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fangzhzh 2013-07-09 16:55:30 +08:00
可不可以不要select *, 表结构一变,你这代码就随时可能爆炸啊
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iloveyou OP |
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fangzhzh 2013-07-09 16:59:25 +08:00
除了select*不能接受, 你这写法我能接受
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sutar 2013-07-09 17:01:24 +08:00
JOIN
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lichao 2013-07-09 17:06:25 +08:00
select category.field1, item.field2 from category, item where item.categoryID = category.categoryID
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lichao 2013-07-09 17:15:39 +08:00 ![]() select category.categoryName, count(item.itemID) as YOUR_COUNT from category, item where item.categoryID = category.categoryID group by category.categoryID
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lichao 2013-07-09 17:16:13 +08:00 ![]() select category.categoryID, count(item.itemID) as YOUR_COUNT from category, item where item.categoryID = category.categoryID group by category.categoryID
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cdfmr 2013-07-09 17:19:35 +08:00 ![]() select category, count(*) from item group by category,将此临时表与category表做联合查询。
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msg7086 2013-07-09 18:37:24 +08:00
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master 2013-07-09 20:08:18 +08:00
话说为什么不用JOIN ?
比如像这样: SELECT category.*, COUNT(item.id) as item_count FROM category LEFT JOIN item ON item.category = category.id |
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master 2013-07-09 20:09:17 +08:00 ![]() 抱歉,漏了 GROUP
SELECT category.*, COUNT(item.id) as item_count FROM category LEFT JOIN item ON item.category = category.id GROUP BY category.id |