17 Facts About SQL

1.

SQL is a domain-specific language used in programming and designed for managing data held in a relational database management system, or for stream processing in a relational data stream management system.

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2.

The scope of SQL includes data query, data manipulation, data definition, and data access control.

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3.

SQL was one of the first commercial languages to use Edgar F Codd's relational model.

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4.

SQL became a standard of the American National Standards Institute in 1986 and of the International Organization for Standardization in 1987.

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5.

SQL was initially developed at IBM by Donald D Chamberlin and Raymond F Boyce after learning about the relational model from Edgar F Codd in the early 1970s.

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6.

The name SEQUEL was later changed to SQL because "SEQUEL" was a trademark of the UK-based Hawker Siddeley Dynamics Engineering Limited company.

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7.

The label SQL later became the acronym for Structured Query Language.

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8.

SQL is designed for a specific purpose: to query data contained in a relational database.

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9.

SQL is a set-based, declarative programming language, not an imperative programming language like C or BASIC.

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10.

However, extensions to Standard SQL add procedural programming language functionality, such as control-of-flow constructs.

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11.

SQL implementations are incompatible between vendors and do not necessarily completely follow standards.

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12.

The folding of unquoted names to lower case in PostgreSQL is incompatible with the SQL standard, which says that unquoted names should be folded to upper case.

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13.

SQL was adopted as a standard by the ANSI in 1986 as SQL-86 and the ISO in 1987.

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14.

SQL standard is divided into 10 parts, but with gaps in the numbering due to the withdrawal of outdated parts.

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15.

SQL deviates in several ways from its theoretical foundation, the relational model and its tuple calculus.

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16.

Critics argue that SQL should be replaced with a language that returns strictly to the original foundation: for example, see The Third Manifesto.

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17.

The concept of Nulls enforces the 3-valued-logic in SQL, which is a concrete implementation of the general 3-valued logic.

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