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Reserved words in SQL and related products In SQL:2023 [3] In IBM Db2 13 [4] In Mimer SQL 11.0 [5] In MySQL 8.0 [6] In Oracle Database 23c [7] In PostgreSQL 16 [1] In Microsoft SQL Server 2022 [2]
In SQL, the TRUNCATE TABLE statement is a data manipulation language (DML) [1] operation that deletes all rows of a table without causing a triggered action. The result of this operation quickly removes all data from a table, typically bypassing a number of integrity enforcing mechanisms.
DELETE requires a shared table lock; Triggers fire; DELETE can be used in the case of: database link; DELETE returns the number of records deleted; Transaction log - DELETE needs to read records, check constraints, update block, update indexes, and generate redo / undo. All of this takes time, hence it takes time much longer than with TRUNCATE
Codd's twelve rules [1] are a set of thirteen rules (numbered zero to twelve) proposed by Edgar F. Codd, a pioneer of the relational model for databases, designed to define what is required from a database management system in order for it to be considered relational, i.e., a relational database management system (RDBMS).
Many computer systems measure time and date using Unix time, an international standard for digital timekeeping. Unix time is defined as the number of seconds elapsed since 00:00:00 UTC on 1 January 1970 (an arbitrarily chosen time based on the creation of the first Unix system ), which has been dubbed the Unix epoch .
Major DBMSs, including SQLite, [5] MySQL, [6] Oracle, [7] IBM Db2, [8] Microsoft SQL Server [9] and PostgreSQL [10] support prepared statements. Prepared statements are normally executed through a non-SQL binary protocol for efficiency and protection from SQL injection, but with some DBMSs such as MySQL prepared statements are also available using a SQL syntax for debugging purposes.
Simpler SQL functions can get expanded inline into the calling (SQL) query, which saves function call overhead and allows the query optimizer to "see inside" the function. Procedural Language/PostgreSQL ( PL/pgSQL ) (safe), which resembles Oracle's Procedural Language for SQL ( PL/SQL ) procedural language and SQL/Persistent Stored Modules ...
ISO-8859-1, Windows-1252, and the original 7-bit ASCII were the most common character encoding methods on the World Wide Web until 2008, when UTF-8 overtook them. [57] ISO/IEC 4873 introduced 32 additional control codes defined in the 80–9F hexadecimal range, as part of extending the 7-bit ASCII encoding to become an 8-bit system. [63]