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1.当表的字段类型是varchar2时,无论是varchar2(4000 char)还是varchar2(4000 byte),最大长都是4000字节。 2.当在plsql中的变量是varchar2时,最大长是32767字节。 3.当func的参数类型是varchar2时,最大长是32767字节。 4.当func的返回值类型是varchar2时,最大长是4000字节。
mongoimport -d stock_modeling -c t_tick --type csv --file SH#600000.csv --fields stock_code,tick_time,open,high,low,close,volume,turn_volume,restoration_right,exchange
Interface ChannelPipeline public interface ChannelPipeline extends Iterable<Map.Entry<String,ChannelHandler>> A list of ChannelHandlers which handles or intercepts inbound events and outbound operations of a Channel. ChannelPipeline implements an advanced form of the Intercepting Filter ...
jdk : https://www.digitalocean.com/community/tutorials/how-to-install-java-on-ubuntu-with-apt-get mysql: https://help.ubuntu.com/12.04/serverguide/mysql.html mongodb: http://askubuntu.com/questions/147135/how-can-i-uninstall-mongodb-and-reinstall-the-latest-version
SELECT t2.team, MIN(t2.y) start_hm, MAX(t2.y) end_hm FROM ( SELECT team,y,y - rank y1 from ( SELECT tmp.team, tmp.y, IF(@groupid = tmp.team,@rank := @rank + 1,@rank := 1) AS rank, @groupid := tmp.te ...
最近看到一个问题(原帖地址:http://topic.csdn.net/u/20120604/09/b56a0996-3c5a-4c35-9423-8b68d1284db6.html) -- 表TB1 START_ID END_ID ---------- ---------- 1 3 4 6 7 9 10 12 13 15 16 18 19 ...

Clean Code

    博客分类:
  • Java
//bad private void printGuessStatistics(char candidate, int count) { String number; String verb; String pluralModifier; if (count == 0) { number = "no"; verb = "are"; pluralModifier = "s"; } else if (count == 1) { ...
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <head> <title>Untitled </title> <script> window.onload = function() { var childs = document.getElementById("container") ...
db_file_multiblock_read_count = 32 実行計画 ---------------------------------------------------------- 0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=35 Card=1 Bytes=13) 1 0 SORT (AGGREGATE) 2 1 TABLE ACCESS (FULL) OF 'T1' (TABLE) (Cost=35 Card=9872 Bytes=128336) db_fil ...

Oracle的行列转换

行转列: 1.列固定的情况,通过max+decode变换。 WITH t AS ( SELECT 1 tid,'A' typeid, 'book1' typename FROM DUAL UNION ALL SELECT 1 tid,'B' typeid, 'apple1' typename FROM DUAL UNION ALL SELECT 1 tid,'C' typeid, 'phone1' typename FROM DUAL UNION ALL SELECT 1 tid,'D' typeid, 'eye1' typename FROM ...
当表的字段个数很多的时候,取得所有字段都是null的个数 字段很少的时候,可以这么写: select count(*) from tb where a is null and b is null ... 字段很多的时候就不是很方便了,下面用动态sql实现。 DECLARE TYPE myref IS REF CURSOR; cur myref; sqlStr VARCHAR2(200); tb_name VARCHAR2(20); TYPE arrays IS TABLE OF VARCHAR2(20) INDEX BY B ...

统计相关

-- 需求:求出下表指定日期的每个TYPE_ID的新增客户和累计新增客户, -- 20110703的新增客户=去重(20110703的手机号 MINUS (20110701+20110702的手机号)) -- 20110703累计新增客户 = 去重((20110703+20110702)的手机号 MINUS 20110701的手机号)) SQL> select * from tab; DATE_ID TYPE_ID USER_PHONE -------------------- -------------------- ...
官方文档有如下说明: FIRST/LAST Functions The FIRST/LAST aggregate functions allow you to return the result of an aggregate applied over a set of rows that rank as the first or last with respect to a given order specification. FIRST/LAST lets you order on column A but return an result of an aggregate applied ...
-- 需求:求出下表的一个小时内id个数的最大值和最小值。 SQL> WITH t AS ( 2 SELECT 1 "id",TO_DATE('2011-04-27 14:05:12','yyyy-mm-dd hh24:mi:ss') c_time FROM DUAL UNION ALL 3 SELECT 2,TO_DATE('2011-04-27 15:10:42','yyyy-mm-dd hh24:mi:ss') FROM DUAL UNION ALL 4 SELECT 3,TO_DATE('2011-04-27 15:20:52',' ...

一条sql求N阶乘

-- 根据公式:log(a)(MN)=log(a)(M)+log(a)(N) SQL> SELECT POWER(10, SUM(LOG(10, LEVEL))) 2 FROM DUAL 3 CONNECT BY LEVEL <= 6; POWER(10,SUM(LOG(10,LEVEL))) ---------------------------- 720
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