delphi – 插入UTF8数据库时格式错误的字符串

数据库字符集是UTF8.在db-connection UTF8中.

数据库：

var 
  Database: TIBDatabase;
begin
  ...
  Database.params.Clear;
  Database.params.Add('user ''SYSDBA'' password ''masterkey'' ');
  Database.params.Add('page_size 16384');
  Database.params.Add('default character set UTF8');

表：

CREATE TABLE NEW_TABLE (
    NEW_FIELD  VARCHAR(255)
);

连接代码：

Database.params.Clear;
  Database.params.Add('user_name=SYSDBA');
  Database.params.Add('password=masterke');
  Database.params.Add('sql_role_name=UTF8');
  Database.Open;

插入代码：

var
  IBSQL: TIBSQL;
begin
  IBSQL := TIBSQL.Create(nil);
  try
    IBSQL.Database := db;
    IBSQL.Transaction := tr

    IBSQL.SQL.Text := 'insert into NEW_TABLE (NEW_FIELD) values (:param)';

    IBSQL.params[0].Value := '?abc?'; // unsupported symbols :(

    if not IBSQL.Transaction.Active then
      IBSQL.Transaction.StartTransaction;

    IBSQL.ExecQuery; // "Malformed string" exception here

    if IBSQL.Transaction.Active then
      IBSQL.Transaction.Commit;
  finally
    FreeAndNil(IBSQL);
  end;
end;

我收到“格式错误的字符串”异常.如何插入此字符串？