Module 3 - The Relational Model: SQL

American National Standards Institute (ANSI)

An organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States.

International Organization for Standardization (ISO)

An international standard-setting body composed of representatives from various national standards organizations.

syntax

The rules by which statements in a language such as SQL must be written.

SQL (Structured Query Language)

A very popular relational data definition and manipulation language that is used in many relational DBMSs.

keywords

A word that SQL uses for defining, manipulating, and accessing databases. Also called a reserved word.

data-definition language (DDL)

The part of SQL used for creating and altering database objects.

monospaced

A font face that gives each character the same horizontal width.

CREATE TABLE

The SQL command used to describe the layout of a table. The word TABLE is followed by the name of the table to be created and then by the names and data types of the columns (fields) that comprise the table.

reserved words

A word that SQL uses for defining, manipulating, and accessing databases. Also called a keyword.

American Standard Code for Information Interchange

A standardized system for representing characters in numeric form.

BYTE

Microsoft Access data type used in the CREATE TABLE statement for a number field of BYTE size (0-255).

AUTOINCREMENT

A field whose values automatically increment by 1 as new records are added.

CHAR

A data type for a fixed-length string field, often expressed as CHAR(n), where (n) identifies the length.

AutoNumber

The Access data type for a field whose values automatically increment by 1 as new records are added.

SELECT-FROM-WHERE

The basic form of an SQL data-retrieval command.

SELECT clause

The part of an SQL SELECT command that indicates the columns to include in the query results.

logical view

Refers to the result of a query because it is not a copy of the data, but rather, a selected view of data from the underlying tables.

WHERE clause

The part of an SQL SELECT command that indicates the condition rows must satisfy to be displayed in the query results.

FROM clause

The part of an SQL SELECT command that indicates the tables in the query.

view

A particular collection of fields and records from one or more entities created for a particular user, program, or purpose; also called a query.

simple condition

A condition that involves only a single field and a single value.

qualified field names

A convention that identifies a field name by adding the table name followed by a period, followed by the field name.

AND operator

An operator that connects conditions when all the conditions must be true to select for a particular record.

calculated field

A field whose values you derive from existing fields. Also called a computed field.

OR operator

An operator that connects conditions when only one condition must be true to select a particular record.

NOT operator

An operator that reverses the result of the original condition.

concatenation

The operation of joining two or more strings or textual data into one piece of data.

alias

A field name created using the SQL AS keyword.

& operator

An operator used to combine the contents of two text fields.

built-in functions

A function such as SUM built into the SQL language.

wildcard characters

In Access SQL, the asterisk (*) is used as a wildcard to represent any collection of characters, and the question mark (?) is used to represent one character.

ORDER BY clause

The part of an SQL SELECT command that indicates a sort order.

GROUP BY clause

The SQL keywords to group records together in order to count, sum, or do other statistics on groups of records.

subquery

An SQL SELECT statement placed inside another SELECT statement and contained within parentheses so it will be evaluated first.

VALUES

The SQL keyword for listing the values in parentheses and separated by commas for each of the columns (fields) in a new record being added to the table.

INSERT command

The SQL command to add new data to a table. After the words INSERT INTO, you list the name of the table, followed by the word VALUES. Then you list the values for each of the columns in parentheses.

HAVING clause

The part of an SQL SELECT command that restricts the groups to be displayed.

INSERT INTO clause

The SQL keywords for adding a new record to a table.

DELETE command

The SQL command used to delete a table. The word DELETE is followed by a FROM clause identifying the table. Use a WHERE clause to specify a condition. Any records satisfying the condition will be deleted.