多個查詢MySQL PHP

Question

是否有適當的方法來做到這一點。 我想計算一張桌子的平均評分，並同時更新另一張桌子的結果。 我是PHP和MYSQL的新手，我將不勝感激

$query=mysql_query("INSERT INTO review (username, restaurant, rating, review) VALUES ('$username','$restaurant','$rating','$review')");
if($query)
{
    $avg_query="SELECT ROUND(AVG(rating),0) FROM review WHERE name =\"$restaurant\"";
    $avg_result=mysql_query($avg_query);
    $avg_row=mysql_fetch_array($avg_result);
    $rating=$row['ROUND(AVG(rating),0)'];
    if($avg_result)
    {   
        $update_query= "UPDATE restaurant SET rating=\"$rating\" WHERE name =\"$restaurant\"";
        $update_result=mysql_query($update_query);
    }
}
else
{
}

謝謝！

Answer 1

UPDATE restaurant 
SET rating= (SELECT ROUND(AVG(rating),0) FROM review WHERE name ='$restaurant')
WHERE name ='$restaurant'

Answer 2

我將兩者結合成這樣：

$query=mysql_query("INSERT INTO review (username, restaurant, rating, review) VALUES ('$username','$restaurant','$rating','$review')");
if($query)
{
    $avg_query="UPDATE restaurant a SET rating=(SELECT ROUND(AVG(rating),0) FROM review WHERE name =a.name) WHERE name ='".$restaurant."'";
    $avg_result=mysql_query($avg_query);
}
else
{
}

話雖如此，您應該移至PDO或mysqli，因為mysql_*函數已mysql_* 。

Answer 3

另一種選擇是使用mysql trigger 。 例如（不要拘泥於語法）：

CREATE TRIGGER after_insert_review
AFTER INSERT ON review
FOR EACH ROW
BEGIN
    UPDATE restaurant 
    SET rating = (SELECT ROUND(AVG(rating),0) FROM review WHERE name = NEW.restaurant)
    WHERE name = NEW.restaurant;
END

正如其他人所提到的，再次使用PDO或MySQLi 。