MYSQL处理百万级以上的数据提高查询速度的方法,其它数据库应用也有一定的参考价值:1.应尽量避免在 where 子句中使用!=或操作符,否则将引擎放弃使用索引而进行全表扫描。2.对查询进行优化,应尽量避免全表扫描,首先应考虑在 where 及 order by 涉及的列上建立索引。3.应尽量避免在...
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数据库 时间:
2014-07-16 23:25:20
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272
DescriptionFor the daily milking, Farmer John'sNcows (1 ≤N≤ 50,000) always line up in the same order. One day Farmer John decides to organize a game o...
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其他好文 时间:
2014-06-28 09:32:17
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200
Problem :It can be seen that the number, 125874, and its double, 251748, contain exactly the same digits, but in a different order.Find the smallest positive integer, x, such that 2x, 3x, 4x, 5x, and ...
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其他好文 时间:
2014-06-28 08:13:17
阅读次数:
249
ORA-02287: 此处不允许序号
insert into gls_vchitem
(viid,
yr,
km)
select gls_vchitem_seq.nextval as viid,
yr,
km
from gls_vchitem_tmp
order by km;
不能有order by 或group by...
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其他好文 时间:
2014-06-28 08:12:41
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257
Given an array withnobjects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order red, wh...
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其他好文 时间:
2014-06-27 12:55:53
阅读次数:
235
You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single ...
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其他好文 时间:
2014-06-27 12:21:24
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215
1.查询数据库是否有等待select * from resource_queues where node_name=(select node_name from nodes order by node_name limit 1) order by queue_entry_timestamp desc...
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数据库 时间:
2014-06-27 12:03:53
阅读次数:
680
Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.
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其他好文 时间:
2014-06-27 11:51:13
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193
Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.
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其他好文 时间:
2014-06-27 11:40:49
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156
题目:You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a sing...
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其他好文 时间:
2014-06-27 11:38:12
阅读次数:
207