[英]Sum of all the numbers in a column for 3 tables?
我正在尝试使用PHP和SQL来回显3个单独表中的列总和。 我想知道如何简化它,因为它很肿。
谢谢!
public function getTotalSum() {
include("dbconnect.php");
$query1 = "SELECT SUM(column1) AS 'count' FROM table1";
$query2 = "SELECT SUM(column2) AS 'count' FROM table2";
$query3 = "SELECT SUM(column3) AS 'count' FROM table3";
$result1 = mysqli_query($sqlcon, $query1);
$result2 = mysqli_query($sqlcon, $query2);
$result3 = mysqli_query($sqlcon, $query3);
if (mysqli_num_rows($result1) > 0 && mysqli_num_rows($result2) > 0 && mysqli_num_rows($result3) > 0) {
while ($row = $result1->fetch_assoc() + $result2->fetch_assoc() + $result3->fetch_assoc()) {
echo $row['count'];
}
}
}
使用一个sql查询而不是多个sql查询。
应用以下方法:
public function getTotalSum() {
include("dbconnect.php");
$query = "SELECT
(SELECT SUM(column1) AS 'count' FROM table1)
+ (SELECT SUM(column2) AS 'count' FROM table2)
+ (SELECT SUM(column3) AS 'count' FROM table3) AS count;
";
$result = mysqli_query($sqlcon, $query);
if (mysqli_num_rows($result) > 0) {
$row = $result->fetch_assoc();
echo $row['count'];
}
}
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