Amazon Redshift中日期字段不为空的情况

Question

Select CASE 
          WHEN eventdate IS NOT NULL
          then 1 
          ELSE 0 
       end as datestatus
FROM table

我正在AWS Redshift表上运行，但出现以下错误：

[Amazon](500310) Invalid operation: COALESCE types character varying and integer cannot be matched;
1 statement failed.