mysqli_fetch_array（）期望参数1为mysqli_result-需要帮助

Question

mysqli_fetch_array()期望参数1为mysqli_result，布尔值为-

$query = "SELECT type, SUM(price) FROM products GROUP BY type";

$result=mysqli_query($db, $query);


while($row = mysqli_fetch_array($result)){
    echo "Total ". $row['type']. " = $". $row['SUM(price)'];

}

Answer 1

首先，检查$db标识符，在哪里定义连接？如果连接正常，则需要使用mysqli_error()

检查查询错误

您应该检查$result参数：

$query = "SELECT type, SUM(price) FROM products GROUP BY type";

$result=mysqli_query($db, $query);

if($result === FALSE) { 
    printf("Error: %s\n", mysqli_error($db)); // TODO: better error handling
}    

while($row = mysqli_fetch_array($result)){
    echo "Total ". $row['type']. " = $". $row['SUM(price)'];

}

Answer 2

使用“为”：

$query = "SELECT type, SUM(price) as sums FROM products GROUP BY type";
$result=mysqli_query($db, $query);
while($row = mysqli_fetch_array($result))
{
echo "Total ". $row['type']. " = $". $row['sums'];
}