MySQL Configuration to auto truncate decimal value - mysql

Question

I've a table with a field DECIMAL(9,2) and I've 2 servers running both mysql 5.7
If I run this code
INSERT INTO `money_accounts` (`balance`) VALUES (9999999999.99);
On one of the servers it got inserted and value is truncated, on the other it raise a Out of range value for column balance error.
My question is, what is the configuration value that makes this happen? or why it's happening in one server and not in the other?

Answer 1

The definition
DECIMAL(9,2)
means 9 digits of total precision, with 2 digits after the decimal place. The value
9999999999.99
has 12 total digits of precision, with 2 after the decimal place. Hence, the value is out of range. Rightfully, MySQL should have thrown an out of range error in both cases. In the case where it "worked," my guess is that truncation occurred.
By the way, you should be using DECIMAL(12,2) or wider to store the value in your question.
Update:
One possible explanation for why one of your servers was doing the insertion while the other failed is that the first has traditional mode turned off. Run the following on both servers:
SELECT ##SESSION.sql_mode
If you see output looking like
STRICT_TRANS_TABLES, STRICT_ALL_TABLES, ...
then the server is running in traditional mode, which means it won't truncate but will reject. To turn it off, try running
SET SESSION sql_mode=''
and them the insert should succeed (with truncation). But in any case, you should not be relying on truncation in production. If you need more precision, then widen the column.
Reference: Automatically trimming length of string submitted to MySQL

Answer 2

If we read the documentation: http://dev.mysql.com/doc/refman/5.7/en/out-of-range-and-overflow.html
When MySQL stores a value in a numeric column that is outside the
permissible range of the column data type, the result depends on the
SQL mode in effect at the time
If strict SQL mode is enabled, MySQL rejects the out-of-range value
with an error, and the insert fails, in accordance with the SQL
standard.
If no restrictive modes are enabled, MySQL clips the value to the
appropriate endpoint of the range and stores the resulting value
instead.
So it means that You should set necessary sql mode that will not fail when out-of-range error happens.
There is no config parameter about that.
And resolution of same issue we can see here that says that disabling STRICT_TRANS_TABLES and STRICT_ALL_TABLES modes can fix Your problem.