This may or may not be obvious to people but perhaps it will help someone.
When running joins in SQL you may encounter a problem if you are trying to pull two columns with the same name. mysqli returns the last in the query when called by name. So to get what you need you can use an alias.
Below I am trying to join a user id with a user role. in the first table (tbl_usr), role is a number and in the second is a text name (tbl_memrole is a lookup table). If I call them both as role I get the text as it is the last "role" in the query. If I use an alias then I get both as desired as shown below.
<?php
$sql = "SELECT a.uid, a.role AS roleid, b.role,
FROM tbl_usr a
INNER JOIN tbl_memrole b
ON a.role = b.id
";
if ($result = $mysqli->query($sql)) {
while($obj = $result->fetch_object()){
$line.=$obj->uid;
$line.=$obj->role;
$line.=$obj->roleid;
}
}
$result->close();
unset($obj);
unset($sql);
unset($query);
?>
In this situation I guess I could have just renamed the role column in the first table roleid and that would have taken care of it, but it was a learning experience.
PHP - Manual: mysqli::query
2024-11-14
mysqli::query
mysqli_query
(PHP 5, PHP 7, PHP 8)
mysqli::query -- mysqli_query — 对数据库执行一次查询
说明
面向对象风格
过程化风格
Performs a query against the database.
For non-DML queries (not INSERT, UPDATE or DELETE), this function is similar to calling mysqli_real_query() followed by either mysqli_use_result() or mysqli_store_result().
注意:
In the case where you pass a statement to mysqli_query() that is longer than
max_allowed_packetof the server, the returned error codes are different depending on whether you are using MySQL Native Driver (mysqlnd) or MySQL Client Library (libmysqlclient). The behavior is as follows:
mysqlndon Linux returns an error code of 1153. The error message meansgot a packet bigger than.max_allowed_packetbytes
mysqlndon Windows returns an error code 2006. This error message meansserver has gone away.
libmysqlclienton all platforms returns an error code 2006. This error message meansserver has gone away.
参数
-
mysql -
仅以过程化样式：由mysqli_connect() 或 mysqli_init() 返回的 mysqli 对象。
-
query -
The query string.
Data inside the query should be properly escaped.
-
resultmode -
Either the constant
MYSQLI_USE_RESULTorMYSQLI_STORE_RESULTdepending on the desired behavior. By default,MYSQLI_STORE_RESULTis used.If you use
MYSQLI_USE_RESULTall subsequent calls will return errorCommands out of syncunless you call mysqli_free_result()With
MYSQLI_ASYNC(available with mysqlnd), it is possible to perform query asynchronously. mysqli_poll() is then used to get results from such queries.
返回值
失败时返回 false，通过mysqli_query() 成功执行SELECT, SHOW, DESCRIBE或
EXPLAIN查询会返回一个mysqli_result 对象，其他查询则返回true。
更新日志
| 版本 | 说明 |
|---|---|
| 5.3.0 | Added the ability of async queries. |
范例
示例 #1 mysqli::query() example
面向对象风格
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* check connection */
if ($mysqli->connect_errno) {
printf("Connect failed: %s\n", $mysqli->connect_error);
exit();
}
/* Create table doesn't return a resultset */
if ($mysqli->query("CREATE TEMPORARY TABLE myCity LIKE City") === TRUE) {
printf("Table myCity successfully created.\n");
}
/* Select queries return a resultset */
if ($result = $mysqli->query("SELECT Name FROM City LIMIT 10")) {
printf("Select returned %d rows.\n", $result->num_rows);
/* free result set */
$result->close();
}
/* If we have to retrieve large amount of data we use MYSQLI_USE_RESULT */
if ($result = $mysqli->query("SELECT * FROM City", MYSQLI_USE_RESULT)) {
/* Note, that we can't execute any functions which interact with the
server until result set was closed. All calls will return an
'out of sync' error */
if (!$mysqli->query("SET @a:='this will not work'")) {
printf("Error: %s\n", $mysqli->error);
}
$result->close();
}
$mysqli->close();
?>
过程化风格
<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
/* Create table doesn't return a resultset */
if (mysqli_query($link, "CREATE TEMPORARY TABLE myCity LIKE City") === TRUE) {
printf("Table myCity successfully created.\n");
}
/* Select queries return a resultset */
if ($result = mysqli_query($link, "SELECT Name FROM City LIMIT 10")) {
printf("Select returned %d rows.\n", mysqli_num_rows($result));
/* free result set */
mysqli_free_result($result);
}
/* If we have to retrieve large amount of data we use MYSQLI_USE_RESULT */
if ($result = mysqli_query($link, "SELECT * FROM City", MYSQLI_USE_RESULT)) {
/* Note, that we can't execute any functions which interact with the
server until result set was closed. All calls will return an
'out of sync' error */
if (!mysqli_query($link, "SET @a:='this will not work'")) {
printf("Error: %s\n", mysqli_error($link));
}
mysqli_free_result($result);
}
mysqli_close($link);
?>
以上例程会输出：
Table myCity successfully created. Select returned 10 rows. Error: Commands out of sync; You can't run this command now
参见
- mysqli_real_query() - 执行一个mysql查询
- mysqli_multi_query() - 执行查询
- mysqli_free_result() - Frees the memory associated with a result
add a note
User Contributed Notes 22 notes
NUNTIUS ¶
14 years ago
petrus.jvr ¶
11 years ago
When calling multiple stored procedures, you can run into the following error: "Commands out of sync; you can't run this command now".
