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Error 1046 No database Selected, how to resolve?
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You need to tell MySQL which database to use:
USE database_name;
before you create a table.
In case the database does not exist, you need to create it as:
CREATE DATABASE database_name;
followed by:
USE database_name;
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Simple way to calculate median with MySQL
...the simplest (and hopefully not too slow) way to calculate the median with MySQL? I've used AVG(x) for finding the mean, but I'm having a hard time finding a simple way of calculating the median. For now, I'm returning all the rows to PHP, doing a sort, and then picking the middle row, but surely ...
Which ORM should I use for Node.js and MySQL? [closed]
I'm rewriting a project to use Node.js. I'd like to keep using MySQL as the DB (even though I don't mind rewriting the schema).
I'm looking for a simple-to-use, reasonable-performance ORM, which supports caching, many-to-one and many-to-many relations.
From the MySQL ORMs I could find, persistencej...
How do I show a MySQL warning that just happened?
I just ran a simple MySQL CREATE TABLE statement that produced the line
3 Answers
3
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内存管理内幕：动态分配的选择、折衷和实现 - C/C++ - 清泛网 - 专注C/C++及内核技术
...点是 C 语言，但同样也适用于其他语言。文中将为您提供如何管理内存的细节，然后将进一步展示如何手工管理内存，如何使用引用计数或者内存池来半手工地管理内存， 以及如何使用垃圾收集自动管理内存。为什么必须管理...
MySQL INSERT INTO table VALUES.. vs INSERT INTO table SET
...ll, both syntaxes are equivalent. The first is SQL standard, the second is MySQL's extension.
So they should be exactly equivalent performance wise.
http://dev.mysql.com/doc/refman/5.6/en/insert.html says:
INSERT inserts new rows into an existing table. The INSERT ... VALUES and INSERT ... SET...
Create a CSV File for a user in PHP
I have data in a MySQL database. I am sending the user a URL to get their data out as a CSV file.
19 Answers
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tinyxml XML解析库下载（tinyxml2.h 和 tinyxml2.cpp） - 源码下载 - 清泛...
...int SIZE >
class MemPoolT : public MemPool
{
public:
MemPoolT() : _root(0), _currentAllocs(0), _nAllocs(0), _maxAllocs(0), _nUntracked(0) {}
~MemPoolT() {
// Delete the blocks.
for( int i=0; i<_blockPtrs.Size(); ++i ) {
delete _blockPtrs[i];
}
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How to install trusted CA certificate on Android device?
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Prior to Android KitKat you have to root your device to install new certificates.
From Android KitKat (4.0) up to Nougat (7.0) it's possible and easy. I was able to install the Charles Web Debbuging Proxy cert on my un-rooted device and successfully sniff SSL ...
Is it a good idea to index datetime field in mysql?
...etime clause to select data. Is it a good idea to index datetime fields in mysql database?
2 Answers
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