我有一个凌乱的查询尝试找出。
我有一列称为“ meta_value”,并且其中有一些HTML数据,例如:
<tr class="child-row123"><td class="monsters">Monster</td><td class="monsters"><a data-name="Zure, Knight of Dark World">Zure, Knight of Dark World</a> x1</br><a data-name="Dark Necrofear">Dark Necrofear</a> x1</br><a data-name="Grapha, Dragon Lord of Dark World">Grapha, Dragon Lord of Dark World</a> x3</br><a data-name="Reign-Beaux, Overlord of Dark World">Reign-Beaux, Overlord of Dark World</a> x1</br><a data-name="Goldd, Wu-Lord of Dark World">Goldd, Wu-Lord of Dark World</a> x1</br><a data-name="Sillva, Warlord of Dark World">Sillva, Warlord of Dark World</a> x3</br><a data-name="Beiige, Vanguard of Dark World">Beiige, Vanguard of Dark World</a> x2</br><a data-name="Brron, Mad King of Dark World">Brron, Mad …Run Code Online (Sandbox Code Playgroud) 我有一张桌子。字段之一是类别(由枚举表示)。有些类别的商品为零。
所以我这样做:
select category, count(*) as total from items group by category;
+------------+-------+
| category | total |
+------------+-------+
| one | 6675 |
+------------+-------+
Run Code Online (Sandbox Code Playgroud)
我想生成一个这样的表(其中两个是另一个可能的枚举值):
+------------+-------+
| category | total |
+------------+-------+
| one | 6675 |
+------------+-------+
| two | 0 |
+------------+-------+
Run Code Online (Sandbox Code Playgroud)
如何使用mysql SQL查询执行此操作?