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Oracle 分组后取每组第一条数据 - 数据库(内核) - 清泛网 - 专注C/C++及内核技术
...组后取每组第一条数据Oracle 分组后取每组第一条数据的SQL如下，亲测有效：SELECT * FROM (SELECT ROW_NUMBER() OVER(PARTITION BY T field1, T Oracle 分组后取每组第一条数据的SQL如下，亲测有效：
SELECT *
FROM (SELECT ROW_NUMBER() OVER(PARTITION ...
Linq 多字段排序，二次排序 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...ordered = source.OrderByDescending( t => t.f1 ).ThenBy( t => t.f2 );类似SQL：select * from t1 order by f1 d...Linq：ordered = source.OrderByDescending( t => t.f1 ).ThenBy( t => t.f2 );
类似SQL：select * from t1 order by f1 desc ,f2 asc
这种写法里 OrderBy、ThenBy 是升序的，Ord...
SQLite 拓展查询数据表，带条件过滤 - App应用开发 - 清泛IT社区，为创新赋能！
SQLite 拓展导入，新建库、表等详见文档：https://www.fun123.cn/reference/extensions/SQLite.html
本文详细介绍一下，SQLite 的查询功能，以及带where条件的查询功能。
空表的情况下，先插入6条数据：
引入 TableView 拓展，用户展示查...
- App Inventor 2 离线版 - 清泛IT社区，为创新赋能！
数据存储 抽屉中的 微数据库 组件。键值存储，用法很简单，看下文档就行了。
如果需要 sql 数据库，使用 SQLite 拓展：拓展，拓展市场，搜索 sql
App Inventor 2 数据库方案全览：从本地存储到云端服务 - App应用开发 - 清...
...本地，App卸载就没了，且不同设备之间不能同步。
2. SQLite
- 类型：拓展组件
- 数据方案：本地存储（可导入导出库文件）
- 是否支持数据变更事件：否
- 特点：用法稍复杂，支持标准SQL，支持事务
- 业务支撑级别：中型...
SHA1 vs md5 vs SHA256: which to use for a PHP login?
... you've made it. Again this could be a disgruntled employee XSS attack or sql injection or some other attack that has nothing to do with your password encryption.
I do believe you should still encrypt but the only thing I can see the encryption does is prevent people that already have or somehow ...
Fastest way to count exact number of rows in a very large table?
...r independent solution = use the standard = COUNT(*)
There are approximate SQL Server solutions but don't use COUNT(*) = out of scope
Notes:
COUNT(1) = COUNT(*) = COUNT(PrimaryKey) just in case
Edit:
SQL Server example (1.4 billion rows, 12 columns)
SELECT COUNT(*) FROM MyBigtable WITH (NOLOCK...
Do you use source control for your database items? [closed]
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With Mysql Workbench you can have all that in a structured file(xml) that can be opened and handled with a GUI. Being xml just text, yes it can be versioning without having to type single sql sentence.
– levhi...
NOT using repository pattern, use the ORM as is (EF)
...stead of constrained to a consistent location creates the EF equivalent of SQL calls in codebehind pages. Every LINQ query is a potential maintenance point in an application, and the more there are (and the more widespread they are), the higher the maintenance costs and risks. Imagine adding a 'de...
How to edit multi-gigabyte text files? Vim doesn't work =( [closed]
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Great tip. I had a 13GB (152.000.000 lines) sql-file, and just using "split -l 1000000" then editing the one million line files where I wanted with vim worked great. Took 10 minutes just to split them. (I tried to open the original file with vim and that worked, but it...