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SQL includes operators and functions for calculating values on stored values. SQL allows the use of expressions in the select list to project data, as in the following example, which returns a list of books that cost more than 100.00 with an additional sales_tax column containing a sales tax figure calculated at 6% of the price.
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...
A data control language (DCL) is a syntax similar to a computer programming language used to control access to data stored in a database (authorization). In particular, it is a component of Structured Query Language (SQL).
MySQL (/ ˌ m aɪ ˌ ɛ s ˌ k juː ˈ ɛ l /) [6] is an open-source relational database management system (RDBMS). [6] [7] Its name is a combination of "My", the name of co-founder Michael Widenius's daughter My, [1] and "SQL", the acronym for Structured Query Language.
In this case, if the transaction's timestamp is after the object's read timestamp, the read timestamp is set to the transaction's timestamp. If a transaction wants to write to an object, but the transaction started before the object's read timestamp it means that something has had a look at the object, and we assume it took a copy of the object ...
The SQL SELECT statement returns a result set of rows, from one or more tables. [1] [2] A SELECT statement retrieves zero or more rows from one or more database tables or database views. In most applications, SELECT is the most commonly used data manipulation language (DML) command.
In database management systems (DBMS), a prepared statement, parameterized statement, (not to be confused with parameterized query) is a feature where the database pre-compiles SQL code and stores the results, separating it from data. Benefits of prepared statements are: [1] efficiency, because they can be used repeatedly without re-compiling
In SQL, the data manipulation language comprises the SQL-data change statements, [3] which modify stored data but not the schema or database objects. Manipulation of persistent database objects, e.g., tables or stored procedures, via the SQL schema statements, [3] rather than the data stored within them, is considered to be part of a separate data definition language (DDL).