mysqli_free_result()函数释放结果内存。
定义和用法
一个PHP结果对象（mysqli_result类）表示由SELECT或DESCRIBE或EXPLAIN查询返回的MySQL结果。
mysqli_free_result()函数接受一个结果对象作为参数，并释放与它相关联的内存。
语法
mysqli_free_result($result);
参数
| 序号 | 参数及说明 |
|---|---|
| 1 | result(必需) 这是表示结果对象的标识符。 |
返回值
此函数不返回任何值。
PHP版本
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。
在线示例
以下示例演示了mysqli_free_result()函数的用法（面向过程风格），从结果集中获取行，然后释放结果集内存：
<?php
$con = mysqli_connect("localhost", "root", "password", "mydb");
mysqli_query($con, "CREATE TABLE myplayers(ID INT, First_Name VARCHAR(255), Last_Name VARCHAR(255), Place_Of_Birth VARCHAR(255), Country VARCHAR(255))");
print("创建表.....\n");
mysqli_query($con, "INSERT INTO myplayers values(1, 'Sikhar', 'Dhawan', 'Delhi', 'India')");
mysqli_query($con, "INSERT INTO myplayers values(2, 'Jonathan', 'Trott', 'CapeTown', 'SouthAfrica')");
mysqli_query($con, "INSERT INTO myplayers values(3, 'Kumara', 'Sangakkara', 'Matale', 'Srilanka')");
print("插入记录.....\n");
//检索表的内容
$res = mysqli_query($con, "SELECT * FROM myplayers");
print("Contents of the resultset...\n");
//结果集的内容
while ($row = mysqli_fetch_row($res)) {
print("ID: ".$row[0]."\n");
print("First_Name: ".$row[1]."\n");
print("Last_Name: ".$row[2]."\n");
print("Place_Of_Birth: ".$row[3]."\n");
print("Country: ".$row[4]."\n");
}
//结束语句，释放内存
mysqli_free_result($res);
//关闭连接
mysqli_close($con);
?>输出结果
创建表..... 插入记录..... Contents of the resultset... ID: 1 First_Name: Sikhar Last_Name: Dhawan Place_Of_Birth: Delhi Country: India ID: 2 First_Name: Jonathan Last_Name: Trott Place_Of_Birth: CapeTown Country: SouthAfrica ID: 3 First_Name: Kumara Last_Name: Sangakkara Place_Of_Birth: Matale Country: Srilanka
如果您尝试在将结果释放为后获取结果的内容-
$con = mysqli_connect("localhost", "root", "password", "mydb");
mysqli_query($con, "CREATE TABLE myplayers(ID INT, First_Name VARCHAR(255), Last_Name VARCHAR(255), Place_Of_Birth VARCHAR(255), Country VARCHAR(255))");
print("创建表.....\n");
mysqli_query($con, "INSERT INTO myplayers values(1, 'Sikhar', 'Dhawan', 'Delhi', 'India')");
mysqli_query($con, "INSERT INTO myplayers values(2, 'Jonathan', 'Trott', 'CapeTown', 'SouthAfrica')");
mysqli_query($con, "INSERT INTO myplayers values(3, 'Kumara', 'Sangakkara', 'Matale', 'Srilanka')");
print("插入记录.....\n");
//检索表的内容
$res = mysqli_query($con, "SELECT * FROM myplayers");
//结束语句
mysqli_free_result($res);
print("结果集的内容...\n");
//结果集的内容
while ($row = mysqli_fetch_row($res)) {
print("ID: ".$row[0]."\n");
print("First_Name: ".$row[1]."\n");
print("Last_Name: ".$row[2]."\n");
print("Place_Of_Birth: ".$row[3]."\n");
print("Country: ".$row[4]."\n");
}
//关闭连接
mysqli_close($con);您将收到如下所示的错误
创建表..... 插入记录..... 结果集的内容... PHP Warning: mysqli_fetch_row(): Couldn't fetch mysqli_result in E:\PHPExamples\procedure_oriented.php on line 19 Warning: mysqli_fetch_row(): Couldn't fetch mysqli_result in E:\PHPExamples\procedure_oriented.php on line 19
在线示例
在面向对象风格中，此函数的语法为$ result-> close();。以下是面向对象风格中此函数的示例；
<?php
//建立连接
$con = new mysqli("localhost", "root", "password", "mydb");
$con -> query("CREATE TABLE Test(Name VARCHAR(255), AGE INT)");
$con -> query("insert into Test values('Raju', 25),('Rahman', 30),('Sarmista', 27)");
print("创建表.....\n");
$stmt = $con -> prepare( "SELECT * FROM Test WHERE Name in(?, ?)");
$stmt -> bind_param("ss", $name1, $name2);
$name1 = 'Raju';
$name2 = 'Rahman';
//执行语句
$stmt->execute();
//检索结果
$result = $stmt->get_result();
//行数
$count = $result->num_rows;
print("结果中的行数: ".$count);
//Closing the result
$result->close();
//结束语句
$stmt->close();
//关闭连接
$con->close();
?>输出结果
创建表..... 结果中的行数: 2