大约有 40,000 项符合查询结果（耗时：0.0307秒） [XML]
What is the most efficient/elegant way to parse a flat table into a tree?
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Now that MySQL 8.0 supports recursive queries, we can say that all popular SQL databases support recursive queries in standard syntax.
WITH RECURSIVE MyTree AS (
SELECT * FROM MyTable WHERE ParentId IS NULL
UNION ALL
SELE...
淘宝网采用什么技术架构来实现网站高负载的 - 更多技术 - 清泛网 - 专注C/C...
...淘宝目前的一些底层技术框架以及自己的一些感触来说说如何构建一个可 伸缩，高性能，高可用性的分布式互联网应用。时间过得很快，来淘宝已经两个月了，在这两个月的时间里，自己也感受颇深。下面就结合淘宝目前的一...
二维码的生成细节及原理 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...是分成不同的Block，然后对各个Block进行纠错编码，对于如何分组，我们可以查看QR Code Spec的第33页到44页的Table-13到Table-22的定义表。注意最后两列：
Number of Error Code Correction Blocks ：需要分多少个块。
Error Correction Code Per Blo...
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
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So, you have a
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
java.net.ConnectException: Connection refused
I'm quoting from this answer which also contains a step-by-step MySQL+JDBC tutorial:
If yo...
How do I import CSV file into a MySQL table?
...unnormalized events-diary CSV from a client that I'm trying to load into a MySQL table so that I can refactor into a sane format. I created a table called 'CSVImport' that has one field for every column of the CSV file. The CSV contains 99 columns , so this was a hard enough task in itself:
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How to shrink/purge ibdata1 file in MySQL
I am using MySQL in localhost as a "query tool" for performing statistics in R, that is, everytime I run a R script, I create a new database (A), create a new table (B), import the data into B, submit a query to get what I need, and then I drop B and drop A.
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MySQL: Enable LOAD DATA LOCAL INFILE
I'm running Mysql 5.5 on Ubuntu 12 LTS. How should I enable LOAD DATA LOCAL INFILE in my.cnf?
18 Answers
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What does the PHP error message “Notice: Use of undefined constant” mean?
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You should quote your array keys:
$department = mysql_real_escape_string($_POST['department']);
$name = mysql_real_escape_string($_POST['name']);
$email = mysql_real_escape_string($_POST['email']);
$message = mysql_real_escape_string($_POST['message']);
As is, it was loo...
淘宝应对双\"11\"的技术架构分析 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...余度。
大量使用缓存的最大问题就是数据一致性问题。如何保证底层数据的变化在尽可能短的时间内体现给最终用户呢？这一定是一个系统化的工程，尤其对于分层较多的系统来说。
图9 缓存控制体系
图9向我们展示了数据...
搭建高可用mongodb集群（三）—— 深入副本集内部机制 - 大数据 & AI - 清...
...着副本集的问题来看吧！
副本集故障转移，主节点是如何选举的？能否手动干涉下架某一台主节点。
官方说副本集数量最好是奇数，为什么？
mongodb副本集是如何同步的？如果同步不及时会出现什么情况？会不会出现不一致...