如何在 PostgreSQL 中将 int 转换为 string

Question

我有这个：COALESCE(amount ,0) as amount。的数据类型amount是numeric.

而不是0我想要的N/A。我怎样才能做到这一点？我收到错误：

ERROR:  invalid input syntax for type numeric: "N/A"

Answer 1

使用类型转换：

coalesce(CAST(amount AS text), 'N/A')

Answer 2

在你的情况下更适合这个代码：coalesce(cast(nullif(amount, 0) as text), 'N/A')

还有关于节省的补充：

case 
  when coalesce(cast(nullif(a.amount1, 0) as text), 'N/A') = 'N/A' then 'N/A' 
  when coalesce(cast(nullif(a.amount2, 0) as text), 'N/A') = 'N/A' then 'N/A'  
  else (coalesce(cast(nullif(a.amount1 - a.amount2, 0) as text), 'N/A')) 
end as savings