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MySQL, better to insert NULL or empty string?
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Better to Insert NULL for consistency in your database in MySQL. Foreign keys can be stored as NULL but NOT as empty strings.
You will have issues with an empty string in the constraints.
You may have to insert a fake record with a unique empty string to satisfy a Foreign Key cons...
MySQL join with where clause
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Unknown Column In Where Clause
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See the following MySQL manual page: http://dev.mysql.com/doc/refman/5.0/en/select.html
"A select_expr can be given an alias
using AS alias_name. The alias is used
as the expression's column name and
can be used in GROUP BY, ORDER BY...
How can I sanitize user input with PHP?
...of that language. For example, if you embed a string in some SQL targeting MySQL, you must escape the string with MySQL's function for this purpose (mysqli_real_escape_string). (Or, in case of databases, using prepared statements are a better approach, when possible.)
Another example is HTML: If yo...
SQL Group By with an Order By
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In all versions of MySQL, simply alias the aggregate in the SELECT list, and order by the alias:
SELECT COUNT(id) AS theCount, `Tag` from `images-tags`
GROUP BY `Tag`
ORDER BY theCount DESC
LIMIT 20
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Difference between scaling horizontally and vertically for databases [closed]
...MongoDB, Google Cloud Spanner .. and a good example of vertical scaling is MySQL - Amazon RDS (The cloud version of MySQL). It provides an easy way to scale vertically by switching from small to bigger machines. This process often involves downtime.
In-Memory Data Grids such as GigaSpaces XAP, Coher...
Insert auto increment primary key to existing table
...reated the row with auto-increment and must retrieve it by id immediately, MySQL offers LAST_INSERT_ID() for that value SELECT * FROM table_name WHERE id = LAST_INSERT_ID() and most programming language APIs offer some function/method to return that value in the application code.
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一个科技公司只是碰巧卖起了披萨？ - 资讯 - 清泛网 - 专注C/C++及内核技术
...执行送餐，最高时速可达每小时12.5公里。顾客可以通过密码解锁，打开DRU自助取餐。
2016年4月，达美乐又推出新App一键下单——“一键”的意思是：“点开App，而不需任何其他操作”，10秒内倒计时确认非误操作，就会完成下...
Laravel Eloquent ORM Transactions
...t ORM is quite nice, though I'm wondering if there is an easy way to setup MySQL transactions using innoDB in the same fashion as PDO, or if I would have to extend the ORM to make this possible?
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Is there a good reason I see VARCHAR(255) used so often (as opposed to another length)?
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@CharlesBretana: By "fake UTF-8" I mean MySQL's "utf8" encoding, which as I mentioned reserves (and is limited to) 3 bytes per character. This isn't a very good version of UTF-8; if you want decent UTF-8 in MySQL, you have to use its "utf8mb4" encoding. But peopl...