This can happen even when using the close() function on the result object between calls.
To fix the problem, remember to call the next_result() function on the mysqli object after each stored procedure call. See example below:
<?php
// New Connection
$db = new mysqli('localhost','user','pass','database');
// Check for errors
if(mysqli_connect_errno()){
echo mysqli_connect_error();
}
// 1st Query
$result = $db->query("call getUsers()");
if($result){
// Cycle through results
while ($row = $result->fetch_object()){
$user_arr[] = $row;
}
// Free result set
$result->close();
$db->next_result();
}
// 2nd Query
$result = $db->query("call getGroups()");
if($result){
// Cycle through results
while ($row = $result->fetch_object()){
$group_arr[] = $row;
}
// Free result set
$result->close();
$db->next_result();
}
else echo($db->error);
// Close connection
$db->close();
?>
theyranos at gmail dot com ¶
11 years ago
The cryptic "Couldn't fetch mysqli" error message can mean any number of things, including:
1. You're trying to use a database object that you've already closed (as noted by ceo at l-i-e dot com). Reopen your database connection, or find the call to <?php mysqli_close($db); ?> or <?php $db->close(); ?> and remove it.
2. Your MySQLi object has been serialized and unserialized for some reason. Define a wakeup function to re-create your database connection. http://php.net/__wakeup
3. Something besides you closed your mysqli connection (in particular, see http://bugs.php.net/bug.php?id=33772)
4. You mixed OOP and functional calls to the database object. (So, you have <?php $db->query() ?> in the same program as <?php mysqli_query($db) ?>).
Anonymous ¶
4 years ago
Here is an example of a clean query into a html table
<table>
<tr>
<th>First Name</th>
<th>Last Name</th>
<th>City</th>
</tr>
<?php while ($row = $myquery->fetch_assoc()) { ?>
<tr>
<td><?php echo $row["firstname"]; ?></td>
<td><?php echo $row["lastname"]; ?></td>
<td><?php echo $row["city"];?></td>
</tr>
<?php } ?>
</table>
Beeners ¶
16 years ago
Stored Procedures.
Use mysqli_query to call a stored procedure that returns a result set.
Here is a short example:
<?php
$mysqli = new mysqli(DBURI,DBUSER,DBPASS,DBNAME);
if (mysqli_connect_errno())
{
printf("Connection failed: %s\n", mysqli_connect_error());
exit();
}
$SQL = "CALL my_procedure($something)";
if ( ($result = $mysqli->query($SQL))===false )
{
printf("Invalid query: %s\nWhole query: %s\n", $mysqli->error, $SQL);
exit();
}
while ($myrow = $result->fetch_array(MYSQLI_ASSOC))
{
$aValue[]=$myrow["a"];
$bValue[]=$myrow["b"];
}
$result->close();
$mysqli->close();
?>
I hope this saves someone some time.
registrations at jdfoxmicro dot com ¶
12 years ago
I like to save the query itself in a log file, so that I don't have to worry about whether the site is live.
For example, I might have a global function:
<?php
function UpdateLog ( $string , $logfile ) {
$fh = fopen ( $logfile , 'a' );
$fwrite ( $fh , strftime ('%F %T %z')." ".$string."\n";
fclose ( $fh );
}
?>
Then in my mysql function error trapper, something like this:
<?php
$error_msg = "Database error in [page].php / ";
$error_msg .= mysqli_error ( $link )." / ";
$error_msg .= $query;
UpdateLog ( $error_msg , DB_ERROR_LOG_FILE );
?>
I also include the remote IP, user agent, etc., but I left it out of these code samples. And have it e-mail me when an error is caught, too.
Jeff
ceo at l-i-e dot com ¶
13 years ago
Translation:
"Couldn't fetch mysqli"
You closed your connection and are trying to use it again.
