When connecting Oracle in.NET and using dataAdapter fill, the exception of OCI-22053: overflow error occurs, because the data type precision of.NET is smaller than that of Oracle, such as
Select sysdate- ISSUetime as Timediff from sometable returns an excessive precision
Select TRUNc (sysdate-issuetime,2) as Timediff from sometable.
There are other ways to do this online:
http://excel.cnblogs.com/archive/2005/11/14/276202.html using the new ODP.NET da. SafeMapping. Add (field name 1, typeof (System. String)); Method converts all fields to String. But I went to the Oracle website and found that the 9207 version of ODAC is 80M… I’m too lazy to download.

 
The Oracle numeric data type can store up to 38 bytes of precision.
the Oracle value
may become too large when converting the Oracle value to the common language runtime data type. This causes an Oracle OCI-22053 overflow error.
The solution is to use the round function.
How to use the Oracle Round function (rounded)
Description: Returns a value that is rounded to the specified number of decimal digits.
SELECT ROUND( number, [ decimal_places ] ) FROM DUAL
Parameters:
Number: The number you want to process
Decimal_places: Round up and take a few decimal places (default is 0)
Sample :
Select round (123.456) from dual; The back 123
Select round(123.456, 0) from Dual; The back 123
Select round(123.456, 1) from Dual; The back 123.5
Select round(123.456, 2) from Dual; The back 123.46
Select round(123.456, 3) from Dual; The back 123.456
Select round(-123.456, 2) from dual; The back to 123.46
 
From:
http://blog.csdn.net/xeonol/article/details/726133