postgresql - 无法在 postgreSQL 中触发异常 NO_DATA_FOUND

Question

即使返回的行或结果集为零，我也无法从 PostgreSql 8.2 中的函数触发异常 NO_DATA_FOUND。

这是我的代码；

 CREATE OR REPLACE FUNCTION func_ex() RETURNS trigger AS  

$func_ex$
    DECLARE               
        var_name  name;                 
    BEGIN
           Select empname INTO var_name from emp_table1 WHERE empid = 161232;  

    EXCEPTION
        WHEN NO_DATA_FOUND THEN 
        RAISE EXCEPTION 'No data found';
        RETURN NEW;
    END;
  return new
$func_ex$ LANGUAGE plpgsql;
-- End of Function

-- Creation of Trigger
CREATE TRIGGER insert_trigger1 AFTER update of empname
    ON emp_table1 EXECUTE PROCEDURE func_ex();


-- insertion enteries.
INSERT INTO emp_table1 (empid, empname, salary) values (124, ' Sapmle_CustormerName', '3000');

Answer 1

要触发 NO_DATA_FOUND 异常使用:

Select empname INTO STRICT var_name from emp_table1 WHERE empid = 161232;

详情在这里:http://www.postgresql.org/docs/current/static/plpgsql-statements.html

If STRICT is not specified in the INTO clause, then target will be setto the first row returned by the query, or to nulls if the queryreturned no rows.

If the STRICT option is specified, the query must return exactly onerow or a run-time error will be reported, either NO_DATA_FOUND (norows) or TOO_MANY_ROWS (more than one row).