It has taken me DAYS to figure out what this obscure error message means...
jcwebb at dicoe dot com ¶
15 years ago
When building apps, i like to see the whole statement when if fails.
<?php
$q="SELECT somecolumn FROM sometable"; //some instruction
$r=mysqli_query($DBlink,$q) or die(mysqli_error($DBlink)." Q=".$q);
?>
If theres an error (like my numerous typing mistakes) this shows the entire instruction.
Good for development (not so good on production servers - simply find and replace when finished: $r=mysqli_query($DBlink,$q); )
Hope it helps. Jon
joseph_robert_martinez at yahoo dot com ¶
8 years ago
For those using with replication enabled on their servers, add a mysqli_select_db() statement before any data modification queries. MySQL replication does not handle statements with db.table the same and will not replicate to the slaves if a scheme is not selected before.
Found out after days of resetting master and slaves on another site http://www.linuxquestions.org/questions/linux-server-73/mysql-5-1-not-replicating-properly-with-slave-823296/
info at ff dot net ¶
16 years ago
Calling Stored Procedures
Beeners' note/example will not work. Use mysqli_multi_query() to call a Stored Procedure. SP's have a second result-set which contains the status: 'OK' or 'ERR'. Using mysqli_query will not work, as there are multiple results.
<?php
$sQuery="CALL SomeSP('params')";
if(!mysqli_multi_query($sqlLink,$sQuery)) {
// your error handler
}
$sqlResult=mysqli_store_result($sqlLink);
if(mysqli_more_results($this->sqlLink))//Catch 'OK'/'ERR'
while(mysqli_next_result($this->sqlLink));
?>
You will have to rewrite/expand this a bit for more usability of course, but it's just an example.
ahmed dot 3abdolah at gmail dot com ¶
7 years ago
Hi, i created function that add a new table using array , i work with it on my projects ...
<?PHP
/* this function was learned from PHP.net */
function array_keys_exist(&$key,array &$array){
$keys = split("\|",$key);
foreach($keys as $key_s){
if(array_key_exists($key_s, $array)) return true;
}
return false;
}
/*and this is my function */
array_create_table(array &$array){
if(is_array($array)){
$key = "table|rows|values";
$info = "";
if(array_keys_exist($key,$array)){
if(is_array($array["rows"]) and is_array($array["values"]) ){
if(count($array["rows"]) == count($array["values"])) {
for($i=0; $i<=count($array["rows"]); $i++){
$info = $info." ".$array["rows"][$i]." ".$array["values"][$i]." NOT NULL ";
if($i < count($array["rows"])-1 ) $info = $info.",";
}
$query = "CREATE TABLE ".$this->private_tables_name.$array["table"]." ";
$query .= "( id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, ".$info." )";
return $query;
}
}
}else return "Error";
}
}
/* the use is simple */
$database = new database(); // connection to database i used mysqli ...
$array = array("table"=>"MRO", "rows"=>array("name","username") , "values" => array("VARCHAR (50) "," VARCHAR (50) ") );
$query = array_create_table($array); // convert and create the query ...
if($database->query($query)) echo "Work"; else echo "Error"; // result : work
?>
Igor ¶
13 years ago
mysqli::query() can only execute one SQL statement.
Use mysqli::multi_query() when you want to run multiple SQL statements within one query.
hunreal at gmail dot com ¶
17 years ago
Use difference collation/character for connect, result.
You can set the collation before your query.
E.g. want to set the collation to utf8_general_ci
you can send the query "SET NAMES 'utf8'" first
<?php
$mysqli=new mysqli('localhost', 'root', 'password', 'test');
$mysqli->query("SET NAMES 'utf8'");
$q=$mysqli->query("select * from test");
while($r=$q->fetch_assoc()) {
print_r($r);
}
?>
There are many variables about character settings.
By running sql command, SHOW VARIABLES LIKE 'char%';
There are some variables control the character usage.
character_set_client
character_set_connection
character_set_database
character_set_results
character_set_server
character_set_system
Also SET NAMES can repalce with one or some settings like SET character_set_results='utf8';
marcus at synchromedia dot co dot uk ¶
11 years ago
The exact type returned by a successful query is mysqli_result.
thomas dekker ¶
11 years ago
Building inserts can be annoying. This helper function inserts an array into a table, using the key names as column names:
<?php
private function store_array (&$data, $table, $mysqli)
{
$cols = implode(',', array_keys($data));
foreach (array_values($data) as $value)
{
isset($vals) ? $vals .= ',' : $vals = '';
$vals .= '\''.$this->mysql->real_escape_string($value).'\'';
}
$mysqli->real_query('INSERT INTO '.$table.' ('.$cols.') VALUES ('.$vals.')');
}
?>
Adapt it to your specific needs.
