mysqli_free_result()函数释放结果内存。
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。
mysqli_free_result($result);
序号 | 参数及说明 |
---|---|
1 | result(必需) 这是表示结果对象的标识符。 |
此函数不返回任何值。
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。
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