SQL Notes
Explore the history of SQL, from its origins in relational database theory to becoming the world
SQL is everywhere. It powers your bank transactions, your social media feeds, your online shopping, your flight bookings, and your college grade portal. But SQL was not always the dominant force it is today. It started as a research project in a single IBM lab and grew into an international standard that has survived and thrived for over five decades.
Understanding where SQL came from helps you appreciate why it works the way it does — and why it is still the undisputed king of data management despite countless attempts to replace it.
1970: Edgar F. Codd's Relational Model
In June 1970, Edgar Frank Codd, a British computer scientist working at IBM's San Jose Research Laboratory, published a paper that changed everything: "A Relational Model of Data for Large Shared Data Banks."
Codd's revolutionary ideas:
- Organize data into simple tables (relations) with rows and columns
- Separate the logical view of data from its physical storage
- Use mathematical set theory to manipulate data
- Let users specify WHAT data they want, not HOW to get it
This was radical. Instead of navigating pointer chains, you would simply describe the data you needed, and the system would figure out how to retrieve it. The paper laid the theoretical foundation for every relational database that exists today.
1973-1974: IBM's System R and SEQUEL
IBM recognized the potential of Codd's theory and launched Project System R to build a working relational database. The researchers — Donald Chamberlin and Raymond Boyce — needed a language for users to interact with this system.
They created SEQUEL (Structured English Query Language) in 1974. The design goal was brilliant: make a language that reads like English so that non-programmers could query databases.
Instead of writing complex procedural code to navigate data structures, you could write:
SELECT employee_name FROM employees WHERE department = 'Research'This was groundbreaking. For the first time, you told the computer what you wanted, not how to find it.
1977: The Name Change to SQL
SEQUEL had to be renamed to SQL (Structured Query Language) due to a trademark conflict — another company had already trademarked "SEQUEL." Despite the official name being SQL (pronounced "ess-cue-ell"), many developers to this day still say "sequel" out of habit.
Fun fact: there is an ongoing debate about the correct pronunciation. Both are acceptable, though the official ANSI standard refers to it as "ess-cue-ell."
1979: Oracle — The First Commercial SQL Database
While IBM was still developing System R internally, a small company called Relational Software Inc. (later renamed Oracle Corporation) saw the published research papers and built the first commercially available SQL database.
Oracle V2 was released in 1979, beating IBM to market. Larry Ellison and his co-founders recognized that IBM's published research described a language that enterprises desperately needed. By the time IBM released SQL/DS in 1981 and DB2 in 1983, Oracle had already established a foothold.
This sequence of events — IBM inventing the technology but a startup commercializing it first — became a famous lesson in the technology industry.
1986-1987: SQL Becomes an Official Standard
As SQL databases multiplied (Oracle, IBM DB2, Sybase, Informix), each vendor added their own extensions and variations. To ensure compatibility, standardization bodies stepped in:
- 1986: ANSI (American National Standards Institute) published the first SQL standard (SQL-86)
- 1987: ISO (International Organization for Standardization) adopted it internationally
The standard meant that learning SQL for one database would largely transfer to another. Write standard SQL, and it works on Oracle, DB2, SQL Server, and PostgreSQL with minimal changes.
Major SQL Standard Revisions
SQL-89
Minor revision of the original standard. Added integrity constraints.
SQL-92 (SQL2)
A massive update and one of the most influential versions. Added:
- JOINs (INNER, LEFT, RIGHT, FULL)
- CASE expressions
- String operations (SUBSTRING, TRIM, UPPER, LOWER)
- Date and time types
- Temporary tables
- Scroll cursors
Most SQL you write today is based on SQL-92 syntax.
SQL:1999 (SQL3)
Introduced object-relational features:
- Common Table Expressions (WITH clause / CTEs)
- Recursive queries
- Triggers
- User-defined types
- Regular expressions
- BOOLEAN data type
SQL:2003
Added:
- Window functions (ROW_NUMBER, RANK, DENSE_RANK)
- MERGE statement (upsert)
- XML support
- Sequence generators
- Auto-generated columns (IDENTITY)
SQL:2008
Added:
- TRUNCATE TABLE standard
- Enhanced MERGE
- INSTEAD OF triggers
SQL:2011
Added:
- Temporal databases (time-period tables)
- System-time versioning
SQL:2016
Added:
- JSON support
- Row pattern matching
- Polymorphic table functions
SQL:2023 (Latest)
Added:
- Enhanced JSON features
- Property graph queries
- SQL/PGQ (Property Graph Queries)
The Rise of Major SQL Databases
| Year | Database | Significance |
|---|---|---|
| 1979 | Oracle | First commercial SQL database |
| 1981 | IBM SQL/DS | IBM's first SQL product |
| 1983 | IBM DB2 | Enterprise powerhouse |
| 1987 | Sybase SQL Server | Later became Microsoft SQL Server |
| 1989 | Microsoft SQL Server | Most popular Windows database |
| 1995 | MySQL | Open-source, powered the web |
| 1996 | PostgreSQL | Advanced open-source database |
| 2000 | SQLite | Embedded database, in every smartphone |
The NoSQL Challenge (2009-2015)
Around 2009-2015, a movement called NoSQL (Not Only SQL) emerged. Companies like Google, Facebook, and Amazon argued that traditional SQL databases could not handle the massive scale of internet applications. Databases like MongoDB, Cassandra, Redis, and DynamoDB gained popularity.
NoSQL offered:
- Horizontal scaling across thousands of servers
- Flexible schemas (no rigid table structures)
- High-speed reads and writes for specific access patterns
Many predicted SQL's death. They were wrong.
SQL's Comeback: NewSQL and SQL Everywhere
By 2016, the industry realized something important: people actually love SQL's query language. The problem was never SQL itself — it was the scalability limitations of traditional databases.
The result: NewSQL databases that combine SQL's familiar syntax with modern distributed architecture:
- Google Spanner — globally distributed SQL database
- CockroachDB — distributed PostgreSQL-compatible database
- TiDB — MySQL-compatible distributed database
- Amazon Aurora — cloud-native MySQL/PostgreSQL
Even NoSQL databases added SQL-like query languages (Cassandra CQL, MongoDB's aggregation pipeline). The message was clear: developers prefer SQL.
SQL Today
SQL in 2026 is more relevant than ever:
- Every major cloud provider offers managed SQL databases (AWS RDS, Azure SQL, Google Cloud SQL)
- Data analytics relies on SQL (BigQuery, Redshift, Snowflake, Databricks)
- Business intelligence tools all use SQL as their query language
- Most programming jobs require SQL as a core skill
- AI and machine learning pipelines start with SQL for data preparation
Stack Overflow surveys consistently rank SQL among the top 3 most-used technologies, and it remains the most sought-after database skill in job postings.
Key Takeaways
- SQL was born from Edgar Codd's mathematical theory in 1970
- IBM invented it, but Oracle commercialized it first
- Standardization in 1986 made SQL portable across databases
- SQL survived the NoSQL movement and emerged stronger
- After 50+ years, SQL remains the universal language for data
SQL's longevity is no accident. Its declarative nature — telling the database what you want rather than how to get it — turned out to be a timeless design principle. Technologies come and go, but SQL endures because it solves a fundamental problem elegantly.
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