关于CASE WHEN查询的MySQL帮助

Question

我不确定什么是错误，我想在SQL查询中使用499，Country在哪里说Test，以便放置Test的所有其他内容，但它给出了所有结果词499，我不明白为什么，在结果中我看到SELECT SQL_NO_CACHE id, drzavljanstvo, ( CASE WHEN drzavljanstvo=( SELECT id_drzavljanstvo from drzavljanstvo WHERE id_drzavljanstvo=499) THEN 'Country' ELSE 'Test' END) location FROM bol_rac; ？有人能帮助我吗？

#first convert `subject_id` to int
df_a['subject_id'] = df_a['subject_id'].astype(int)
m1 = (df_a['subject_id'] == 2) & (df_a['first_name'] == 'Amy')
m2 = (df_a['subject_id'] > 0) & (df_a['first_name'] == 'Alice')

df_a['outcome'] = np.select([m1, m2], [2,1], default=0)
print (df_a)
   subject_id first_name last_name  outcome
0           1       Alex  Anderson        0
1           2        Amy  Ackerman        2
2           3      Allen       Ali        0
3           4      Alice      Aoni        1
4           5     Ayoung   Atiches        0

结果如下所示