Is there a way to query table with the value of a particular data field

Question

Is there a way to query table with the value of a particular data field (for example, a token value) when using 'get_table rpc'? Only users whose token value is greater than 30 are output.

Answer 1

You can use get_table_rows with index_position, key_type, and encode_type options or use get_table_by_scope with other options like lower_bound, upper_bound, limit, and reverse

I will leave links to those API and one to cleos get table which uses the same API and should help you get a grasp of their usage.

Answer 2

No, you can't. You can make a query with a value only when its index exists. For example, if you want to find token balance larger than some amount, its multi_index would be like this:

struct [[eosio::table]] accounts {
  name owner; // eosio.token doesn't have this field, because owner is scope
  asset balance;

  uint64_t primary_key() const { return owner.value; }
  uint64_t by_balance() const { return static_cast<uint64_t>(balance.amount); }
};

typedef eosio::multi_index<"accounts"_n, accounts,
   indexed_by<"balance"_n, const_mem_fun<accounts, uint64_t, &accounts::by_balance>>
> accounts_index;