PHP 使用条件 if/elseif/else 创建 MySQL 查询

Question

我是 PHP 和 MySQL 的新手，正在尝试使用 php 为 MySQL 创建查询，下面是代码的当前状态，它仍然是 WIP，但是 if/elseif 结构已经给出了根据数据而变化的所需输出输入，例如可以如下

"SELECT * FROM tuntikortti WHERE PVM BETWEEN '2014-09-11' AND '2014-09-27' AND Henkilo =
 'Van' AND Tyonumero = '123456' AND Toiminto = '123';"

我已经确认查询行本身在 MySQL 中有效，但我需要以某种方式将其放入 MySQL_query($con, The query here).

那么我如何获得整个 if/elseif 查询行的 php 输出构建在变量或类似物中以供使用？

<?php
include("db_connect.php");

$pvm1       = $_POST['pvm1'];
$pvm2       = $_POST['pvm2'];
$henkilo    = $_POST['henkilo'];
$tyonumero  = $_POST['tyonumero'];
$toiminto   = $_POST['toiminto'];

/* MySQL query line build, beginning */
ECHO "SELECT * FROM tuntikortti WHERE ";

    /* PVM */
    if(!empty($pvm1) && !empty($pvm2)){
        echo "PVM BETWEEN '". $pvm1 ."' AND '". $pvm2 ."'";
    } elseif(!empty($pvm1)) {
        echo "PVM = '". $pvm1 ."'";
    };

    /* Henkilo */
    if(!empty($henkilo) && !empty($pvm1)){
        echo " AND Henkilo = '". $henkilo ."'";
    } elseif(!empty($henkilo)) {
        echo " Henkilo = '". $henkilo ."'";
    };

    /* Tyonumero */
    if(!empty($tyonumero) && (!empty($pvm1) || !empty($henkilo))){
            echo " AND Tyonumero = '". $tyonumero ."'";
        } elseif(!empty($tyonumero)) {
            echo " Tyonumero = '". $tyonumero ."'";
        };

    /* Toiminto */
    if(!empty($toiminto) && (!empty($tyonumero) || !empty($pvm1) || !empty($henkilo))){
        echo "  AND Toiminto = '". $toiminto ."'";
    } elseif(!empty($toiminto)) {
            echo " Toiminto = '". $toiminto ."'";
        };

    echo ";";

    $query = mysqli_query($sql,$con);

echo "<table border='1'>
<tr>
<th>TID</th>
<th>PVM</th>
<th>Henkilo</th>
<th>Työnumero</th>
<th>Toiminto</th>
<th>Tunnit</th>
<th>Selite</th>
</tr>";

while($row = mysqli_fetch_array($query)) {
  echo "<tr>";
  echo "<td>" . $row['TID'] . "</td>";
  echo "<td>" . $row['PVM'] . "</td>";
  echo "<td>" . $row['Henkilo'] . "</td>";
  echo "<td>" . $row['Tyonumero'] . "</td>";
  echo "<td>" . $row['Toiminto'] . "</td>";
  echo "<td>" . $row['Tunnit'] . "</td>";
  echo "<td class='selitetyyli'>" . $row['Selite'] . "</td>";
  echo "</tr>";
}

echo "</table>";

include("db_close_connection.php");
    ?>

Answer 1

检查这个例子并尝试修改你的代码，

$sql = '';
$sql = "SELECT * FROM tablename WHERE ";
if(condition){
    $sql.= "fieldname = 'value'";
} elseif(condition) {
    $sql.= "fieldname = 'value'";
};

$sql.= ";";
$query = mysqli_query($con,$sql);