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DBD (DataBase Driver) modules serve as plug-ins to DBI, allowing programmers to use near-database-independent SQL code in their applications. Programmers can also use the DBI and DBD modules indirectly using one of the object-relational mappers available for Perl, such as DBIx::Class, for more database-independent code with no need to write SQL.
The MySQLi Extension (MySQL Improved) is a relational database driver used in the PHP scripting language to provide an interface with MySQL protocol compatible databases (MariaDB, MySQL, Percona Server, TiDB). [1] [2] There are three main API options when considering connecting to a MySQL database server: PHP's MySQL Extension; PHP's MySQLi ...
The web server or database management system also varies. LEMP is a version where Apache has been replaced with the more lightweight web server Nginx. [6] A version where MySQL has been replaced by PostgreSQL is called LAPP, or sometimes by keeping the original acronym, LAMP (Linux / Apache / Middleware (Perl, PHP, Python, Ruby) / PostgreSQL). [7]
Pattern matching – regex is integrated into perl. Stream editing – Database manipulation – Shell scripting – perl is good for writing programs in the form of a series of commands to be run by the Unix shell, a command line interpreter. Such programs are called "scripts". In this regard, perl is considered to be a scripting language.
In early versions of Perl, database interfaces were created by relinking the interpreter with a client-side database library. This was sufficiently difficult that it was done for only a few of the most-important and most widely used databases, and it restricted the resulting perl executable to using just one database interface at a time. [135]
Some - can only reverse engineer the entire database at once and drops any user modifications to the diagram (can't "refresh" the diagram to match the database) Forward engineering - the ability to update the database schema with changes made to its entities and relationships via the ER diagram visual designer Yes - can update user-selected ...
A function is a subprogram written to perform certain computations. A scalar function returns only one value (or NULL), whereas a table function returns a (relational) table comprising zero or more rows, each row with one or more columns. Functions must return a value (using the RETURN keyword), but for stored procedures this is not mandatory.
An example of a database that has not enforced referential integrity. In this example, there is a foreign key (artist_id) value in the album table that references a non-existent artist — in other words there is a foreign key value with no corresponding primary key value in the referenced table.