谁来解释一下select * from XXXXX sample(50) t where rownum <= 5 rownum伪列,代表行号rownum<=5 选择前5行 解决方案 » 免费领取超大流量手机卡,每月29元包185G流量+100分钟通话, 中国电信官方发货 怯怯的问一句,sample(50)是什么意思? 学习,谁解释一下sample(50)是什么意思? 我库中一例: NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:04 74530 2004-08-12 18:30:04 74531 2004-08-12 18:30:04 74533 2004-08-12 18:30:04 74538 2004-08-12 18:30:04 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:05 74530 2004-08-12 18:30:05 74531 2004-08-12 18:30:05 74533 2004-08-12 18:30:05 74538 2004-08-12 18:30:05 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:05 74530 2004-08-12 18:30:05 74531 2004-08-12 18:30:05 74533 2004-08-12 18:30:05 74538 2004-08-12 18:30:05 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:05 74530 2004-08-12 18:30:05 74531 2004-08-12 18:30:05 74533 2004-08-12 18:30:05 74538 2004-08-12 18:30:05 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:06 74530 2004-08-12 18:30:06 74531 2004-08-12 18:30:06 74533 2004-08-12 18:30:06 74538 2004-08-12 18:30:06 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:06 74530 2004-08-12 18:30:06 74531 2004-08-12 18:30:06 74533 2004-08-12 18:30:06 74538 2004-08-12 18:30:06 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:06 74530 2004-08-12 18:30:06 74531 2004-08-12 18:30:06 74533 2004-08-12 18:30:06 74538 2004-08-12 18:30:06 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:07 74530 2004-08-12 18:30:07 74531 2004-08-12 18:30:07 74533 2004-08-12 18:30:07 74538 2004-08-12 18:30:07 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:07 74530 2004-08-12 18:30:07 74531 2004-08-12 18:30:07 74533 2004-08-12 18:30:07 74538 2004-08-12 18:30:07 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74514 2004-08-12 18:30:07 74529 2004-08-12 18:30:07 74532 2004-08-12 18:30:07 74534 2004-08-12 18:30:07 74537 2004-08-12 18:30:07 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74514 2004-08-12 18:30:08 74529 2004-08-12 18:30:08 74532 2004-08-12 18:30:08 74534 2004-08-12 18:30:08 74537 2004-08-12 18:30:08 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74514 2004-08-12 18:30:08 74529 2004-08-12 18:30:08 74532 2004-08-12 18:30:08 74534 2004-08-12 18:30:08 74537 2004-08-12 18:30:08 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74514 2004-08-12 18:30:08 74529 2004-08-12 18:30:08 74532 2004-08-12 18:30:08 74534 2004-08-12 18:30:08 74537 2004-08-12 18:30:08 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74514 2004-08-12 18:30:09 74529 2004-08-12 18:30:09 74532 2004-08-12 18:30:09 74534 2004-08-12 18:30:09 74537 2004-08-12 18:30:09 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74514 2004-08-12 18:30:09 74529 2004-08-12 18:30:09 74532 2004-08-12 18:30:09 74534 2004-08-12 18:30:09 74537 2004-08-12 18:30:09 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74514 2004-08-12 18:30:09 74529 2004-08-12 18:30:09 74532 2004-08-12 18:30:09 74534 2004-08-12 18:30:09 74537 2004-08-12 18:30:09 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74514 2004-08-12 18:30:09 74529 2004-08-12 18:30:09 74532 2004-08-12 18:30:09 74534 2004-08-12 18:30:09 74537 2004-08-12 18:30:09 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74514 2004-08-12 18:30:10 74529 2004-08-12 18:30:10 74532 2004-08-12 18:30:10 74534 2004-08-12 18:30:10 74537 2004-08-12 18:30:10 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74514 2004-08-12 18:30:10 74529 2004-08-12 18:30:10 74532 2004-08-12 18:30:10 74534 2004-08-12 18:30:10 74537 2004-08-12 18:30:10 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:10 