ORA-01406:    
        fetched column value was truncated
Cause:    
        In a host language program, a FETCH operation was forced to truncate a character string. The program buffer area for this column was not large enough to contain the entire string. The cursor return code from the fetch was +3.
Action:    
        Increase the column buffer area to hold the largest column value or perform other appropriate processing.

自己遇到了好多次这个问题，我遇到的问题一般是：

如：
        TAB1(col1 VARCHAR2(20));
                
        表中col1字段本来长度是20的，但我在OCI中取该字段数据用的长度小于20就出现ORA-01406问题了.