sql - 无法在 Postgres 中执行联合

Question

对于某些表t，我想做以下查询：

select 'X' as "Indicator" from t limit 1
union 
select 'Y' as "Indicator" from t limit 1 

我的期望：

Indicator
X
Y

我得到什么：ERROR: syntax error at or near "union"

为什么会这样？列名相同，在这两种情况下只有一列。怎么了？

标签： sqlpostgresqlunion

Answer 1

如果你想要两个结果，就像这样

(select 'X' as "Indicator" from t limit 1)
union 
(select 'Y' as "Indicator" from t limit 1)