Question

我正在运行命令SELECT distinct winner FROM history WHERE NOT EXISTS (SELECT * FROM players WHERE players.name = history.winner)

如果history.winner类似于“测试”（通知尾随空格）并且players.name已经具有“测试”，则似乎失败

我对于不区分大小写有同样的问题所以我将两个字段整理都设为latin1_general_cs，如果它起任何作用。我认为解决方案可能会导致使用BINARY关键字但执行

SELECT distinct BINARY winner FROM history WHERE NOT EXISTS (SELECT * FROM players WHERE BINARY players.name = history.winner)使查询非常慢（速度太慢，我在1分钟后退出）。

Answer 1

您可以使用Trim()功能来完成此任务：

SELECT DISTINCT h.winner 
FROM history h
WHERE NOT EXISTS 
(
  SELECT * 
  FROM players p  
  WHERE Trim(p.name) = Trim(h.winner)
)

Answer 2

mysql TRIM()函数将从特定字段中删除前导和尾随空格。

SELECT distinct winner FROM history WHERE NOT EXISTS (SELECT * FROM players WHERE players.name = TRIM(history.winner))

如果您只想修剪尾随空格，可以改用RTRIM()。

Relevant Documentation

如果没有EXISTS不适用于尾随空格

2 个答案: