Why is setting SQL variable is creating an error?

Question

Following SQL statement is creating an error with message : "Message: Fatal error encountered during command execution." "Inner exception: Parameter '@LastUserID' must be defined."

If I directly use LAST_INSERT_ID() instead of LastUserID, it always returns zero (hence fails at second insert) when executed like this.

I don't see my syntax is different than in mySQL document.

Could some one help me ?

string Query = @"INSERT INTO login (" +
                                    "LOGIN_EMAIL," +
                                    "LOGIN_PASSWORD," +
                                    "LOGIN_SALT," +
                                    "LOGIN_LAST_LOGIN_DATE," +
                                    //         "LOGIN_LAST_LOGIN_LOCATION," +
                                    "LOGIN_ACCOUNT_STATUS," +
                                    "LOGIN_LOGIN_ATTEMPTS," +
                                    "LOGIN_CREATED_DATE) " +
                                "VALUES (" +
                                    "@Parameter2," +
                                    "@Parameter3," +
                                    "@Parameter4," +
                                    "@Parameter5," +
                                    //                                        "@Parameter6," +
                                    "@Parameter6," +
                                    "@Parameter7," +
                                    "@Parameter8); " +
                                "SET @LastUserID = LAST_INSERT_ID(); " + 
                                "INSERT INTO user_role (" +
                                    "USER_ROLE_USER_ID," +
                                    "USER_ROLE_ROLE," +
                                    "USER_ROLE_STATUS," +
                                    "USER_ROLE_CREATED_DATE) " +
                                "SELECT " +
                                    "@LastUserID," +
                                    "@Parameter9," +
                                    "@Parameter10," +
                                    "@Parameter11 " +
                                "FROM dual WHERE NOT EXISTS (SELECT USER_ROLE_USER_ID FROM user_role " +
                                "WHERE USER_ROLE_USER_ID = @LastUserID AND USER_ROLE_ROLE = @Parameter9)";

                    MySqlCommand oCommand = new MySqlCommand(Query, oMySQLConnecion);

                oCommand.Transaction = tr;

Answer 1

Simple fix : Replace "$LastUserID" with "$'LastUserID'". The ephostophy makes the difference.