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(PHP 5)
mysqli->error -- mysqli_error — Returns a string description of the last error
Objektorientierter Stil
Prozeduraler Stil
Returns the last error message for the most recent MySQLi function call that can succeed or fail.
Nur bei prozeduralem Aufruf: Ein von mysqli_connect() oder mysqli_init() zurückgegebenes Verbindungsobjekt.
A string that describes the error. An empty string if no error occurred.
Beispiel #1 mysqli->error example
Objektorientierter Stil
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
if (!$mysqli->query("SET a=1")) {
printf("Errormessage: %s\n", $mysqli->error);
}
/* close connection */
$mysqli->close();
?>
Prozeduraler Stil
<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
if (!mysqli_query($link, "SET a=1")) {
printf("Errormessage: %s\n", mysqli_error($link));
}
/* close connection */
mysqli_close($link);
?>
The above examples will output:
Errormessage: Unknown system variable 'a'
try/catch on $mysqli->query
doesn't catch most SQL errors, you should use $mysqli->error
The decription "mysqli_error -- Returns a string description of the LAST error" is not exactly that what you get from mysqli_error. You get the error description from the last mysqli-function, not from the last mysql-error.
If you have the following situation
if (!$mysqli->query("SET a=1")) {
$mysqli->query("ROLLBACK;")
printf("Errormessage: %s\n", $mysqli->error);
}
you don't get an error-message, if the ROLLBACK-Query didn't failed, too. In order to get the right error-message you have to write:
if (!$mysqli->query("SET a=1")) {
printf("Errormessage: %s\n", $mysqli->error);
$mysqli->query("ROLLBACK;")
}
The mysqli_sql_exception class is not available to PHP 5.05
I used this code to catch errors
<?php
$query = "SELECT XXname FROM customer_table ";
$res = $mysqli->query($query);
if (!$res) {
printf("Errormessage: %s\n", $mysqli->error);
}
?>
The problem with this is that valid values for $res are: a mysqli_result object , true or false
This doesn't tell us that there has been an error with the sql used.
If you pass an update statement, false is a valid result if the update fails.
So, a better way is:
<?php
$query = "SELECT XXname FROM customer_table ";
$res = $mysqli->query($query);
if (!$mysqli->error) {
printf("Errormessage: %s\n", $mysqli->error);
}
?>
This would output something like:
Unexpected PHP error [mysqli::query() [<a href='function.query'>function.query</a>]: (42S22/1054): Unknown column 'XXname' in 'field list'] severity [E_WARNING] in [G:\database.php] line [249]
Very frustrating as I wanted to also catch the sql error and print out the stack trace.
A better way is:
<?php
mysqli_report(MYSQLI_REPORT_OFF); //Turn off irritating default messages
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
$query = "SELECT XXname FROM customer_table ";
$res = $mysqli->query($query);
if ($mysqli->error) {
try {
throw new Exception("MySQL error $mysqli->error <br> Query:<br> $query", $msqli->errno);
} catch(Exception $e ) {
echo "Error No: ".$e->getCode(). " - ". $e->getMessage() . "<br >";
echo nl2br($e->getTraceAsString());
}
}
//Do stuff with the result
?>
Prints out something like:
Error No: 1054
Unknown column 'XXname' in 'field list'
Query:
SELECT XXname FROM customer_table
#0 G:\\database.php(251): database->dbError('Unknown column ...', 1054, 'getQuery()', 'SELECT XXname F...')
#1 G:\data\WorkSites\1framework5\tests\dbtest.php(29): database->getString('SELECT XXname F...')
#2 c:\PHP\includes\simpletest\runner.php(58): testOfDB->testGetVal()
#3 c:\PHP\includes\simpletest\runner.php(96): SimpleInvoker->invoke('testGetVal')
#4 c:\PHP\includes\simpletest\runner.php(125): SimpleInvokerDecorator->invoke('testGetVal')
#5 c:\PHP\includes\simpletest\runner.php(183): SimpleErrorTrappingInvoker->invoke('testGetVal')
#6 c:\PHP\includes\simpletest\simple_test.php(90): SimpleRunner->run()
#7 c:\PHP\includes\simpletest\simple_test.php(498): SimpleTestCase->run(Object(HtmlReporter))
#8 c:\PHP\includes\simpletest\simple_test.php(500): GroupTest->run(Object(HtmlReporter))
#9 G:\all_tests.php(16): GroupTest->run(Object(HtmlReporter))
This will actually print out the error, a stack trace and the offending sql statement. Much more helpful when the sql statement is generated somewhere else in the code.
Hi, you can also use the new mysqli_sql_exception to catch sql errors.
Example:
<?php
//set up $mysqli_instance here..
$Select = "SELECT xyz FROM mytable ";
try {
$res = $mysqli_instance->query($Select);
}catch (mysqli_sql_exception $e) {
print "Error Code <br>".$e->getCode();
print "Error Message <br>".$e->getMessage();
print "Strack Trace <br>".nl2br($e->getTraceAsString());
}
?>
Will print out something like
Error Code: 0
Error Message
No index used in query/prepared statement select sess_value from frame_sessions where sess_name = '5b85upjqkitjsostvs6g9rkul1'
Strack Trace:
#0 G:\classfiles\lib5\database.php(214): mysqli->query('select sess_val...')
#1 G:\classfiles\lib5\Session.php(52): database->getString('select sess_val...')
#2 [internal function]: sess_read('5b85upjqkitjsos...')
#3 G:\classfiles\includes.php(50): session_start()
#4 G:\tests\all_tests.php(4): include('G:\data\WorkSit...')
#5 {main}
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