获取唯一值作为查询结果

Question

我与我的数据库有多对多的关系，所以我创建了一个sql查询，稍后我将用于搜索。 现在我想要做的是从搜索结果中获取一个唯一的值（唯一的公司名称）。

这是我的疑问：

SELECT agencies.company
    ,agencies.website_url
    ,agencies.STATUS
    ,agencies.size
    ,IndustryData.industry_id
    ,ProfessionData.profession_id
    ,SectorData.sector_id
    ,seniorityData.seniority_id
    ,ZonesData.zone_id
FROM agencies
LEFT JOIN (
    SELECT agencies_industries.agency_id
        ,agencies_industries.industry_id
    FROM agencies_industries
    ) AS IndustryData ON agencies.id = IndustryData.agency_id
LEFT JOIN (
    SELECT agencies_professions.agency_id
        ,agencies_professions.profession_id
    FROM agencies_professions
    ) AS ProfessionData ON agencies.id = ProfessionData.agency_id
LEFT JOIN (
    SELECT agencies_sectors.agency_id
        ,agencies_sectors.sector_id
    FROM agencies_sectors
    ) AS SectorData ON agencies.id = SectorData.agency_id
LEFT JOIN (
    SELECT agencies_seniorities.agency_id
        ,agencies_seniorities.seniority_id
    FROM agencies_seniorities
    ) AS SeniorityData ON agencies.id = SeniorityData.agency_id
LEFT JOIN (
    SELECT agencies_zones.agency_id
        ,agencies_zones.zone_id
    FROM agencies_zones
    ) AS ZonesData ON agencies.id = ZonesData.agency_id
WHERE IndustryData.industry_id = 3
    AND ProfessionData.profession_id = 1

结果如下：

公司，website_url，status，size，industry_id，profession_id，sector_id，seniority_id，zone_id

1. Nine nine.com 1 3 3 1 3 2 1
2. Nine nine.com 1 3 3 1 3 2 5
3. Nine nine.com 1 3 3 1 3 2 8
4. Nine nine.com 1 3 3 1 3 5 1
5. Nine nine.com 1 3 3 1 3 5 5
6. Nine nine.com 1 3 3 1 3 5 8
7. Ten ten.com 2 3 3 1 3 1 1
8. Ten ten.com 2 3 3 1 3 1 3
9. Ten ten.com 2 3 3 1 3 1 7
10. Ten ten.com 2 3 3 1 3 3 1
11. Ten ten.com 2 3 3 1 3 3 3
12. Ten ten.com 2 3 3 1 3 3 7
13. Ten ten.com 2 3 3 1 3 5 1
14. Ten ten.com 2 3 3 1 3 5 3
15. Ten ten.com 2 3 3 1 3 5 7

我想摆脱公司名称的重复。我该怎么做？

Answer 1

也许您可以使用变量和子查询来做到这一点，如下所示：

http://dev.mysql.com/doc/refman/5.0/en/user-variables.html

但也许在您的代码中执行此操作比在查询中更快。

Answer 2

您可以使用GROUP BY，例如：

SELECT agencies.company
    ,agencies.website_url
    ,agencies.STATUS
    ,agencies.size
    ,IndustryData.industry_id
    ,ProfessionData.profession_id
    ,SectorData.sector_id
FROM ...
GROUP BY agencies.company
    ,agencies.website_url
    ,agencies.STATUS
    ,agencies.size
    ,IndustryData.industry_id
    ,ProfessionData.profession_id
    ,SectorData.sector_id