如何使用 COALESCE 函数将 NULL 值替换为字符串？

Question

尝试使用 select 语句中的 coalesce 函数将“未分配”设置为空值。 代码如下：

SELECT ORDER_ID, ORDER_DATE,
coalesce (SALES_REP_ID,'NA') REP
FROM ORDERS```
[But having error "inconsistent datatype"]
How do I fix it?

[Data, in which sales_rep_id have null values which i want to change it to 'unassigned']

Answer 1

您需要确保不混合数据类型

SELECT ORDER_ID, ORDER_DATE,
       case when SALES_REP_ID is null 
            then 'NA'
            else to_char(SALES_REP_ID)
       end REP
FROM ORDERS