Question

如何计算特定单词出现的行数，并显示包含所有结果的表格。现在只是得到一个空白页面。

$conn = new mysqli($servername, $username, $password, $dbname);

// Set BoatName as variable from the table containing list of boats.

$query = "SELECT BoatName from SpeciesHuntBoats";
$boatname = $conn->query($query);

// Calculate number of rows that boat name appears in another table

$result = mysqli_query($conn, "SELECT * FROM SpeciesHunt WHERE `BoatName` = '$boatname'");
$num_rows = mysqli_num_rows($result);


// Display a table showing all boat names and the number of rows that name appears in 

echo "<table><tr><th>Boat Name</th><th>Number of Species</th></tr>";
while($row = $result->fetch_assoc()) {
    echo "<tr><td>" . $row["BoatName"] . "</a></td><td>" . $row["$num_rows"]. "</td>/tr>";
}

echo "</table>";
$conn->close();

Answer 1

1：如果您有错误，请始终检查服务器的错误日志。这将告诉你确切的答案。

2：query返回一个mysql_result，你需要进一步处理它。 $boatname = $conn->query($query);为变量分配一个mysql_result对象 "SELECT * FROM SpeciesHunt WHERE BoatName = '$boatname'"会尝试将其转换为字符串，但会在php中抛出错误。可能这是你的问题。

试试$boatname = $conn->query($query)->fetch_object()->BoatName。这会将查询结果提取到一个对象数组中，然后选择第0个索引，然后获取元素BoatName。

顺便说一句，我不知道你的目标，但我提供的代码将从第一行获得船名。如果有多个BoatName并且您想要处理它们中的每一个，则需要将其置于循环中。或者，您可以使用以下查询，然后将结果放入表

SELECT 
    COUNT(SpeciesHunt.id) AS NumberOfSpecies, 
SpeciesHuntBoats.BoatName
FROM SpeciesHunt
LEFT JOIN SpeciesHuntBoats 
    ON SpeciesHuntBoats.BoatName = SpeciesHunt.BoatName
GROUP BY SpeciesHunt.BoatName;

然后打印到表格：

echo "<table><tr><th>Boat Name</th><th>Number of Species</th></tr>";
while($row = $result->fetch_assoc()) {
    echo "<tr><td>" . $row["BoatName"] . "</a></td><td>" . $row["NumberOfSpecies"]. "</td>/tr>";
}

echo "</table>";

计算变量出现的行数

1 个答案: