How to fix Error 1406 while using Connector/C++?

[Water Lin]

I am using MySQL Connector/C++ as client, but I meet Error code 1406
while I am trying to insert Blob kind of data into MySQL. The long data is stored as std::string my problem, and I convert it to std::istringstream then use setBlob() to insert this data.

The size of Blob I want to insert is 100K. The MySQL server gives me a
error message:
--------------
ERR: Data too long for column 'longstring' at row 1 (MySQL error code:
1406, SQLState: 22001 )
--------------

I am using setBlob() to insert this data. But this still happen. Why?

Thanks

Water Lin