Question

大家好，我一直在尝试这个sql搜索查询到我的网站搜索工具，它应该按相关性搜索和排序。它没有左连接工作，我无法使用左连接。这是SQL查询。

SELECT bl_albums.*, bl_bands.name as bandname, bl_bands.id as bandid, 
       bl_bands.bandpage as bandpage, sum(relevance)
FROM bl_albums 
LEFT JOIN(
  SELECT  bl_albums.*, bl_bands.name as bandname, bl_bands.id as bandid, 
          bl_bands.bandpage as bandpage,10 AS relevance 
  FROM bl_albums 
  WHERE bl_albums.name like 'Camera'
  UNION
  SELECT bl_albums.*, bl_bands.name as bandname, bl_bands.id as bandid, 
         bl_bands.bandpage as bandpage, 7 AS relevance 
  FROM bl_albums 
  WHERE bl_albums.name like 'Camera%'
  UNION
  SELECT  bl_albums.*, bl_bands.name as bandname, bl_bands.id as bandid, 
          bl_bands.bandpage as bandpage, 5 AS relevance 
  FROM bl_albums 
  WHERE bl_albums.name like '%Camera'
  UNION
  SELECT bl_albums.*, bl_bands.name as bandname, bl_bands.id as bandid, 
         bl_bands.bandpage as bandpage, 2 AS relevance 
  FROM bl_albums 
  WHERE bl_albums.name like '%Camera%'
)  bl_bands on bl_albums.bandid = bl_bands.id
GROUP BY bl_albums.name
ORDER BY relevance desc

所有表名都正确，所有列名都正确。

Answer 1

您命名为'bl_bands'的子查询没有bl_bands.id，因为所有联合连接都不包含bl_bands表。如果我对所有数据的假设是正确的，请尝试向每个联合添加联接：

SELECT
    bl_albums.*,
    bl_bands.name as bandname,
    bl_bands.id as bandid, 
    bl_bands.bandpage as bandpage,
    sum(relevance)
FROM
    bl_albums 
    LEFT JOIN(
      SELECT  bl_albums.*, bl_bands.name as bandname, bl_bands.id as bandid, 
              bl_bands.bandpage as bandpage,10 AS relevance 
      FROM bl_albums
        JOIN bl_bands ON bl_bands.id = bl_albums.bandid 
      WHERE bl_albums.name like 'Camera'
      UNION
      SELECT bl_albums.*, bl_bands.name as bandname, bl_bands.id as bandid, 
             bl_bands.bandpage as bandpage, 7 AS relevance 
      FROM bl_albums 
        JOIN bl_bands ON bl_bands.id = bl_albums.bandid
      WHERE bl_albums.name like 'Camera%'
      UNION
      SELECT  bl_albums.*, bl_bands.name as bandname, bl_bands.id as bandid, 
              bl_bands.bandpage as bandpage, 5 AS relevance 
      FROM bl_albums 
        JOIN bl_bands ON bl_bands.id = bl_albums.bandid
      WHERE bl_albums.name like '%Camera'
      UNION
      SELECT bl_albums.*, bl_bands.name as bandname, bl_bands.id as bandid, 
             bl_bands.bandpage as bandpage, 2 AS relevance 
      FROM bl_albums 
        JOIN bl_bands ON bl_bands.id = bl_albums.bandid
      WHERE bl_albums.name like '%Camera%'
    ) bl_bands ON bl_albums.bandid = bl_bands.id
GROUP BY bl_albums.name
ORDER BY relevance desc

看起来你可能已经复制/粘贴了一些SELECT语句/列名，但没有添加你需要获得结果的连接。

Answer 2

我不相信这个查询有效。内部查询毫无意义。例如

SELECT  bl_albums.*, bl_bands.name as bandname, bl_bands.id as bandid, 
      bl_bands.bandpage as bandpage,10 AS relevance 
FROM bl_albums 
WHERE bl_albums.name like 'Camera'

此查询包含许多使用bl_bands预先修复的字段，但该表未包含在from语句或连接中。

使用UNION和LEFT JOIN进行选择

2 个答案: