Postgresql 错误没有函数匹配给定的名称和参数类型。您可能需要添加显式类型转换

Question

declare r double precision; b double precision; c double precision;
begin

  r:=9.2;
  b:=2.3;
  c:=r/b;

  select log(2.7, c);
  ...

但是我收到这段代码的错误:

ERROR: function log(numeric, double precision) does not exist LINE 1: select log(2.7, c)

HINT: No function matches the given name and argument types. You might need to add explicit type casts.

QUERY: select log(2.7, c) CONTEXT: PL/pgSQL function inline_code_block line 11 at SQL statement SQL state: 42883

Answer 1

As documented in the manual带有两个参数的 log() 函数需要 numeric 而不是 double precision

do
$$
declare
  r numeric; 
  b numeric; 
  c numeric;
  result numeric;
begin

  r:=9.2;
  b:=2.3;
  c:=r/b;

  result := log(2.7, c);
  raise notice 'Result %', result;
end;
$$