popere dot noel at yahoo dot com ¶
8 years ago
or you could just extend the class...
in my case i already had a wraper for the db so something like this was easy :
public function free($result) {
$result->free_result();
$this->link->next_result();
}
just tried it and it works like a charm ;-)
omidbahrami1990 at gmail dot com ¶
4 years ago
This Is A Secure Way To Use mysqli::query
--------------------------------------------------------
<?php
function secured_query($sql)
{
$connection = new mysqli($host,$username,$password,$name);
if ($connection->connect_error)
die("Secured");
$result=$connection->query($sql);
if($result==FALSE)
die("Secured");
$connection->close();
return $result;
}
/*
$host ---> DataBase IP Address
$username ---> DataBase Username
$password ---> DataBase Password
$name ---> DataBase Name
*/
?>
Anonymous ¶
5 years ago
I don't know is it bug or something , then first I write it here . Query SHOW with MYSQLI_USE_RESULT option don't show num_rows :
<?php
SHOW TABLES LIKE [some table], MYSQLI_USE_RESULT
num_rows // shows 0 !
?>
blinki bill, argodak at yahoo dot com ¶
9 years ago
Recently I had puzzling problem when performing DML queries, update in particular, each time a update query is called and then there are some more queries to follow this error will show on the page and go in the error_log:
"Fatal error: Exception thrown without a stack frame in Unknown on line 0"
The strange thing is that all queries go through just fine so it didn't make much sense:
$update = mysqli_query($connection, $query_string);
if(!$update){
echo 'Houston we have a problem '.mysqli_error($connection);
exit;
}
In the above example "$update" is "true", mysqli_error() is empty and of course the update operation goes through, however the nasty super cryptic error appears on the page.
What makes even less sense to me is how I fixed it - just called "mysqli_free_result" after the update query and the problem was gone, however because mysqli_free_result is not supposed to be called after DML queries (to free what, a boolean? lol) it needs to be wrapped in a try catch block:
try{
mysqli_free_result($update);
}catch (Exception $e){
//do nothing
}
So, I don't know why but it seems that when DML queries are responsible for:
"Fatal error: Exception thrown without a stack frame in Unknown on line 0"
calling "mysqli_free_result" after the query seems to be fixing the issue
andrey at php dot net ¶
16 years ago
WARNING: This function was buggy on 64bit machines till 5.0.5. Affected versions 5.0.0-5.0.4. The problem appears when a value for the third parameter is passed - this will lead to instant FALSE returned by the function. Therefore if you need to use unbuffered query don't use this function with the aforementioned versions but you mysqli_real_query() and mysqli_use_result().
If you have the rights to patch you PHP installation the fix is easy:
In file ext/mysqli/myslqi_nonapi.c, function PHP_FUNCTION(mysqli_query)
change
unsigned int resultmode=0;
to
unsigned long resultmode=0;
Thanks!
David Marcus ¶
5 years ago
If you use the default resultmode of MYSQLI_STORE_RESULT, you can call $mysqli->close() right after $mysqli->query and before you use mysqli_result. This reduces the time the connection is open, which can help if the database server has a limit on how many connections there can be.
antiriad at gmail dot com ¶
15 years ago
this is a variant of mysqli_query that returns output parameters as a rowset.
<?php
function mysqli_exec($link, $command)
{
$select = '';
$i2 = 0;
while (true)
{
$i1 = strpos($command, '@', $i2);
if ($i1 === false)
break;
$field = '';
$i2 = $i1 + 1;
while ($i2 < strlen($command) &&
($command[$i2] >= '0' && $command[$i2] <= '9') ||
($command[$i2] >= 'A' && $command[$i2] <= 'Z') ||
($command[$i2] >= 'a' && $command[$i2] <= 'z') ||
($command[$i2] == '_'))
$i2++;
$field = substr($command, $i1 + 1, $i2 - $i1 - 1);
if (strlen($select) == 0)
$select = "select @{$field} as $field";
else
$select = $select . ", @{$field} as $field";
}
if (strlen($select) > 0)
{
mysqli_query($link, $command);
return mysqli_query($link, $select);
}
else
return mysqli_query($link, $command);
}
?>
an example:
<?php
$link = mysqli_connect('localhost', 'myusr', 'mypass') or die ('Error connecting to mysql: ' . mysqli_error($link));
mysqli_select_db($link, 'clips');
$user_name = 'test';
$result = mysqli_exec($link, "call do_user_login('$user_name', @session_id, @msg)");
while ($row = mysqli_fetch_assoc($result))
{
echo "session_id : {$row['session_id']} <br>";
echo "msg : {$row['msg']} <br>";
}
?>
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