SQL SQL查询以选择每种类型之一
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SQL query to select one of each kind
提问by Bogdan Kanivets
Let's say I have this table:
假设我有这张桌子：
id colorName
1 red
2 blue
3 red
4 blue
id 颜色名称
1 红色
2 蓝色
3 红色
4 蓝色
How can I select one representative of each color?
Result:
1 red
2 blue
如何为每种颜色选择一个代表？
结果：
1红
2蓝
回答by Tony Andrews
Not random representatives, but...
不是随机代表，而是……
select color, min(id)
from mytable
group by color;
回答by user4812
select distinct colorname from mytable
回答by Quassnoi
In MS SQL Serverand Oracle:
在MS SQL Server和Oracle：
SELECT id, colorName
FROM (
SELECT id, colorName,
ROW_NUMBER() OVER (PARTITION BY colorName ORDER BY id) AS rn
FROM colors
) q
WHERE rn = 1
回答by Sony G
Here is the easiest way:
这是最简单的方法：
SELECT DISTINCT colorName FROM mytable ORDER BY colorName
回答by dkretz
Try this:
尝试这个：
SELECT colorName,
MIN(id) AS id
FROM table
GROUP BY colorname
回答by SierraJuliet
SELECT DISTINCT colorname FROM yourtable ORDER BY id; (change id to colorname if desired)
SELECT DISTINCT colorname FROM yourtable ORDER BY id; （如果需要，将 id 更改为 colorname）
or
或者
SELECT colorname FROM yourtable GROUP BY colorname;
SELECT colorname FROM yourtable GROUP BY colorname;
