Question

我有一个表单，其中的复选框将所选行发布到$ _POST ['select'] [$ i]数组中，该数组用于从db选择数据。 sql的结果用于用换行符将结果写入文本文件，但仅写入第一行，其余为空行。请帮忙。我的代码如下。

<?php 

    $rowCountd = count($_POST["select"]);
    for($i=0;$i<$rowCountd;$i++) {

        $rowwd=$_POST['select'][$i]; 

        $path_stu_test = $_SERVER['USERPROFILE'].'\Documents\performance/student_test.txt';

        $file_stu_test = fopen($path_stu_test, 'w');    

        $stmt = $db->prepare('SELECT row_no, adms_no, full_name from stu_perform where row_no= :rowwd1');

        $stmt->bindParam(':rowwd1', $postrowwd1, SQLITE3_TEXT); $postrowwd1 = $rowwd;
        $ret = $stmt->execute(); 

        while($row = $ret->fetchArray(SQLITE3_ASSOC)){

            $adms_not = $row['adms_no'];
            $full_namet = $row['full_name'];
            $file2 = "$adms_not~$full_namet\r\n";
            fwrite($file_stu_test, $file2);

        }
    }
?>

我认为问题是我在for（）循环中使用While（）{}块使用fwrite的方式，因为下面的代码有效，即它显示了写入所有sql结果的结果

<?php

    $rowwd = 02;
    $path_stu_test = $_SERVER['USERPROFILE'].'\Documents\performance/student_test.txt';

    $file_stu_test = fopen($path_stu_test, 'w');

    $stmt = $db->prepare('SELECT row_no, adms_no, full_name from stu_perform where row_no= :rowwd1');

    $stmt->bindParam(':rowwd1', $postrowwd1, SQLITE3_TEXT);
    $postrowwd1 = $rowwd;
    $ret = $stmt->execute();

    while($row = $ret->fetchArray(SQLITE3_ASSOC)){

        $adms_not = $row['adms_no'];
        $full_namet = $row['full_name'];

        $file2 = "$adms_not~$full_namet\r\n";
        fwrite($file_stu_test, $file2);

    }
?>

Answer 1

两种可能的方法-均未经过测试。我在原始代码中注意到的一件事是创建预准备语句的方式-即在循环内部。 Prepared语句的优点和优点之一是您应该创建一次，但是要执行多次〜因此，下面的第一个示例在循环外部准备查询，并在循环内部使用每次递增的数组值使用不同的值多次执行查询。

<?php 

    if( !empty( $_POST['select'] ) ){

        $bytes=array();
        $count=count( $_POST['select'] );
        $outputfile=sprintf( '%s/Documents/performance/student_test.txt', $_SERVER['USERPROFILE'] );

        $sql='select `row_no`, `adms_no`, `full_name` from `stu_perform` where `row_no`=:id;';
        $stmt=$db->prepare( $sql );

        if( $stmt ){

            $stmt->bindParam( ':id', $id, SQLITE3_TEXT );

            for( $i=0; $i < $count; $i++ ){

                $id = $_POST['select'][ $i ];
                $result = $stmt->execute();

                if( $result ){
                    while( $rs=$result->fetchArray( SQLITE3_ASSOC ) ){
                        $data = sprintf( '%s~%s', $rs['adms_no'], $rs['full_name'] );
                        $bytes[]=file_put_contents( $outputfile, $data . PHP_EOL, FILE_APPEND );
                    }
                }
            }

            if( !empty( $bytes ) ) printf( '%d entries and %s bytes written to file',count( $bytes ), array_sum( $bytes ) );

        }
    }
?>

您可以在许多数据库引擎中使用in关键字（例如select * from tbl where id in (1,2,3,99)等）来代替执行多次，

<?php 

    if( !empty( $_POST['select'] ) ){

        $bytes=array();
        $count=count( $_POST['select'] );
        $outputfile=sprintf( '%s/Documents/performance/student_test.txt', $_SERVER['USERPROFILE'] );

        $sql='select `row_no`, `adms_no`, `full_name` from `stu_perform` where `row_no` in ( :ids );';
        $stmt=$db->prepare( $sql );

        if( $stmt ){

            $stmt->bindParam( ':ids', $ids, SQLITE3_TEXT );
            $ids = implode( ',', $_POST['select'] );

            $result = $stmt->execute();

            if( $result ){
                while( $rs=$result->fetchArray( SQLITE3_ASSOC ) ){
                    $data = sprintf( '%s~%s', $rs['adms_no'], $rs['full_name'] );
                    $bytes[]=file_put_contents( $outputfile, $data . PHP_EOL, FILE_APPEND );
                }
            }


            if( !empty( $bytes ) ) printf( '%d entries and %s bytes written to file', count( $bytes ), array_sum( $bytes ) );

        }
    }
?>

作为测试以上内容的快速演示，我在阅读您的评论后将以下内容放在一起。显然，这与我的系统和数据库（mysql）有关，但严格遵循上述逻辑

<?php
    $field='select';

    if( $_SERVER['REQUEST_METHOD']=='POST' && !empty( $_POST[ $field ] ) ){
        ob_clean();

        require 'pdoconn.php';

        $file=__DIR__ . '/tmp-output.txt';
        $bytes=array();

        $sql='select * from `city` where `id`=:id';
        $stmt=$db->prepare( $sql );

        if( $stmt ){
            $stmt->bindParam( ':id', $id, PDO::PARAM_INT );
            foreach( $_POST[ $field ] as $index => $id ){
                $stmt->execute();
                while( $rs=$stmt->fetch( PDO::FETCH_OBJ ) ){
                    $bytes[]=file_put_contents( $file, sprintf( 'ID:%d, Name:%s, Country Code:%s, District: %s', $rs->ID, $rs->Name,$rs->CountryCode,$rs->District ) . PHP_EOL, FILE_APPEND );
                }
            }
        }
    }
?>
<!doctype html>
<html>
    <head>
        <meta charset='utf-8' />
        <title>multi-checkboxes - read from db, write to text file</title>
        <style>
            form{width:50%;float:none;margin:5rem auto 0 auto;}
            label{display:inline-block;margin:1rem auto;float:none;width:20%;text-align:center;border:1px dotted gray;box-sizing:border-box;}
            input[type='submit']{width:100%;padding:1rem;}
        </style>
    </head>
    <body>
        <form method='post'>
            <?php
                for( $i=1; $i <= 25; $i++ ){

                    $checked = rand(0,1) == 1 ? 'checked' : '';
                    $br = $i > 0 && $i % 5==0 ? '<br />' : '';

                    /* assume that the valud is equal to the ID of whatever record .... */
                    printf( '<label>%s<input type="checkbox" name="select[]" value="%d" %s /></label>%s', sprintf( 'Item: %d', $i ), $i, $checked, $br );
                }
                if( !empty( $bytes ) ) printf( '<p>%d entries and %s bytes written to file</p>',count( $bytes ), array_sum( $bytes ) );
            ?>
            <input type='submit' />
        </form>
    </body>
</html>

-

这显示了在提交表单之前随机选择的复选框

这显示提交表单后写入文件的数据。检查第二张图片中的ID对应于第一张图片中选中的复选框（尽管我知道您看不到它们）

为什么PHP写空行到文本文件？

1 个答案: