Introduction to Relational Databases and SQL

Flashcards for Relational Databases and SQL lecture.

Foreign Key

Used to relate tables in a relational database; consists of one or multiple columns in a table that refer 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.

VARCHAR2(n)

Variable-length sequence of ASCII characters (e.g., VARCHAR2(20)).

NUMBER(p,s)

Integer and decimal numbers that contain an exact value (e.g., NUMBER(5), NUMBER(10, 2)).

DATE

Date and time values.

CHAR(n)

Fixed-length sequence of ASCII characters (e.g., CHAR(2)).

FLOAT(p)

Floating-point numbers that contain an approximate value; for very large, very small numbers.

Query

SELECT statement that does not modify user data.

Action Query

INSERT, DELETE, 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

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

DML

Data Manipulation Language: INSERT, DELETE, UPDATE, SELECT

DDL

Data Definition Language: CREATE, ALTER, DROP TABLE, USER, etc.

DCL

Data Control Language: GRANT, REVOKE

Transaction Control Language

COMMIT, ROLLBACK

PL/SQL

Procedural Language extension to SQL with extensions like control structures and error handling.

Embedded SQL

SQL commands embedded inside a programming language like Java.