Question

美好的一天。

我有SQL查询：

SELECT TOP 20 
    p.id_price as p_id_price, 
    p.id_service as p_id_service, 
    p.name as p_name, 
    p.name_original as p_name_original, 
    p.id_producer_country as p_id_producer_country, 
    p.id_firm as p_id_firm, 
    f.name as f_name, 
    f.priority as f_priority, 
    f.address as f_address, 
    f.phone as f_phone, 
    city.name as city_name, 
    pc.name as pc_name 
FROM Price p 
    left join Firm f on f.id_service = p.id_service AND f.id_city = p.id_city AND f.id_firm = p.id_firm 
    left join City city on city.id_city = p.id_city left join Producer_country pc on pc.id_producer_country = p.id_producer_country 
    left join Dogovor d on d.id_service=p.id_service AND d.id_city=p.id_city AND d.id_firm=p.id_firm 
WHERE 
    id_price NOT IN ( 
        SELECT TOP 20 p.id_price 
        FROM Price p 
            left join Firm f on f.id_service = p.id_service AND f.id_city = p.id_city AND f.id_firm = p.id_firm 
            left join City city on city.id_city = p.id_city 
            left join Producer_country pc on pc.id_producer_country = p.id_producer_country 
            left join Dogovor d on d.id_service=p.id_service AND d.id_city=p.id_city AND d.id_firm=p.id_firm 
        WHERE p.id_city='73041' AND p.include='1' AND p.blocked='0' AND f.blocked='0' AND f.dogovor='1' 
                AND d.end_date >= '20131108 02:37:03' 
                AND (p.name LIKE '% tes_ %' OR p.name LIKE 'tes_ %' OR p.name LIKE '% _tes_%') 
        ORDER BY f.priority DESC 
                    ) 
AND p.id_city='73041' 
AND p.include='1' 
AND p.blocked='0' 
AND f.blocked='0' 
AND f.dogovor='1' 
AND d.end_date >= '20131108 02:37:03' 
AND (p.name LIKE '% tes_ %' OR p.name LIKE 'tes_ %' OR p.name LIKE '% _tes_%') 

ORDER BY f.priority DESC

但它查询选择并输出具有相同字段值的多行 f.name

请告诉我，如何从多行中选择一行，其中 f.name 字段的值相同？

请告诉我如何在相同的f.name中进行行号，然后选择第一个号码？

Answer 1

Group BY不一定是一个简单的概念。所以是的，请停止分享来自W3学校的链接。它更好地解释它。

如果你需要某种聚合意味着你想知道John出现了多少次，你需要在COUNT(fname)之后添加一列，然后列出每列group by选择。

如果您尝试显示最独特的值，请使用DISTINCT。因此，在SELECT添加DISTINCT之后，您将只获得每个列值唯一的行。

Answer 2

SELECT Top(20) * FROM (
SELECT  Row_Number()OVER(PARTITION BY f.name ORDER BY f.priority, p.datetime DESC) AS NameOrder, 
    p.id_price as p_id_price, 
    p.id_service as p_id_service, 
    p.name as p_name, 
    p.name_original as p_name_original, 
    p.id_producer_country as p_id_producer_country, 
    p.id_firm as p_id_firm, 
    f.name as f_name, 
    f.priority as f_priority, 
    f.address as f_address, 
    f.phone as f_phone, 
    city.name as city_name, 
    pc.name as pc_name 
FROM Price p 
    left join Firm f on f.id_service = p.id_service AND f.id_city = p.id_city AND f.id_firm = p.id_firm 
    left join City city on city.id_city = p.id_city left join Producer_country pc on pc.id_producer_country = p.id_producer_country 
    left join Dogovor d on d.id_service=p.id_service AND d.id_city=p.id_city AND d.id_firm=p.id_firm 
WHERE 
    id_price NOT IN ( 
        SELECT TOP 20 p.id_price 
        FROM Price p 
            left join Firm f on f.id_service = p.id_service AND f.id_city = p.id_city AND f.id_firm = p.id_firm 
            left join City city on city.id_city = p.id_city 
            left join Producer_country pc on pc.id_producer_country = p.id_producer_country 
            left join Dogovor d on d.id_service=p.id_service AND d.id_city=p.id_city AND d.id_firm=p.id_firm 
        WHERE p.id_city='495' AND p.include='1' AND p.blocked='0' AND f.blocked='0' AND f.dogovor='1' 
                AND d.end_date >= '20131108 02:37:03' 
                AND (p.name LIKE '% tes_ %' OR p.name LIKE 'tes_ %' OR p.name LIKE '% _tes_%') 
        ORDER BY f.priority DESC 
                    ) 
AND p.id_city='495' 
AND p.include='1' 
AND p.blocked='0' 
AND f.blocked='0' 
AND f.dogovor='1' 
AND d.end_date >= '20131108 02:37:03' 
AND (p.name LIKE '% tes_ %' OR p.name LIKE 'tes_ %' OR p.name LIKE '% _tes_%')
)
AS S WHERE S.NameOrder = 1
ORDER BY S.f_priority

如何从具有相同字段的多行中仅选择一行？

2 个答案: