函数中if语句的Postgresql语法错误

我试图在postgresql中编写函数，但得到了if语句的语法错误：

CREATE OR REPLACE FUNCTION getallcampuses(IN a character varying, IN b character varying)
  RETURNS TABLE(campusid charactervarying, campusname character varying) AS
$BODY$
BEGIN
if $1 = 'PREK' then
     SELECT * from "SIS_campus";
ELSE
    BEGIN
       IF $2 = 'DAll' then
           SELECT distinct(district_id) || 'ALL' AS CampusID, ' District' AS CampusName

           UNION

           SELECT campus_id, name
           FROM   "SIS_campus"
           WHERE  district_name IS NOT NULL
           order by name;
       Elsif $2 = 'All' then

           SELECT campus_id, name
           FROM   "SIS_campus"
           WHERE  district_name IS NOT NULL
           and isnumeric(name) = 0
           order by name;
        end if;
    END
end if;
END
$BODY$
LANGUAGE sql;

以下是错误：

ERROR:  syntax error at or near "if"
LINE 5: if $1 = 'PREK' then
        ^

---

函数体是PL/PgSQL，但是您声明了它

语言sql

如果您正在编写PL/PgSQL，请使用

语言plpgsql

---

（）

您在

Elsif$2='All'有一个输入错误，那么

感谢您提供完整的函数体和准确的错误消息文本。这是非常罕见的，值得赞赏。（不过，今后也请在文本中添加您的PostgreSQL版本）。