mySQL ORDER BY 临时计算列

Question

首先你必须知道:我有两个表“USERS”和“SONGS”

如何检查某些条件并将结果放在临时列上？例如，选择结果中的每首歌曲必须计算 bool 值并将其添加到临时列，这样我就可以进行其他计算并将其设为主要顺序......

$USER = SELECT * FROM USERS WHERE SOMECONDITION

SELECT * FROM SONGS
------
(
IF SONGS.LANG  LIKE $USER[LANG]  THEN TEMPCOLUMN.ADD "1" ELSE TEMPCOLUMN.ADD 0
IF SONGS.GENR1 LIKE $USER[GENR1] THEN TEMPCOLUMN.ADD "1" ELSE TEMPCOLUMN.ADD 0
IF SONGS.GENR2 LIKE $USER[GENR2] THEN TEMPCOLUMN.ADD "1" ELSE TEMPCOLUMN.ADD 0
)
------
ORDER BY TEMPCOLUMN DESC

Answer 1

这应该做同样的事情:

SELECT * FROM SONGS
ORDER BY
  SONGS.LANG LIKE $USER[LANG] DESC,
  IF SONGS.GENR1 LIKE $USER[GENR1] DESC,
  IF SONGS.GENR2 LIKE $USER[GENR2] DESC;