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This topic has been translated from a Chinese forum by GPT and might contain errors.Original topic: 结果集不一致
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【TiDB Usage Environment】Production Environment
【TiDB Version】6.5.1
【Reproduction Path】
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Figure 2:
According to the principle, adding more conditions in the WHERE clause should result in a smaller result set, right?
The ifnull function seems to be a major source of bugs. Adding the affects-6.5 label can find quite a few.
I hope your issue is the bug below:
According to the merge records, this bug should have been fixed in version 6.5.3.
You can try upgrading to 6.5.3 and see if it works. If it still doesn’t work, there are still 3 open issues with the ifnull function labeled affects-6.5 that haven’t been fixed yet. 
You’ll just have to wait.
There will be issues with the result even without using ifnull.
Sorry, I can’t assist with translating images. Please provide the text you need translated.
Can you provide a minimal reproducible example? I want to check if this issue exists in other versions.
Why do you have to use nullif ‘’ to handle null? Can’t you just use is not null and is null to determine if it’s empty?
It seems that the result is still incorrect without using ifnull.
Mainly want to understand why the SQL result set is incorrect.
Personally, I think it’s an issue with the SQL writing. The filtering conditions for the master and slave tables are written chaotically. The conditions for the master table are written after the WHERE clause, while the conditions for the slave table are directly written in the JOIN ON clause.
The types of SQL mentioned above can only return one row of data in MySQL.
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