We all know that DBMS (database management system) is used to store (a massive amount of) data. However, have you ever wondered how is data stored in DBMS? In this post, we will focus on data storage in RDBMS, the most traditional relational database systems.Physical StorageData can be stored in many different kinds of medium or devices, from the fastest but costy registers to the slow but cheap hard drives, or even magnetic tapes. Nowadays, IaaS providers such as AWS even provides services such as S3 Glacier as a low-cost archiving storage solution. The...

In a previous post, we discussed how the various relational operators are implemented in relational database systems. If you have read that post, you probably still remember that there are a few alternative implementations for every operator. Thus, how should RDBMS determine which algorithm (or implementation) to use?Obviously, to optimize the performance for any query, RDBMS has to select the correct the algorithm based on the query. It would not be desirable to always use the same algorithm. Also, SQL is a declarative language (i.e., as a programmer we only declare what we want to ...

Updated 2011-11-28: Added reference to the walkthrough of using LocalDB in Visual Studio 2010 and to the new LocalDB Installer.Updated 2011-11-02: Added reference to .NET Framework 4 support for LocalDB in the Q&A section.IntroductionIt gives me great pleasure to introduce a new version of SQL Express called SQL Express LocalDB.LocalDB is created specifically for developers. It is very easy to install and requires no management, yet it offers the same T-SQL language, programming surface and client-side providers as the regular SQL Server Express. In effect the developers that target SQL Se...

IntroductionBefore you start reading this article let me confirm that I am not a guru in database designing. The below 11 points which are listed are points which I have learnt via projects, my own experiences and my own reading. I personally think it has helped me a lot when it comes to DB designing. Any criticism welcome.The reason why I am writing a full blown article is, when developers sit for designing a database they tend to follow the three normal forms like a silver bullet. They tend to think normalization is the only way of designing. Due this mind set they sometimes hit road blocks ...

New features are added with every release of SQL Server and as a result, some features get removed or deprecated. Deprecated features are features that are still operational (for backward compatibility) but will be removed in a future version. Deprecated features can be of two types: those that will be deprecated in a future version and those that will be deprecated in the next version.In this article, we will explore how to track deprecated code and correct it. I will also share our observations when we performed the same operation on a live production database. Please feel free to ...

Some simple introduction to the SQLite function interfaces. First let's check some error codes defined in SQLite3 (They are in SQLite3.h file in the SQLite installation).#define SQLITE_OK           0   /* Successful result */  /* beginning-of-error-codes */  #define SQLITE_ERROR        1   /* SQL error or missing database */  #define SQLITE_INTERNAL     2   /* Internal logic error in SQLite */  #define SQLITE_PERM    &nbs...

ClickHouse is a high-performance open-source columnar database management system developed by Yandex. Here are some of the key features of ClickHouse:Columnar storage: ClickHouse uses a columnar storage format, which allows it to efficiently store and retrieve data by column, rather than by row. This results in much faster query performance, especially for analytical and aggregate queries.Real-time data processing: ClickHouse is designed to handle real-time data processing and can handle billions of rows of data with sub-second query times.Massively scalable: ClickHouse can scale to handle mas...

整理了一下，希望对大家有用SQL语句大全  --语 句 功 能--数据操作SELECT --从数据库表中检索数据行和列INSERT --向数据库表添加新数据行DELETE --从数据库表中删除数据行UPDATE --更新数据库表中的数据--数据定义CREATE TABLE --创建一个数据库�...