message: convert to string
diff: @@ -256,26 +256,8 @@ static int swoole_mysql_coro_execute(zval *zobject, mysql_client *client, zval *
  {
  zval *value;
  SW_HASHTABLE_FOREACH_START(Z_ARRVAL_P(params), value)
  - if (Z_TYPE_P(value) == IS_LONG)
  - {
  - mysql_int2store(p, SW_MYSQL_TYPE_LONG);
  - p += 2;
  - }
  - else if (Z_TYPE_P(value) == IS_STRING)
  - {
  mysql_int2store(p, SW_MYSQL_TYPE_VAR_STRING);
  p += 2;
  - }
  - else if (Z_TYPE_P(value) == IS_DOUBLE)
  - {
  - mysql_int2store(p, SW_MYSQL_TYPE_DOUBLE);
  - p += 2;
  - }
  - else
  - {
  - swoole_php_fatal_error(E_WARNING, "unknown data type.");
  - return SW_ERR;
  - }
  SW_HASHTABLE_FOREACH_END();
  }
  @@ -287,17 +269,7 @@ static int swoole_mysql_coro_execute(zval *zobject, mysql_client *client, zval *
  {
  zval *value;
  SW_HASHTABLE_FOREACH_START(Z_ARRVAL_P(params), value)
  - if (Z_TYPE_P(value) == IS_LONG)
  - {
  - lval = 0;
  - mysql_int8store(&lval, Z_LVAL_P(value));
  - if (swString_append_ptr(mysql_request_buffer, (char*) &lval, sizeof(lval)) < 0)
  - {
  - return SW_ERR;
  - }
  - }
  - else if (Z_TYPE_P(value) == IS_STRING)
  - {
  + convert_to_string(value);
  lval = mysql_write_lcb(buf, Z_STRLEN_P(value));
  if (swString_append_ptr(mysql_request_buffer, buf, lval) < 0)
  {
  @@ -307,12 +279,6 @@ static int swoole_mysql_coro_execute(zval *zobject, mysql_client *client, zval *
  {
  return SW_ERR;
  }
  - }
  - else
  - {
  - swoole_php_fatal_error(E_WARNING, "unknown data type.");
  - return SW_ERR;
  - }
  SW_HASHTABLE_FOREACH_END();
  }
  