Postgresql: 动态SQL语句中不能使用Select into？

我的数据库版本是 PostgreSQL 8.4.7 。 下面是出错的存储过程：

CREATE or Replace FUNCTION func_getnextid( tablename varchar(240), idname varchar(20) default 'id') RETURNS integer AS $funcbody$ Declare sqlstring varchar(240); currentId integer; Begin sqlstring:= 'select max("' || idname || '") into currentId from "' || tablename || '";'; EXECUTE sqlstring; if currentId is NULL or currentId = 0 then return 1; else return currentId + 1; end if; End; $funcbody$ LANGUAGE plpgsq

执行后出现这样的错误：

SQL error:

ERROR:  EXECUTE of SELECT ... INTO is not implemented

CONTEXT:  PL/pgSQL function "func_getnextbigid" line 6 at EXECUTE statement

改成这样的就对了：

CREATE or Replace FUNCTION func_getnextid( tablename varchar(240), idname varchar(20) default 'id') RETURNS integer AS $funcbody$ Declare sqlstring varchar(240); currentId integer; Begin sqlstring:= 'select max("' || idname || '") from "' || tablename || '";'; EXECUTE sqlstring into currentId; if currentId is NULL or currentId = 0 then return 1; else return currentId + 1; end if; End; $funcbody$ LANGUAGE plpgsql;