Database Design Fundamentals

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Questions and Answers

This ensures that the column always has a ______,

value

Which can be useful for maintaining data ______ and enforcing business rules.

integrity

This process is important for ______ business rules.

enforcing

A defined value in the column ensures ______ in the dataset.

consistency Signup and view all the answers

Data ______ is essential for creating reliable reports.

integrity Signup and view all the answers

To create a unique constraint, specify the column to be ______.

constrained Signup and view all the answers

The unique constraint command uses the format `UNIQUE (______)`.

column_name Signup and view all the answers

An example of adding a unique constraint would be `ALTER TABLE person ADD CONSTRAINT phone_unique UNIQUE(______)`.

phone Signup and view all the answers

The command adds a unique constraint named `phone_unique` to the ______ column.

phone Signup and view all the answers

In SQL, a unique constraint prevents duplicate values in a specified ______.

column Signup and view all the answers

The ______ keyword defines a unique constraint.

unique Signup and view all the answers

Using unique constraints helps prevent ______ data and maintain data integrity.

duplicate Signup and view all the answers

It is important to carefully consider the unique ______ you create for a table.

constraints Signup and view all the answers

Unique constraints help maintain data ______.

integrity Signup and view all the answers

Creating unique constraints can prevent issues related to ______ data.

duplicate Signup and view all the answers

The `INSERT` command is used to add new rows to a ______.

table Signup and view all the answers

The syntax for the `INSERT` command includes `INSERT INTO ______ (column1, column2, ...)`.

table_name Signup and view all the answers

In the example, the new row is inserted into the 'person' table with the value for 'fname' as ______.

Ali Signup and view all the answers

The `VALUES` clause in the `INSERT` command must match the order of the ______ specified.

columns Signup and view all the answers

The `ALTER TABLE` command is used to ______ a table.

rename Signup and view all the answers

Inserting a new row into the 'person' table also includes a value for 'salary' as ______.

450 Signup and view all the answers

To add a new column, use the `add column` ______ followed by the column name.

clause Signup and view all the answers

The `add column` clause requires the ______ type.

data Signup and view all the answers

You can also add ______ when modifying a table.

constraints Signup and view all the answers

The command `ALTER TABLE` allows you to ______ existing columns.

modify Signup and view all the answers

`char(10)` reserves 10 bytes of memory for a string, even if it contains fewer ______.

characters Signup and view all the answers

A `varchar(n)` data type is used for a ______ length string.

variable Signup and view all the answers

The `varchar(n)` data type only uses the actual space needed for the ______.

content Signup and view all the answers

`char` reserves a fixed amount of memory, while `varchar` uses ______ storage.

variable Signup and view all the answers

`varchar(n)` reserves space for a string of specified length but utilizes only the ______ needed.

actual space Signup and view all the answers

Study Notes

Database Design

Database design involves analysis, entity-relationship diagrams (ER diagrams), schema design (DDL), and data manipulation (DML).
Analysis is the initial step, defining entities (e.g., student, course) and their attributes (e.g., student ID, name, major).
Relationships between entities are specified (e.g., one-to-one, one-to-many, many-to-many relationships).
ER diagrams visually represent entities, attributes, and relationships.
Schema design (DDL) defines the structure of the database tables.
Data manipulation (DML) involves interacting with the data (e.g., inserting, updating, deleting).
Key attributes uniquely identify each entity. Examples include student ID, social security number, and serial numbers.

Attribute Types

Key Attribute: Uniquely identifies an entity, cannot duplicate (e.g., student ID).
Composite Attribute: Combination of single attributes (e.g., Address: city, street, etc.) to form complete information.
Multi-Value Attribute: Can have more than one value (e.g., phone numbers, email addresses).
Derived Attribute: Calculated from other attributes (e.g., age from birth date, GPA from grades).

Relationships

One-to-One (1:1): Each entity in one table corresponds to at most one entity in another table.
One-to-Many (1:M): One entity in one table can correspond to many entities in another table.
Many-to-Many (M:M): Many entities in one table can correspond to many entities in another table (often requiring an intermediary table).

Cardinality Ratio

Cardinality ratio describes the relationship between the entities: 1:1, 1:M, M:M.

Participation Constraint

Total Participation: Each entity in one table must be related to an entity in the other table.
Partial Participation: At least one entity in one table may not be related to an entity in the other table.

Types of Relationships

Binary Relationship: Two entities are involved in the relationship.
Recursive Relationship: A binary relationship where a relationship occurs within the same entity (e.g., employee is a supervisor of another employee).
Ternary Relationship: Three entities are involved.

Entity Types

Strong Entity: Exists independently and has its own key attribute.
Weak Entity: Dependent on a strong entity and does not have its own key attribute, needing a partial key from the strong entity to define it.

ER Diagram to Relational Schema Mapping

Entities in the ER diagram become tables in the relational schema.
Attributes become columns.
Relationships become relationships between tables using primary and foreign keys.

SQL

DDL (Data Definition Language) statements create, modify, and delete database objects (tables, columns, etc.).
- Create, alter, drop table
- Add, drop, alter columns
DML (Data Manipulation Language) statements manage data within database objects.
- Insert, update, delete rows
- Select, retrieve data
Constraints (e.g., NOT NULL, UNIQUE, PRIMARY KEY, FOREIGN KEY, CHECK) enforce data integrity and validity.
LIKE operator is used to filter data based on patterns (e.g., searching based on text patterns or names).
ORDER BY clause sorts the results of a query.
TOP clause limits the number of returned rows.
GROUP BY clause groups similar data to perform aggregate functions such as AVG, SUM, COUNT, and MAX.

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Description

This quiz explores the essential concepts of database design, including entity-relationship diagrams, schema design, and data manipulation techniques. Test your knowledge on key attributes, composite attributes, and the structural elements that define a well-designed database.

Database Design Fundamentals

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Podcast

Questions and Answers

This ensures that the column always has a ______,

Which can be useful for maintaining data ______ and enforcing business rules.

This process is important for ______ business rules.

A defined value in the column ensures ______ in the dataset.

Data ______ is essential for creating reliable reports.

To create a unique constraint, specify the column to be ______.

The unique constraint command uses the format UNIQUE (______).

An example of adding a unique constraint would be ALTER TABLE person ADD CONSTRAINT phone_unique UNIQUE(______).

The command adds a unique constraint named phone_unique to the ______ column.

In SQL, a unique constraint prevents duplicate values in a specified ______.

The ______ keyword defines a unique constraint.

Using unique constraints helps prevent ______ data and maintain data integrity.

It is important to carefully consider the unique ______ you create for a table.

Unique constraints help maintain data ______.

Creating unique constraints can prevent issues related to ______ data.

The INSERT command is used to add new rows to a ______.

The syntax for the INSERT command includes INSERT INTO ______ (column1, column2, ...).

In the example, the new row is inserted into the 'person' table with the value for 'fname' as ______.

The VALUES clause in the INSERT command must match the order of the ______ specified.

The ALTER TABLE command is used to ______ a table.

Inserting a new row into the 'person' table also includes a value for 'salary' as ______.

To add a new column, use the add column ______ followed by the column name.

The add column clause requires the ______ type.

You can also add ______ when modifying a table.

The command ALTER TABLE allows you to ______ existing columns.

char(10) reserves 10 bytes of memory for a string, even if it contains fewer ______.

A varchar(n) data type is used for a ______ length string.

The varchar(n) data type only uses the actual space needed for the ______.

char reserves a fixed amount of memory, while varchar uses ______ storage.

varchar(n) reserves space for a string of specified length but utilizes only the ______ needed.