Question

我在数据库中有一个表，当前正在使用SELECT语句提取数据，其中“意见”列中的信息等于“否”或“肯定”。

我还想做的是输出正数据作为整体百分比，但是不确定是否有可能我查看了多个溢出问题，但什么也没看到。任何帮助将不胜感激。

    $sql = "select Opinion from survey where Opinion = 'Positive'";

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

    if (!$result) {
        die(mysqli_error($con)); 
    }

    echo "<div style='overflow: auto;'>";
    echo "<table width=40% border=1 align=center >
            <tr>
                <th>Opinion</th>
                <th>Date</th>
            </tr>"; 

    if (mysqli_num_rows($result) > 0) {
        while($row = mysqli_fetch_assoc($result)) {
            echo '<tr align=center>';
            echo "<td>" . $row['Opinion'] . "</td>";    
    }

} else {
    echo "0 results";
}
?>

Answer 1

该查询将计算与“调查”表的总行相比，“正面”意见的百分比：

select (SUM(IF(Opinion = 'Positive',1,0))/count(*))*100 as percentage_positive
from survey

下面的查询可以一次确定每种不同意见的百分比：

select 
    Opinion,
    count(*) as total,
    (count(*) / (select count(*) from survey))*100 as percentage
from survey  
group by opinion

Answer 2

像SQL查询这样的东西吗？

SELECT COUNT(Opinion) /  (SELECT COUNT(Opinion) FROM survey) * 100
FROM survey 
WHERE Opinion = 'Negative'

Answer 3

在Kevin HR的帮助下，我使用下面的代码解决了我的问题。

$sql = "select Opinion,count(*) as total,(count(*) / (select count(*) from survey))*100 as percentage from survey group by opinion";

$result = mysqli_query($con, $sql);
   echo "<div style='overflow: auto;'>";
echo "<table width=40% border=1 align=center >
<tr>
<th>Opinion</th>
<th>Percentage</th>
</tr>"; 

   if (mysqli_num_rows($result) > 0) {

         while($row = mysqli_fetch_assoc($result)) {

        echo '<tr align=center>';

                            echo "<td>" . $row['Opinion'] . "</td>";
                            echo "<td>" . $row['percentage'] . "</td>";
         }
   } 
    else {
    echo "0 results";
}

Answer 4

用于从数据库获取行数值的工作代码

$sql = "SELECT * FROM `survey` WHERE Opinion='Positive'";

$connStatus = $con->query($sql);

$numberOfRows = mysqli_num_rows($connStatus);

echo "There are a total number of $numberOfRows Positive rows in the database";
echo "<br>";
echo "<br>";

mysql以百分比形式获取数据库中列的值

4 个答案: