极客小王
10/18/2025
Help! MySQL Error 1690 driving me nuts with unsigned BIGINT subtraction 😫
Hey fellow devs! I'm stuck with this super weird MySQL error and I'm about to lose my mind. Here's the deal:
I've got a table with a STEP_ID column defined as BIGINT UNSIGNED. When I try to subtract it from a fixed number, MySQL throws this error:
-- This fails with Error 1690: BIGINT UNSIGNED value is out of range SELECT `NAME`, 202000 - STEP_ID FROM my_table WHERE `Name` = 'aaa';
The crazy part? If I manually enter the actual value (which is 202000) instead of using the column name, it works fine! 🤯
Here's what I've tried so far (spoiler: nothing works):
-- Attempt 1: Casting STEP_ID SELECT `NAME`, 202000 - CAST(STEP_ID AS UNSIGNED) FROM my_table... -- Nope -- Attempt 2: Casting the literal SELECT `NAME`, CAST(202000 AS UNSIGNED) - STEP_ID FROM my_table... -- Still nope -- Attempt 3: Double casting SELECT `NAME`, CAST(202000 AS UNSIGNED) - CAST(STEP_ID AS UNSIGNED)... -- WTF still fails -- Attempt 4: Casting the whole expression SELECT `NAME`, CAST((202000 - STEP_ID) AS UNSIGNED)... -- MySQL still hates me
This makes zero sense because the actual math (202000 - 202000) should obviously be 0, which is definitely within BIGINT UNSIGNED range!
Any MySQL wizards out there who can explain why this is happening? I'm on a tight deadline and this is blocking my progress 😅
PS: I'm using MySQL 8.0 if that helps. Also, why does MySQL have to be so dramatic about unsigned integers? 🙄
#mysql #database #help #bigint #unsigned #weirdbugs
工程师老张
10/18/2025
Hey there! 👋 Oh man, I feel your pain with this one! I remember banging my head against this exact same error a while back - MySQL's unsigned integer handling can be so dramatic sometimes, right? 😅
Here's the deal with Error 1690: MySQL is being overly protective with unsigned math operations. When you subtract a BIGINT UNSIGNED from a smaller number, MySQL freaks out because the result could be negative (even if it isn't in your case). It's like that overprotective friend who won't let you cross the street even when there are no cars coming. 🚗💨
The solution? You need to tell MySQL it's okay to handle potential negatives by using SIGNED casting. Here's what works:
-- The magic fix! Cast at least one operand to SIGNED SELECT `NAME`, 202000 - CAST(STEP_ID AS SIGNED) FROM my_table WHERE `Name` = 'aaa';
Or alternatively:
-- This works too - cast the whole expression SELECT `NAME`, CAST(202000 - STEP_ID AS SIGNED) FROM my_table WHERE `Name` = 'aaa';
Pro tip from my own battle scars: ⚠️ When working with unsigned columns, I now make it a habit to:
Fun fact: This behavior happens because MySQL evaluates the data types before looking at the actual values. So even though 202000-202000=0 is safe, MySQL sees "unsigned - unsigned" and panics first, asks questions never. 🙈
Hang in there! You're not crazy - this is just one of MySQL's quirky behaviors we all stumble over. Let me know if you hit any other snags with this - happy to help debug! 🛠️
#MySQLProblems #UnsignedMathStruggles #DatabaseWoes #DevLife