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Updating MySQL primary key
...-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f2341576%2fupdating-mysql-primary-key%23new-answer', 'question_page');
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Are there disadvantages to using a generic varchar(255) for all text-based fields?
...ould always store 255 characters.
But since you tagged this question with MySQL, I'll mention a MySQL-specific tip: as rows are copied from the storage engine layer to the SQL layer, VARCHAR fields are converted to CHAR to gain the advantage of working with fixed-width rows. So the strings in mem...
STL 算法 - C/C++ - 清泛网 - 专注C/C++及内核技术
...合算法(4个)
函数名
头文件
函数功能
set_union
<algorithm>
构造一个有序序列，包含两个序列中所有的不重复元素。重载版本使用自定义的比较操作
函数原形
template<class InIt1, class InIt2, class OutIt> OutIt set_union...
NASM x86汇编入门指南 - C/C++ - 清泛网 - 专注C/C++及内核技术
...wide Assembler)汇编编译工具
3.1 为什么使用NASM？
3.2 如何安装NASM？
4. Linux汇编介绍
4.1 DOS和Linux汇编主要不同的地方
4.2 一个汇编程序的组成
4.3 linux系统调用
4.3.1 阅读参考手册
4.4 “Hello World!”汇编...
What's the best way to join on the same table twice?
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You could use UNION to combine two joins:
SELECT Table1.PhoneNumber1 as PhoneNumber, Table2.SomeOtherField as OtherField
FROM Table1
JOIN Table2
ON Table1.PhoneNumber1 = Table2.PhoneNumber
UNION
SELECT Table1.PhoneNumber2 as Phon...
MySQL Select all columns from one table and some from another table
...mns from one table and just some columns from another table using JOIN? In MySQL.
4 Answers
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MySQL foreign key constraints, cascade delete
... When creating the tables, you need to specify InnoDB or another MySQL engine that's capable of CASCADE operations. Otherwise the MySQL default, MyISAM, will be used and MyISAM does not support CASCADE operations. To do this, just add ENGINE InnoDB before the last ;.
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Table is marked as crashed and should be repaired
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Run this from your server's command line:
mysqlcheck --repair --all-databases
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MySQL IF NOT NULL, then display 1, else display 0
... NOT NULL) AS addressexists
This works because TRUE is displayed as 1 in MySQL and FALSE as 0.
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MySQL Results as comma separated list
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The intent is fine and MySQL will allow this, but be careful (generally) with your use of GROUP BY. The items in the select list need to be valid aggregates in the context of the GROUP BY clause. In this case, p.name is not strictly valid. Any d...