Store the key/data pair in the database, only if the key does not
            already appear in the database.
            
    Namespace: 
   BerkeleyDBAssembly: libdb_dotnet53 (in libdb_dotnet53.dll) Version: 5.3.21.0
Syntax
| C# | 
|---|
public void PutNoOverwrite( DatabaseEntry key, DatabaseEntry data, Transaction txn )  | 
| Visual Basic (Declaration) | 
|---|
Public Sub PutNoOverwrite ( _ key As DatabaseEntry, _ data As DatabaseEntry, _ txn As Transaction _ )  | 
| Visual C++ | 
|---|
public: void PutNoOverwrite( DatabaseEntry^ key, DatabaseEntry^ data, Transaction^ txn )  | 
Parameters
- key
 - Type: BerkeleyDB..::.DatabaseEntry
The key to store in the database 
- data
 - Type: BerkeleyDB..::.DatabaseEntry
The data item to store in the database 
- txn
 - Type: BerkeleyDB..::.Transaction
If the operation is part of an application-specified transaction, txn is a Transaction object returned from BeginTransaction()()(); if the operation is part of a Berkeley DB Concurrent Data Store group, txn is a handle returned from BeginCDSGroup()()(); otherwise null. 
Remarks
            This enforcement of uniqueness of keys applies only to the primary
            key, the behavior of insertions into secondary databases is not
            affected. In particular, the insertion of a record that would result
            in the creation of a duplicate key in a secondary database that
            allows duplicates would not be prevented by the use of this flag.