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Flashcards in Exam 1 Deck (98):
0

Database = LOST 2 STD

Database = logical structure to store data

1

Database Management System = SOFT CRIN WTDB

Database Management System: software to create and interact with database.

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Each byte = CH BBB I

Each byte = character that is the basic building block of information.

3

Record = CFSE & RPD

Record = collection of fields for specific entity and row in the physical database

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Relational Database Management System: SP CRDB ENT MAN RTD

Software to create the database and allows you to enter, manipulate, and retrieve data.

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SELECT statements are: ST 2 RT DFDB

Used to retrieve data from the database

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Syntax gives the BS ORU 4 CO

Gives the basic structure or rules for a command

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SELECT clause identifies

Columns

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FROM clause identifies

Tables

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Each clause begins with a:

Keyword

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To execute SQL statements use:

Semicolon or slash

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To select all data in a table:

Substitute an asterisk for the column names in a SELECT clause

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To select one column from a table:

Enter column name in SELECT clause

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To select multiple columns from a table:

Separate column names with a comma

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Enclose in double quotation marks when:

It contains blank spaces, special symbols or to retain case

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Arithmetic Operations are:

Executed left to right

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Multiplication and division are solved:

First with arithmetic operations

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Addition and subtraction are solved:

Last with arithmetic operations

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You override arithmetic operations with:

Parentheses

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To suppress duplicates:

Enter DISTINCT or UNIQUE after SELECT keyword

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Field= GRC

Field= group of related characters

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Field= ACE

Attribute or character of an entity

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Field= CPD

Column in the physical database

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File= GRSE

Group of records about the same type of entity

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Relational database = COR

Collection of relations

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Rows= DAE

Contain data about an entity

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Columns= DAAE

Data about attributes of the entity

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Cells= THSV

Cells of the table hold a single value

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Character = BUD & L, N, SS

Basic unit of data and can be a letter, #, or special symbol

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Bit= SDU

Smallest data unit

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Byte= 8FB

Few bits (usually 8)

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Database components:

Field, record, and file

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Relation:

Two-dimensional table

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Each column has:

A unique name

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The order of the columns is:

Unimportant

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The order of the rows is:

Unimportant

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No two rows can be:

Identical

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Table =

File

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File =

Relation

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Row =

Record

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Record =

Tuple

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Column =

Field

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Field =

Attribute

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Normalization:

Used to reduce or control data redundancy

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Primary key:

Field that serves to uniquely identify each record in a table

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Candidate key:

Any field that could be used as the primary key

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Surrogate key:

The records primary key identifier when no suitable primary key exists

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Foreign key:

A field in a table that is a primary key in another table

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Composite key:

A unique key that you create by combining two or more fields

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Partial dependency:

A column that is only dependent on a portion of the primary key

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1NF=

Eliminate repeating groups and identify primary key

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2NF=

Table is in 1NF and partial dependencies are eliminated

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3NF=

Table is in 2NF and transitive dependencies are eliminated

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Tables are linked through:

A common field

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Common field=

A primary key in one table and a foreign key in the other table

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SQL=

A data sub language that has constructs for defining and processing a database

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Data definition language is used to:

Define database structures

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Data Manipulation Language is used to:

Query and update data

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Concatenation:

Are two vertical bars and can combine data with string literal

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Concatenation allows use of:

Column alias

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WHERE clause is used to:

Retrieve rows based on a stated condition

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WHERE clause requires:

Column name, comparison operator, and value or column for comparison

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WHERE clause is:

Case sensitive

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List WHERE clause after:

FROM clause

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In WHERE clause enclose non-numeric data in:

Single quotes

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Comparison Operators:

Indicates how the data should relate to the given search value

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The default SQL format for dates is:

DD-MON-YY

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>

Greater than

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<

Less than

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<>

Not equal to

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<=

Less than or equal to

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>=

Greater than or equal to

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Math comparison operators may work with:

Text as well as numbers

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BETWEEN... AND Operator

To find values in a specified range

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IN Operator

Values are separated by commas and list must be in parentheses

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LIKE Operator

Performs pattern searches

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Logical operators:

Used to combing conditions

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Not

Reverses meaning

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And

Both conditions must be true

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Or

At least one condition must be true

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ORDER BY Clause

Presents data in sorted order

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Use DESC keyword to:

Override column default

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In ascending order, values will be listed in the following sequence:

Numeric values, character values, NULL values

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Secondary sort may be used to:

Sort multiple exact matches

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Joins are used to:

Link tables and reconstruct data in a relational database

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Joins can be created through:

Using the WHERE clause or using the JOIN keyword in the FROM clause

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Cross Join is created by omitting joining condition in the:

WHERE clause or through CROSS JOIN keywords in the FROM clause

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Equality Join:

Links rows through equivalent data in a common field that exists in both tables

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Equality join is also called:

Equijoins, natural join, inner joins, or simple joins

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Table Alias:

A temporary name that works like a column alias

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If a table alias is assigned to a table:

It must be used any time the table is referenced in the SQL statement

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Use NATURAL JOIN when:

Tables have one column in common

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Use JOIN... USING when:

Tables have more than one column in common

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Use JOIN... ON when:

A condition is needed to specify a relationship other than equivalency

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Using the JOIN keyword frees the:

WHERE clause for exclusive use in restricting rows

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Self Joins:

Used to link a table to itself

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Outer Joins

Used to include rows that do not have a match in the other table

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Set Operators

Used to combine the results of two or more SELECT statements