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MySQL - why not index every field?
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The link is for MS SQL Server; this question is for MySQL
– OMG Ponies
Mar 26 '11 at 23:38
6
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css中使用变量，:root伪元素的使用 - 更多技术 - 清泛网 - 专注C/C++及内核技术
css中使用变量，:root伪元素的使用css_root前言使用css的全局变量，可以减少写很多重复代码。比如设置一个全局主题色变量，整个项目用到这个颜色的地方，都用变量设置，就很方便了。一、root伪类和css变量1 :root伪类在刚 前...
Cast int to varchar
... @JonathanSayce I'm not overly familiar with the ins & outs of MySQL and it might not use something arbitrary, but I wouldn't rely on the MySQL engine to be that smart (no offense to MySQL). In order to be sure you get the proper length, I would always explicitly provide one.
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SQL/mysql - Select distinct/UNIQUE but return all columns?
...ause the behavior on the other columns is unspecified. (The first works in MySQL, if that's what you're using.)
You could fetch the distinct fields and stick to picking a single arbitrary row each time.
On some platforms (e.g. PostgreSQL, Oracle, T-SQL) this can be done directly using window funct...
MySQL - SELECT WHERE field IN (subquery) - Extremely slow why?
...B and you only select indexed fields (and things are not too complex) than MySQL will resolve your query using only the indexes, speeding things way up.
General solution for 90% of your IN (select queries
Use this code
SELECT * FROM sometable a WHERE EXISTS (
SELECT 1 FROM sometable b
WHERE...
Redirect all to index.php using htaccess
...s almost ok.
First make sure that your .htaccess file is in your document root (the same place as index.php) or it'll only affect the sub-folder it's in (and any sub-folders within that - recursively).
Next make a slight change to your rule so it looks something like:
RewriteEngine on
RewriteCond...
Simulating group_concat MySQL function in Microsoft SQL Server 2005?
I'm trying to migrate a MySQL-based app over to Microsoft SQL Server 2005 (not by choice, but that's life).
11 Answers
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App Inventor 2 中文网原创内容 · App Inventor 2 中文网
...科普】App Inventor 2 添加超过10个屏幕会怎样？
【算法】如何计算1加到100的总和？（经典循环的写法）
【算法】App Inventor 2 算法之二分算法（Binary Search）实现，快速查找定位
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MySQL: multiple tables or one table with many columns?
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Recently I was faced with this same problem, because MySQL InnoDB tables have a relatively small length limit (~8000 bytes). In my problem table (data from very lengthy insurance forms, more than 100 columns) we have multiple varchar columns, all UTF8. So we easily filled the ~...
Two single-column indexes vs one two-column index in MySQL?
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"MySQL can use multiple-column indexes for queries that test all the columns in the index, or queries that test just the first column, the first two columns, the first three columns, and so on. If you specify the columns in th...