74535 2004-08-12 18:30:10 74537 2004-08-12 18:30:10 74538 2004-08-12 18:30:10 74539 2004-08-12 18:30:10 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:11 74535 2004-08-12 18:30:11 74537 2004-08-12 18:30:11 74538 2004-08-12 18:30:11 74539 2004-08-12 18:30:11 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:11 74535 2004-08-12 18:30:11 74537 2004-08-12 18:30:11 74538 2004-08-12 18:30:11 74539 2004-08-12 18:30:11 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:11 74535 2004-08-12 18:30:11 74537 2004-08-12 18:30:11 74538 2004-08-12 18:30:11 74539 2004-08-12 18:30:11 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:12 74535 2004-08-12 18:30:12 74537 2004-08-12 18:30:12 74538 2004-08-12 18:30:12 74539 2004-08-12 18:30:12 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:12 74535 2004-08-12 18:30:12 74537 2004-08-12 18:30:12 74538 2004-08-12 18:30:12 74539 2004-08-12 18:30:12 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:12 74535 2004-08-12 18:30:12 74537 2004-08-12 18:30:12 74538 2004-08-12 18:30:12 74539 2004-08-12 18:30:12 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:13 74535 2004-08-12 18:30:13 74537 2004-08-12 18:30:13 74538 2004-08-12 18:30:13 74539 2004-08-12 18:30:13 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74529 2004-08-12 18:30:13 74535 2004-08-12 18:30:13 74537 2004-08-12 18:30:13 74538 2004-08-12 18:30:13 74539 2004-08-12 18:30:13 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2----------- ------------------------------ 74514 2004-08-12 18:30:13 74531 2004-08-12 18:30:13 74532 2004-08-12 18:30:13 74533 2004-08-12 18:30:13 74534 2004-08-12 18:30:13执行语句都是:select NBBH,To_Char(sysdate,'yyyy-mm-dd hh24:mi:ss') from m_exes sample(50) t where rownum <= 5; oracle监听器的问题,在线等 各位大侠,帮帮忙 SPOOL 最大文件限制 请问oracle如何查询奇数行数据 问一个translate的问题 oracle查询问题 初学者,请教一个简单问题 proc在linux下编译的问题 关于如何监控imp 关于oracle8.17的备份问题。 PL/SQL表 用 select max() 语句,记录为空的时候怎样做处理呢?
NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:04
74530 2004-08-12 18:30:04
74531 2004-08-12 18:30:04
74533 2004-08-12 18:30:04
74538 2004-08-12 18:30:04 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:05
74530 2004-08-12 18:30:05
74531 2004-08-12 18:30:05
74533 2004-08-12 18:30:05
74538 2004-08-12 18:30:05 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:05
74530 2004-08-12 18:30:05
74531 2004-08-12 18:30:05
74533 2004-08-12 18:30:05
74538 2004-08-12 18:30:05 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:05
74530 2004-08-12 18:30:05
74531 2004-08-12 18:30:05
74533 2004-08-12 18:30:05
74538 2004-08-12 18:30:05 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:06
74530 2004-08-12 18:30:06
74531 2004-08-12 18:30:06
74533 2004-08-12 18:30:06
74538 2004-08-12 18:30:06 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:06
74530 2004-08-12 18:30:06
74531 2004-08-12 18:30:06
74533 2004-08-12 18:30:06
74538 2004-08-12 18:30:06 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:06
74530 2004-08-12 18:30:06
74531 2004-08-12 18:30:06
74533 2004-08-12 18:30:06
74538 2004-08-12 18:30:06 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:07
74530 2004-08-12 18:30:07
74531 2004-08-12 18:30:07
74533 2004-08-12 18:30:07
74538 2004-08-12 18:30:07 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:07
74530 2004-08-12 18:30:07
74531 2004-08-12 18:30:07
74533 2004-08-12 18:30:07
74538 2004-08-12 18:30:07 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74514 2004-08-12 18:30:07
74529 2004-08-12 18:30:07
74532 2004-08-12 18:30:07
