mysqli_get_warnings()函数返回上一次执行的查询所产生的错误。
如果您的最后一个MySQLi函数调用执行MySQL查询，并且它生成任何错误。mysqli_get_warnings()函数以数组的形式返回上一次执行的查询所生成的错误。
mysqli_get_warnings($con)
| 序号 | 参数及说明 |
|---|---|
| 1 | con(必需) 这是一个表示与MySQL Server的连接的对象。 |
PHP mysqli_get_warnings()函数返回一个数组，其中包含上一次查询执行期间生成的警告。
此函数最初是在PHP版本5中引入的，并且可以在所有更高版本中使用。
假设我们创建了一个名为Emp的表，如下所示：
CREATE TABLE EMP( ID TINYINT, First_Name VARCHAR(50) Not NULL, Last_Name VARCHAR(10) Not NULL, Date_Of_Birth date, Salary Int(255) );
以下示例演示了mysqli_get_warnings()函数的用法（面向过程风格）-
<?php
//建立连接
$con = mysqli_connect("localhost", "root", "password", "mydb");
//插入记录到 employee 表中
$sql = "INSERT IGNORE into emp values(1, 'Sanjay', NULL, DATE('1981-12-05'), 2566)";
mysqli_query($con, $sql);
//Warnings
$warnings = mysqli_get_warnings($con);
print("Warning(s): "."\n");
print_r($warnings);
$sql = "INSERT IGNORE into emp values (15, 'Swetha', 'Yellapragada', DATE('1990-11-25'), 9986), (15, NULL, 'Prayaga', DATE('1990-11-25'), 9986)";
mysqli_query($con, $sql);
//Warnings
$warnings = mysqli_get_warnings($con);
print("\n"."Warning(s): ");
print_r($warnings);
//关闭连接
mysqli_close($con);
?>输出结果
Warning(s): mysqli_warning Object ( [message] => Column 'Last_Name' cannot be null [sqlstate] => HY000 [errno] => 1048 ) Warning(s): mysqli_warning Object ( [message] => Data truncated for column 'Last_Name' at row 1 [sqlstate] => HY000 [errno] => 1265 )
以下是函数mysqli_get_warnings()的另一个示例-
<?php
//建立连接
$con = mysqli_connect("localhost", "root", "password", "mydb");
//删除未知表
mysqli_query($con, "drop table if exists WrongTable");
print("\n"."Warning(s): "."\n");
print_r(mysqli_get_warnings($con));
//关闭连接
mysqli_close($con);
?>输出结果
Warning(s): mysqli_warning Object ( [message] => Unknown table 'mydb.wrongtable' [sqlstate] => HY000 [errno] => 1051 )
您也可以使用mysqli_warning类的next()函数一个接一个地检索警告，如下所示：
<?php
//建立连接
$con = new mysqli("localhost", "root", "password", "mydb");
//插入记录到 employee 表中
$con -> query("INSERT IGNORE into emp values(105, NULL, 'Yellapragada', DATE('1981-12-05'), 2566)");
if($con->warning_count){
$w = mysqli_get_warnings($con);
do {
echo "Warning: $w->errno: $w->message\n";
} while ($w->next());
}
//关闭连接
$con -> close();
?>输出结果
Warning: 1048: Column 'First_Name' cannot be null Warning: 1265: Data truncated for column 'Last_Name' at row 1
返回上一次执行的查询所产生的错误
<?php
$servername = "localhost";
$username = "root";
$password = "password";
$dbname = "mydb";
$conn = new mysqli($servername, $username, $password, $dbname);
if (!$conn->real_connect($servername, $username, $password, $dbname)) {
die('Connect Error (' . mysqli_connect_errno() . ') '. mysqli_connect_error());
}
print("数据库已连接" ."\n");
mysqli_query($conn, "CREATE TABLE sample (ID INT, Name VARCHAR(20))");
$query = "INSERT IGNORE INTO sample (id,name) VALUES(
1,'Rajesh Ramayan Kootrapally')";
mysqli_query($conn, $query);
$count = mysqli_warning_count($conn);
print("No.Of warnings in the query:".$count."\n");
if ($count) {
$warnings = mysqli_get_warnings($conn);
print_r($warnings);
}
mysqli_close($conn);
?>输出结果
数据库已连接 No.Of warnings in the query:1 mysqli_warning Object ( [message] => Data truncated for column 'Name' at row 1 [sqlstate] => HY000 [errno] => 1265 )