原文:
發(fā)現(xiàn)SQL Server驚天大秘密!!
--
set?statistics?xml?on
CREATE ? TABLE ?T_TEST(ID? INT ? IDENTITY ? PRIMARY ? KEY ,CreateTime?DATE)
INSERT ? INTO ?T_TEST? SELECT ? ' 2011-11-04 '
UNION ? ALL ? SELECT ? ' 2011-11-04 '
UNION ? ALL ? SELECT ? ' 2011-11-04 '
UNION ? ALL ? SELECT ? ' 2011-11-05 '
UNION ? ALL ? SELECT ? ' 2011-11-05 '
UNION ? ALL ? SELECT ? ' 2011-11-05 '
SELECT ? * ? FROM ?T_TEST
SELECT ? COUNT ( * )? FROM ?T_TEST?
WHERE ?CreateTime >= ' 2011-11-04?00:00:00 ' ? AND ?CreateTime? <= ' 2011-11-04?23:59:59 '
-- 等價(jià)于(返回3行,這個(gè)沒有問題)
SELECT ? COUNT ( * )? FROM ?T_TEST?
WHERE ?CreateTime = ' 2011-11-04 '
SELECT ? COUNT ( * )? FROM ?T_TEST?
WHERE ?CreateTime >= ' 2011-11-04?00:00:00 ' ? AND ?CreateTime? < ' 2011-11-04?23:59:59 '
-- 等價(jià)于(返回0行,因?yàn)閣here條件無(wú)意義,這個(gè)也沒有問題)
SELECT ? COUNT ( * )? FROM ?T_TEST?
WHERE ?CreateTime >= ' 2011-11-04 ' ? AND ?CreateTime? < ' 2011-11-04 '
-- 傳入?yún)?shù)為datetime類型(它為什么能返回3行?!!!!這是為什么!!)
SP_executesql?N '
????select?COUNT(*)?
????from?T_TEST
????where?CreateTime>=@BeginTime?and?CreateTime<@EndTime
' ,N ' @BeginTime?datetime,@EndTime?datetime ' ,
@BeginTime = ' 2011-11-04?00:00:00 ' ,
@EndTime = ' 2011-11-04?23:59:59 ' ????
-- 修改了傳參類型為date類型(返回0行)
SP_executesql?N '
????select?COUNT(*)?
????from?T_TEST
????where?CreateTime>=@BeginTime?and?CreateTime<@EndTime
' ,N ' @BeginTime?date,@EndTime?date ' ,
@BeginTime = ' 2011-11-04?00:00:00 ' ,
@EndTime = ' 2011-11-04?23:59:59 ' ????
CREATE ? TABLE ?T_TEST(ID? INT ? IDENTITY ? PRIMARY ? KEY ,CreateTime?DATE)
INSERT ? INTO ?T_TEST? SELECT ? ' 2011-11-04 '
UNION ? ALL ? SELECT ? ' 2011-11-04 '
UNION ? ALL ? SELECT ? ' 2011-11-04 '
UNION ? ALL ? SELECT ? ' 2011-11-05 '
UNION ? ALL ? SELECT ? ' 2011-11-05 '
UNION ? ALL ? SELECT ? ' 2011-11-05 '
SELECT ? * ? FROM ?T_TEST
SELECT ? COUNT ( * )? FROM ?T_TEST?
WHERE ?CreateTime >= ' 2011-11-04?00:00:00 ' ? AND ?CreateTime? <= ' 2011-11-04?23:59:59 '
-- 等價(jià)于(返回3行,這個(gè)沒有問題)
SELECT ? COUNT ( * )? FROM ?T_TEST?
WHERE ?CreateTime = ' 2011-11-04 '
SELECT ? COUNT ( * )? FROM ?T_TEST?
WHERE ?CreateTime >= ' 2011-11-04?00:00:00 ' ? AND ?CreateTime? < ' 2011-11-04?23:59:59 '
-- 等價(jià)于(返回0行,因?yàn)閣here條件無(wú)意義,這個(gè)也沒有問題)
SELECT ? COUNT ( * )? FROM ?T_TEST?
WHERE ?CreateTime >= ' 2011-11-04 ' ? AND ?CreateTime? < ' 2011-11-04 '
-- 傳入?yún)?shù)為datetime類型(它為什么能返回3行?!!!!這是為什么!!)
SP_executesql?N '
????select?COUNT(*)?
????from?T_TEST
????where?CreateTime>=@BeginTime?and?CreateTime<@EndTime
' ,N ' @BeginTime?datetime,@EndTime?datetime ' ,
@BeginTime = ' 2011-11-04?00:00:00 ' ,
@EndTime = ' 2011-11-04?23:59:59 ' ????
-- 修改了傳參類型為date類型(返回0行)
SP_executesql?N '
????select?COUNT(*)?
????from?T_TEST
????where?CreateTime>=@BeginTime?and?CreateTime<@EndTime
' ,N ' @BeginTime?date,@EndTime?date ' ,
@BeginTime = ' 2011-11-04?00:00:00 ' ,
@EndTime = ' 2011-11-04?23:59:59 ' ????
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