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https://issues.apache.org/jira/browse/FLINK-31003?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17686862#comment-17686862
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weiqinpan commented on FLINK-31003:
-----------------------------------
Only find this in Flink 1.15.0 +, everything is right before 1.15.0.
> Flink SQL IF / CASE WHEN Funcation incorrect
> --------------------------------------------
>
> Key: FLINK-31003
> URL: https://issues.apache.org/jira/browse/FLINK-31003
> Project: Flink
> Issue Type: Bug
> Components: Table SQL / API
> Affects Versions: 1.15.0, 1.15.1, 1.16.0, 1.15.2, 1.15.3, 1.16.1
> Reporter: weiqinpan
> Priority: Major
>
> When I execute the below sql using sql-client，i found something wrong.
>
> {code:java}
> CREATE TEMPORARY TABLE source (
> mktgmsg_biz_type STRING,
> marketing_flow_id STRING,
> mktgmsg_campaign_id STRING
> )
> WITH
> (
> 'connector' = 'filesystem',
> 'path' = 'file:///Users/xxx/Desktop/demo.json',
> 'format' = 'json'
> );
> -- return correct value('marketing_flow_id')
> SELECT IF(`marketing_flow_id` IS NOT NULL, `marketing_flow_id`, '') FROM
> source;
> -- return incorrect value('')
> SELECT IF(`marketing_flow_id` IS NULL, '', `marketing_flow_id`) FROM
> source;{code}
> The demo.json data is
>
> {code:java}
> {"mktgmsg_biz_type": "marketing_flow", "marketing_flow_id":
> "marketing_flow_id", "mktgmsg_campaign_id": "mktgmsg_campaign_id"} {code}
>
>
> BTW, use case when + if / ifnull also have something wrong.
>
> {code:java}
> -- return wrong value(''), expect return marketing_flow_id
> select CASE
> WHEN `mktgmsg_biz_type` = 'marketing_flow' THEN IF(`marketing_flow_id`
> IS NULL, `marketing_flow_id`, '')
> WHEN `mktgmsg_biz_type` = 'mktgmsg_campaign' THEN
> IF(`mktgmsg_campaign_id` IS NULL, '', `mktgmsg_campaign_id`)
> ELSE ''
> END AS `message_campaign_instance_id` FROM source;
> -- return wrong value('')
> select CASE
> WHEN `mktgmsg_biz_type` = 'marketing_flow' THEN
> IFNULL(`marketing_flow_id`, '')
> WHEN `mktgmsg_biz_type` = 'mktgmsg_campaign' THEN
> IFNULL(`mktgmsg_campaign_id`, '')
> ELSE ''
> END AS `message_campaign_instance_id` FROM source;
> -- return correct value, the difference is [else return ' ']
> select CASE
> WHEN `mktgmsg_biz_type` = 'marketing_flow' THEN
> IFNULL(`marketing_flow_id`, '')
> WHEN `mktgmsg_biz_type` = 'mktgmsg_campaign' THEN
> IFNULL(`mktgmsg_campaign_id`, '')
> ELSE ' '
> END AS `message_campaign_instance_id` FROM source;
> {code}
>
>
>
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