如何使用UNION在mysql中选择两个表 - how can a select two tables in mysql using UNION?

how can a select two tables in mysql using UNION?

本文关键字：两个选择 UNION 何使用 mysql | 更新日期: 2024-05-26

https://drive.google.com/file/d/0ByVhijs7bMwjUUZQRHpXUHFvODg/edit?usp=sharing

这是我的代码

我无法使用UNION从两个表"香草"answers"水果"中选择product_name和price我是php和mysql的初学者请帮我

$results = $mysqli->query("SELECT * FROM fruits UNION SELECT * FROM herbs WHERE product_code='$product_code' LIMIT 1");
$obj = $results->fetch_object();

我建议您先阅读本教程。where关键字应用于每个表。像这样：

$results = $mysqli->query("SELECT * FROM fruits WHERE product_code='$product_code' UNION SELECT * FROM herbs WHERE product_code='$product_code' LIMIT 1");
$obj = $results->fetch_object();

尝试这个

$results = $mysqli->query(" 
                          SELECT * FROM fruits WHERE t.product_code='$product_code'
                           UNION 
                           SELECT * FROM herbs WHERE t.product_code='$product_code' 
                           LIMIT 1");
$obj = $results->fetch_object();