MySQL database connection
/* Class constructor */
function MySQLDB(){
/* Make connection to database */
$this->connection = mysql_connect(DB_SERVER, DB_USER, DB_PASS) or die(mysql_error());
mysql_select_db(DB_NAME, $this->connection) or die(mysql_error());
}
/* Transactions functions */
function begin(){
$null = mysql_query("START TRANSACTION", $this->connection);
return mysql_query("BEGIN", $this->connection);
}
function commit(){
return mysql_query("COMMIT", $this->connection);
}
function rollback(){
return mysql_query("ROLLBACK", $this->connection);
}
function transaction($q_array){
$retval = 1;
$this->begin();
foreach($q_array as $qa){
$result = mysql_query($qa['query'], $this->connection);
if(mysql_affected_rows() == 0){ $retval = 0; }
}
if($retval == 0){
$this->rollback();
return false;
}else{
$this->commit();
return true;
}
}
};
/* Create database connection object */
$database = new MySQLDB;
// then from anywhere else simply put the transaction queries in an array or arrays like this:
function function(){
global $database;
$q = array (
array("query" => "UPDATE table WHERE something = 'something'"),
array("query" => "UPDATE table WHERE something_else = 'something_else'"),
array("query" => "DELETE FROM table WHERE something_else2 = 'something_else2'"),
);
$database->transaction($q);
}
Keep in mind when dealing with PHP & MySQL that sending a null-terminated string to a MySQL query can be misleading if you use echo($sql) in PHP because the null terminator may not be visible.
For example (this assumes connection is already made),
$string1 = "mystring\0";
$string2 = "mystring";
$query1 = "SELECT * FROM table WHERE mystring='".$string1."'"
$query2 = "SELECT * FROM table WHERE mystring='".$string2."'"
$result1 = mysql_query($query1);
$result2 = mysql_query($query2);
//$result1 IS NOT EQUAL TO $result2 but will not provide an error
//but printing these queries to the screen will provide the same result
echo($result1);
echo($result2);
Not knowing this could lead to some mind-numbing troubleshooting when dealing with any strings with a null terminator. So now you know! :)
It should be noted that mysql_query can generate an E_WARNING (not documented). The warning that I hit was when the db user did not have permission to execute a UDF.
Expected behavior would be like an Invalid SQL statement, where there is no E_WARNING generated by mysql_query.
Warning: mysql_query() [function.mysql-query]: Unable to save result set in filename.php
The mysql_errno is 1370 and the mysql_error is:
execute command denied to user 'username'@'%' for routine 'database_name.MyUDF'
When you run a select statement and receive a response, the data types of your response will be a string regardless of the data type of the column.
<?php
// Query to select an int column
$query = 'SELECT user_id FROM users WHERE user_id = 1';
$result = mysql_query($query);
$array = mysql_fetch_assoc($result);
// Echoes: string
echo gettype($array['user_id']);
?>
Use this to neatly insert data into a mysql table:
<?php
function mysql_insert($table, $inserts) {
$values = array_map('mysql_real_escape_string', array_values($inserts));
$keys = array_keys($inserts);
return mysql_query('INSERT INTO `'.$table.'` (`'.implode('`,`', $keys).'`) VALUES (\''.implode('\',\'', $values).'\')');
}
?>
For example:
<?php
mysql_insert('cars', array(
'make' => 'Aston Martin',
'model' => 'DB9',
'year' => '2009',
));
?>
This project implements a wrapper to mysql functions in PHP7.0+
https://github.com/OOPS-ORG-PHP/mysql-extension-wrapper
tested and working fine =)