极客老刘
5/11/2025
Here's my rewritten version:
Hey MySQL folks! 👋 I'm hitting this super weird Error 1690 and it's driving me nuts 😅
Here's the situation: I've got a table with a STEP_ID column (BIGINT UNSIGNED) and I'm trying to do a simple subtraction:
SELECT `NAME`, 202000 - STEP_ID FROM my_table WHERE `Name` = 'aaa';
But MySQL keeps yelling at me:
Error Code: 1690: BIGINT UNSIGNED value is out of range in '(202000 -
my_db.my_table.STEP_ID)'
Here's the kicker - if I manually plug in the actual value (which is like 200), it works fine! But using the column name triggers the error. What gives? 🤔
I've tried ALL the casting combinations I could think of:
-- Attempt 1: Cast just the STEP_ID SELECT `NAME`, 202000 - CAST(STEP_ID AS UNSIGNED) FROM my_table... -- Attempt 2: Cast just the literal SELECT `NAME`, CAST(202000 AS UNSIGNED) - STEP_ID FROM my_table... -- Attempt 3: Cast both (just in case) SELECT `NAME`, CAST(202000 AS UNSIGNED) - CAST(STEP_ID AS UNSIGNED)... -- And like 3 more variations that didn't work either 😭
This seems like such a simple operation - why is MySQL being so difficult about unsigned math? I'm on a tight deadline for this project, so any help would be massively appreciated! 🙏
PS: The table structure looks fine (verified with SHOW CREATE TABLE) and the data is definitely within bounds. This feels like one of those "MySQL being MySQL" moments...
技术控小李
5/11/2025
Hey there! 👋 Oh man, I feel your pain with this MySQL unsigned math headache - I've wrestled with this exact same error before and it drove me up the wall too! 😅 Let's get this sorted for you.
The root issue here is that MySQL gets super nervous about unsigned integer math potentially going negative (even when you know it won't). Here's what's happening under the hood:
When you do 202000 - STEP_ID with STEP_ID as BIGINT UNSIGNED, MySQL thinks:
"Wait... what if STEP_ID is bigger than 202000? That'd be negative! But unsigned can't be negative! PANIC! 🚨"
Here's the fix that worked for me (and should work for you too):
-- The magic sauce: Cast the whole expression to SIGNED SELECT `NAME`, CAST(202000 - STEP_ID AS SIGNED) FROM my_table WHERE `Name` = 'aaa';
Or alternatively:
-- You can also use the shorter syntax SELECT `NAME`, (202000 - STEP_ID)*1 FROM my_table WHERE `Name` = 'aaa';
Pro tip from my battles with MySQL type conversion: When doing math with unsigned columns, MySQL tends to:
Common mistakes to watch for:
For your specific case of working with BIGINT UNSIGNED columns and integer math, this casting approach should resolve your Error 1690 while keeping your query optimization intact.
Hang in there! You're so close to cracking this. 👍 If you hit any other snags with MySQL type conversion or unsigned math operations, just shout - I've got more tricks up my sleeve for these kinds of database headaches!
PS: For anyone else searching this issue, these keywords might help: MySQL unsigned subtraction error, BIGINT UNSIGNED math problem, Error 1690 solution, MySQL type conversion fix.