> For the complete documentation index, see [llms.txt](https://harshityadav95.gitbook.io/system-design/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://harshityadav95.gitbook.io/system-design/sql.md). # SQL ### Traditional way of storing the data before the database * Sequential Master update in a single file and sort timely for the faster update, done on magnetic data drives * Random access data , stored in the disk drives and faster access but sorting not feasible , disks were easy to do update and read * Structured query language came as a standard to read and interact with database from different vendors * SQL is most powerful non procedural language ### Structure of Database Sheet ![](https://2828957172-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MFPF_rDo5w1k3YcJibC%2Fsync%2Fe3738ceb704a8a50b66f8e022892e25438ecc0a7.png?generation=1624104627036583\&alt=media) ### [Creating the SQL database standard](https://d3c33hcgiwev3.cloudfront.net/0gemkpv2TNOHppKb9tzTtw_707f99e7a6394059bf9d7db120115550_2014-08-SQL-Fong-Copyright-IEEE.pdf?Expires=1624147200\&Signature=VMDF0t-ZMQcGneJayVwF~YjvI2jTrHLbaNnU4WPDW8FzPrhxD-~qNPgtpEbz0t6cBhwVMrkHBGF~xQ4zs4P1eQEo7iznxsecmJAYHyuhoCoSETumVbdd6V-kLNomCFKXMOWT2Bw4NYeWYgYzaIR-5WsNvgbesstOxQpDc1H4m8s_\&Key-Pair-Id=APKAJLTNE6QMUY6HBC5A) ### Interactive Learning * ### Reference * [Anomaly Detection using simple SQL](https://hakibenita.com/sql-anomaly-detection) * [Speeding up SQL queries by orders of magnitude using UNION](https://www.foxhound.systems/blog/sql-performance-with-union/) * [**Practical SQL for Data Analysis**](https://hakibenita.com/sql-for-data-analysis) * [HOW TO INTERPRET POSTGRESQL EXPLAIN ANALYZE OUTPUT](https://www.cybertec-postgresql.com/en/how-to-interpret-postgresql-explain-analyze-output/) * [Thinking in Events: From Databases to Distributed Collaboration Software](https://martin.kleppmann.com/2021/07/02/debs-keynote-thinking-in-events.html) * [Recursion in SQL](https://medium.com/swlh/recursion-in-sql-explained-graphically-679f6a0f143b)