Relational Databases and SQL Flashcards

Flashcards for Relational Databases and SQL lecture.

Primary Key

A unique identifier for a record within a table.

Foreign Key

Used to relate tables in a relational database; refers to the primary key in another table.

Null Value

A value in a cell that means unknown or inapplicable.

Default Value

The value used when a value is not provided for a column during row insertion; defined during table creation.

Query

A SELECT statement that does not modify user data.

Action Query

INSERT, DELETE, or UPDATE statements.

Result Set

What is returned from a SELECT statement; includes a set of selected rows and columns.

Clause

Part of a SQL statement, e.g., SELECT clause, FROM clause, etc.

SQL Script

A text file that contains a number of SQL statements; in Oracle, the default extension name is .sql.

VARCHAR2(n)

Variable-length sequence of ASCII characters (Oracle data type).

NUMBER(p,s)

Integer and decimal numbers that contain an exact value (Oracle data type).

DATE

Date and time values (Oracle data type).

CHAR(n)

Fixed-length sequence of ASCII characters (Oracle data type).

FLOAT(p)

Floating-point numbers that contain an approximate value (Oracle data type).

SQL Variant

The implementation of a specific database vendor with possible extensions to standard SQL.

DML

Data Manipulation Language (INSERT, DELETE, UPDATE, SELECT)

DDL

Data Definition Language (CREATE, ALTER, DROP)

DCL

Data Control Language (GRANT, REVOKE)

TCL

Transaction Control Language (COMMIT, ROLLBACK)

PL/SQL

Procedural Language extension to SQL, including control structures and error handling.

Embedded SQL

SQL commands embedded inside a programming language like Java.