MySQL，计算表中“填充”字段的数量。

Question

MySQL (表)：

+----+------+
| id | text |
+----+------+
| 1  |      |
+----+------+
| 2  | blah |
+----+------+
| 3  |      |
+----+------+
| 4  | blah |
+----+------+
| 5  | blah |
+----+------+

PHP：

$a = mysql_query("SELECT COUNT(*) AS count1 FROM `table`");
$b = mysql_fetch_assoc($a);

echo $b['count1'];

输出：

5

但是，如果可能的话，我也希望计算文本字段，这些字段是填充的--在同一个查询中。

结果：

5 in total
3 with filled text fields

Answer 1

SELECT COUNT(*) AS `total`, SUM(IF(`text` <> "",1,0)) AS `non_empty` FROM `table`

Answer 2

这可以通过子查询很好地完成。

SELECT COUNT(id) AS id, COUNT(SELECT text FROM 'table' WHERE text IS NOT NULL) AS t FROM 'table'

给自己的注意:在提交之前开始校对你的作品。