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In computing, SQL injection is a code injection technique used to attack data-driven applications, in which malicious SQL statements are inserted into an entry field for execution (e.g. to dump the database contents to the attacker). [1][2] SQL injection must exploit a security vulnerability in an application's software, for example, when user ...
Prepared statement. In database management systems (DBMS), a prepared statement, parameterized statement, or 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.
Projection (relational algebra) In relational algebra, a projection is a unary operation written as , where is a relation and are attribute names. Its result is defined as the set obtained when the components of the tuples in are restricted to the set – it discards (or excludes) the other attributes. [1]
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 Teradata 15 [ 8 ]
Relational database. A relational database (RDB[1]) is a database based on the relational model of data, as proposed by E. F. Codd in 1970. [2] A database management system used to maintain relational databases is a relational database management system (RDBMS). Many relational database systems are equipped with the option of using SQL ...
The nested set model is a technique for representing nested set collections (also known as trees or hierarchies) in relational databases.. It is based on Nested Intervals, that "are immune to hierarchy reorganization problem, and allow answering ancestor path hierarchical queries algorithmically — without accessing the stored hierarchy relation".
An attacker thereby "injects" code into the program, changing the course of its execution. The result of successful code injection can have major consequences, for example, by allowing computer viruses or computer worms to propagate. Code injection vulnerabilities occur when an application sends untrusted data to an interpreter.
PostgreSQL, MySQL and Oracle support natural joins; Microsoft T-SQL and IBM DB2 do not. The columns used in the join are implicit so the join code does not show which columns are expected, and a change in column names may change the results. In the SQL:2011 standard, natural joins are part of the optional F401, "Extended joined table", package.