用戶定義函數在PostgreSQL中返回表

Question

我正在嘗試創建一個UDF，該UDF返回包含四個值的表：

CREATE TABLE ts_table
(
  id character varying, 
  year integer, 
  rank double precision, 
  votes integer
);

然后，使用UDF，我必須返回一個由定義的表（類似）：

CREATE FUNCTION ts_myfunc(text) RETURNS SETOF ts_table AS $$
    'SELECT id,year,rank,votes FROM productions NATURAL JOIN directors NATURAL JOIN ratings WHERE attr is NULL AND pid=$1 ORDER BY year;'
$$ LANGUAGE SQL;

但是，當我嘗試使用該命令創建UDF時，

ERROR:  syntax error at or near "'SELECT id,year,rank,votes FROM productions NATURAL JOIN directors NATURAL JOIN ratings WHERE attr is NULL AND pid=$1 ORDER BY year;'"
LINE 2: 'SELECT id,year,rank,votes FROM productions NATURAL JOIN dir...

Answer 1

更改以下行： 'SELECT id,year,rank,votes FROM productions NATURAL JOIN directors NATURAL JOIN ratings WHERE attr is NULL AND pid=$1 ORDER BY year;'

至

SELECT id,year,rank,votes FROM productions NATURAL JOIN directors NATURAL JOIN ratings WHERE attr is NULL AND pid=$1 ORDER BY year;

（刪除單引號）將解決此問題。