作为标题,我具有以下代码:
SELECT
*
FROM
de.Department
WHERE
de.flag = 1
AND de.DepartmentNum IN (10,4)
AND de.status IN (0,-1,100)
AND datediff('dd',de.datequit,'30-SEP-19') > 9
datediff函数使我的查询运行非常慢(11条记录需要16秒),并且成本也很高(〜43k)。
这是我的datediff功能代码
create or replace FUNCTION DATEDIFF
(
P_TYPE_DATE IN VARCHAR2
, P_START_DATE IN TIMESTAMP
, P_END_DATE IN TIMESTAMP
) RETURN NUMBER AS
v_Result NUMBER := -1;
BEGIN
IF P_TYPE_DATE IS NOT NULL AND P_START_DATE IS NOT NULL AND P_END_DATE IS NOT NULL THEN
CASE UPPER(P_TYPE_DATE)
WHEN 'DD' THEN RETURN ROUND(TRUNC(P_END_DATE,'DD') - TRUNC(P_START_DATE,'DD'),0);
WHEN 'HH' THEN RETURN ROUND((TRUNC(P_END_DATE,'HH') - TRUNC(P_START_DATE,'HH')) * 24,0);
WHEN 'MI' THEN RETURN ROUND((TRUNC(P_END_DATE,'MI') - TRUNC(P_START_DATE,'MI')) * 24 * 60,0);
WHEN 'SS' THEN RETURN ROUND((TRUNC(P_END_DATE,'MI') - TRUNC(P_START_DATE,'MI')) * 24 * 60 * 60 + extract(second from (P_END_DATE - P_START_DATE)),0);
ELSE RETURN NULL;
END CASE;
END IF;
RETURN NULL;
EXCEPTION
WHEN OTHERS THEN
raise_application_error(-20001,'An error was encountered - '||SQLCODE||' -ERROR- '||SQLERRM);
END DATEDIFF;
我使用SELECT *,因为我想获得Department表中的几乎一列,因此,如果我选择一些需要的列,它就不会有任何变化。
我可以重写以提高性能和成本吗?
谢谢,谢谢!
我在SQL中创建了一个名为datediff的函数作为datediff函数,先生
不要使用自定义函数,因为它们会阻止Oracle在列上使用索引;而是将列与静态值进行比较:
SELECT *
FROM Department
WHERE flag = 1
AND DepartmentNum IN (10,4)
AND status IN (0,-1,100)
AND datequit > DATE '2019-09-30' + INTERVAL '9' DAY
或
AND datequit > DATE '2019-09-30' + NUMTODSINTERVAL( 9, 'DAY' )
或
AND datequit > DATE '2019-09-30' + 9