Flinksql bug :Illegal mixing of types in CASE or COALESCE statement

报错信息

org.apache.flink.table.api.ValidationException: SQL validation failed. From line 66, column 23 to line 68, column 46: Illegal mixing of types in CASE or COALESCE statement

org.apache.calcite.runtime.CalciteContextException: From line 66, column 23 to line 68, column 46: Illegal mixing of types in CASE or COALESCE statement

org.apache.calcite.sql.validate.SqlValidatorException: Illegal mixing of types in CASE or COALESCE statement

发生地址

flinksql中的 COALESCE 函数 或 case 函数

报错原因：

case when 多条判断语句 输出数据类型不一致

实例 ：

case when id = 1 then 1
when id = 2 then '2'
end

解决方案：

统一数据类型即可

case when id = 1 then 1
when id = 2 then case('2' as int )
end