74534 2004-08-12 18:30:07
74537 2004-08-12 18:30:07 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74514 2004-08-12 18:30:08
74529 2004-08-12 18:30:08
74532 2004-08-12 18:30:08
74534 2004-08-12 18:30:08
74537 2004-08-12 18:30:08 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74514 2004-08-12 18:30:08
74529 2004-08-12 18:30:08
74532 2004-08-12 18:30:08
74534 2004-08-12 18:30:08
74537 2004-08-12 18:30:08 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74514 2004-08-12 18:30:08
74529 2004-08-12 18:30:08
74532 2004-08-12 18:30:08
74534 2004-08-12 18:30:08
74537 2004-08-12 18:30:08 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74514 2004-08-12 18:30:09
74529 2004-08-12 18:30:09
74532 2004-08-12 18:30:09
74534 2004-08-12 18:30:09
74537 2004-08-12 18:30:09 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74514 2004-08-12 18:30:09
74529 2004-08-12 18:30:09
74532 2004-08-12 18:30:09
74534 2004-08-12 18:30:09
74537 2004-08-12 18:30:09 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74514 2004-08-12 18:30:09
74529 2004-08-12 18:30:09
74532 2004-08-12 18:30:09
74534 2004-08-12 18:30:09
74537 2004-08-12 18:30:09 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74514 2004-08-12 18:30:09
74529 2004-08-12 18:30:09
74532 2004-08-12 18:30:09
74534 2004-08-12 18:30:09
74537 2004-08-12 18:30:09 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74514 2004-08-12 18:30:10
74529 2004-08-12 18:30:10
74532 2004-08-12 18:30:10
74534 2004-08-12 18:30:10
74537 2004-08-12 18:30:10 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74514 2004-08-12 18:30:10
74529 2004-08-12 18:30:10
74532 2004-08-12 18:30:10
74534 2004-08-12 18:30:10
74537 2004-08-12 18:30:10 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:10
74535 2004-08-12 18:30:10
74537 2004-08-12 18:30:10
74538 2004-08-12 18:30:10
74539 2004-08-12 18:30:10 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:11
74535 2004-08-12 18:30:11
74537 2004-08-12 18:30:11
74538 2004-08-12 18:30:11
74539 2004-08-12 18:30:11 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:11
74535 2004-08-12 18:30:11
74537 2004-08-12 18:30:11
74538 2004-08-12 18:30:11
74539 2004-08-12 18:30:11 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:11
74535 2004-08-12 18:30:11
74537 2004-08-12 18:30:11
74538 2004-08-12 18:30:11
74539 2004-08-12 18:30:11 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:12
74535 2004-08-12 18:30:12
74537 2004-08-12 18:30:12
74538 2004-08-12 18:30:12
74539 2004-08-12 18:30:12 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:12
74535 2004-08-12 18:30:12
74537 2004-08-12 18:30:12
74538 2004-08-12 18:30:12
74539 2004-08-12 18:30:12 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:12
74535 2004-08-12 18:30:12
74537 2004-08-12 18:30:12
74538 2004-08-12 18:30:12
74539 2004-08-12 18:30:12 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:13
74535 2004-08-12 18:30:13
74537 2004-08-12 18:30:13
74538 2004-08-12 18:30:13
74539 2004-08-12 18:30:13 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74529 2004-08-12 18:30:13
74535 2004-08-12 18:30:13
74537 2004-08-12 18:30:13
74538 2004-08-12 18:30:13
74539 2004-08-12 18:30:13 NBBH TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
----------- ------------------------------
74514 2004-08-12 18:30:13
74531 2004-08-12 18:30:13
74532 2004-08-12 18:30:13
74533 2004-08-12 18:30:13
74534 2004-08-12 18:30:13
执行语句都是:select NBBH,To_Char(sysdate,'yyyy-mm-dd hh24:mi:ss') from m_exes sample(50) t where rownum <= 5;