Mysql.Data

Iv'e been studying a pretty decent source bit by bit and got some understanding of it so far however I saw this error(rarely happens) when creating a new character and attempting to login.
What EXACTLY is the Mysql.Data telling me?

Code:

MySql.Data.MySqlClient.MySqlException (0x80004005): Duplicate entry '' for key 'PRIMARY'
   at MySql.Data.MySqlClient.MySqlStream.ReadPacket()
   at MySql.Data.MySqlClient.NativeDriver.GetResult(Int32& affectedRow, Int32& insertedId)
   at MySql.Data.MySqlClient.Driver.GetResult(Int32 statementId, Int32& affectedRows, Int32& insertedId)
   at MySql.Data.MySqlClient.Driver.NextResult(Int32 statementId, Boolean force)
   at MySql.Data.MySqlClient.MySqlDataReader.NextResult()
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader()
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteScalar()

If further explanation is needed please ask.