sql - Oracle SQL CASE WHEN ORA-00932 : inconsistent datatypes: expected CHAR got NUMBER 00932. 00000 - "inconsistent datatypes: expected %s got %s"

Question

获取错误
ORA-00932: inconsistent datatypes: expected CHAR got NUMBER 00932. 00000 - "inconsistent datatypes: expected %s got %s"
当我运行以下查询时

SELECT distinct 
CASE when t.cancelled = 'TRUE' then '0' 
else t.amount END AMOUNT,
FROM table t

如果我为 else 输出使用数字或文本运行它，就像这样，它可以工作。

SELECT distinct 
CASE when t.cancelled = 'TRUE' then '0' 
else 'xxx' END AMOUNT,
FROM table t

Answer 1

使用 0而不是 '0' .金额是一个数字，数字没有被引用。

SELECT distinct 
CASE when t.cancelled = 'TRUE' then 0 
else t.amount END AMOUNT,
FROM table t