php - 如何将 MySQL 定义的名称导入 php？

Question

如果我有一个像这样的mysql查询

(SELECT COUNT(*) FROM data AS amount)
UNION
(SELECT COUNT(*) FROM data WHERE some < 50 AS something)

然后像这样用 php 创建一个数组 $row = mysqli_fetch_array($sql, MYSQLI_ASSOC);。

我现在如何解决每个 AS 名称。这不起作用:echo $row["amount"];。我的第二个问题是为什么在有 WHERE 子句时我不能使用 AS something？

Answer 1

试试这个:

(
  SELECT 
    'amount1' as za_name, 
    COUNT(*) as za_count 
  FROM 
    data
) 
UNION 
(
  SELECT 
    'amount2' as za_name, 
    COUNT(*) as za_count 
  FROM 
    data 
  WHERE some < 50 
)

然后可以通过$row[za_name]进行区分，得到金额$row[za_count]

对于第二个问题:如果你做一个临时表就可以使用它:

SELECT
  tmp.za_name,
  tmp.za_count
FROM (
  SELECT 
    'amount2' as za_name, 
    COUNT(*) as za_count 
  FROM 
    data 
  WHERE some < 50 
) as tmp