Question

我有一个像这样的SQL查询：

SELECT 
u.id,
tu.score/(CASE tu.mo_count  WHEN 0 THEN NULL ELSE tu.mo_count END) AS score_avg
FROM tournament_userscore tu
INNER JOIN users u ON u.id = tu.user_id
WHERE tournament_id = 1
ORDER BY tu.score DESC

当tu.mo_count为零时，Null已被替换而不是零。如何为此行设置'EMPTY'之类的字符串：

tu.score/(CASE tu.mo_count  WHEN 0 THEN NULL ELSE tu.mo_count END) AS score_avg

我的意思是当分割结果为零或为空时，我想返回“任何内容“string。

Answer 1

如果您不想使用CASE，可以使用NULLIF和COALESCE：

SELECT 
  u.id,
  COALESCE(tu.score/NULLIF(tu.mo_count, 0), 0) AS score_avg
FROM tournament_userscore tu
  INNER JOIN users u ON u.id = tu.user_id
WHERE 
  tournament_id = 1
ORDER BY 
  tu.score DESC;

Answer 2

尝试将CASE - 语句移到外面：

SELECT 
u.id,
CASE WHEN tu.mo_count = 0 THEN 'EMPTY' ELSE (tu.score/tu.mo_count)::text END as score_avg
FROM tournament_userscore tu
INNER JOIN users u ON u.id = tu.user_id
WHERE tournament_id = 1
ORDER BY tu.score DESC

除法结果为零时返回字符串

2 个答案: