Eval Calculation-string: “2 * 3 + 4 * 5” in Postgresql

问题

I would like to evaluate a pure-calculation string in Postgres.

For example: eval('234 + 65 * 3')

The function is NOT constant, so could also simply be 2 + 2

Expecting something like SELECT eval('2 + 2') AS result

I read about huge security issues regarding eval() functions, but those seem to incorporate SELECT statements. Here pure calculation requirements.

回答1:

You need PL/pgSQL:

create or replace function f(_s text)
returns numeric as $$
declare i numeric;
begin
    execute format('select %s', _s) into i;
    return i;
end;
$$ language plpgsql;

select f('1 + 1');
 f 
---
 2

来源：https://stackoverflow.com/questions/43118512/eval-calculation-string-2-3-4-5-in-postgresql