相关疑难解决方法(0)

我写了一个函数,输出一个SELECT以文本形式组成的PostgreSQL 查询.现在我不想再输出文本,但实际上SELECT对数据库运行生成的语句并返回结果 - 就像查询本身一样.

到目前为止我所拥有的:

CREATE OR REPLACE FUNCTION data_of(integer)
  RETURNS text AS
$BODY$
DECLARE
   sensors varchar(100);   -- holds list of column names
   type    varchar(100);   -- holds name of table
   result  text;           -- holds SQL query
       -- declare more variables

BEGIN
      -- do some crazy stuff

      result := 'SELECT\r\nDatahora,' || sensors ||
      '\r\n\r\nFROM\r\n' || type ||
      '\r\n\r\nWHERE\r\id=' || $1 ||'\r\n\r\nORDER BY Datahora;';

      RETURN result;
END;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;
ALTER FUNCTION data_of(integer) OWNER TO postgres;

sensors …

我有一种情况,我想在两个视图之间返回连接.那是很多专栏.在sql server中很容易.但是在PostgreSQL中我加入时.我收到错误"需要列定义列表".

有什么方法可以绕过这个,我不想提供返回列的定义.

CREATE OR REPLACE FUNCTION functionA(username character varying DEFAULT ''::character varying, databaseobject character varying DEFAULT ''::character varying)
  RETURNS SETOF ???? AS
$BODY$
Declare 
SqlString varchar(4000) = '';
BEGIN
IF(UserName = '*') THEN
   Begin
   SqlString  := 'select * from view1 left join ' + databaseobject  + ' as view2 on view1.id = view2.id';
   End;
ELSE
    Begin
    SqlString := 'select * from view3 left join ' + databaseobject  + ' as view2 on view3.id = view2.id';
    End;
END IF; 
execute …