Podcast
Questions and Answers
Which command in DML allows you to remove unnecessary data from a database?
Which command in DML allows you to remove unnecessary data from a database?
- Insert
- Delete (correct)
- Update
- Select
What does the Order By clause do in a SELECT Statement?
What does the Order By clause do in a SELECT Statement?
- Filters data based on a condition
- Removes redundant data from the output
- Groups data into well-structured relations
- Sorts the result set in a specified order (correct)
What is the primary goal of normalization in a database?
What is the primary goal of normalization in a database?
- To enhance the performance of hardware
- To simplify the database queries
- To increase redundancy of data
- To minimize data duplication and organize data (correct)
Which of the following is NOT a benefit of normalization?
Which of the following is NOT a benefit of normalization?
What is indicated by the term 'cardinality' in the context of database relationships?
What is indicated by the term 'cardinality' in the context of database relationships?
Which normal form removes multivalued dependencies?
Which normal form removes multivalued dependencies?
In an entity relationship diagram, how are entities represented?
In an entity relationship diagram, how are entities represented?
Which statement about a one-to-many relationship is true?
Which statement about a one-to-many relationship is true?
Flashcards
DML (Data Manipulation Language)
DML (Data Manipulation Language)
A language for interacting with databases, allowing you to view, filter, insert, delete, and update data.
Insert
Insert
A command that adds one or more records to a database table.
Delete
Delete
A command that removes unnecessary data from a database table.
Select
Select
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Normalization
Normalization
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Normal Forms
Normal Forms
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Relationships
Relationships
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Entity Relationship Diagram (ERD)
Entity Relationship Diagram (ERD)
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Study Notes
Lesson 5: DML (Data Manipulation Language)
- Data Manipulation Language (DML) commands allow viewing, filtering, inserting, deleting, and updating database data.
- INSERT adds new data to tables.
- UPDATE modifies existing data.
- DELETE removes data.
- SELECT (or Select Statements) retrieves data from tables.
- SQL Query Designer is used to code DML commands.
- UPPER converts data to uppercase.
- Concatenation joins column names.
- Single quotes enclose string values.
- SPACE function adds spaces.
Lesson 5: Statements
- ORDER BY clause sorts results (ascending or descending).
- WHERE clause filters data, selecting only records that meet specific conditions.
Lesson 6: Normalization
- Normalization organizes data, reducing redundancy in relational database design, grouping attributes into well-structured relations.
- Benefits of normalization:
- Improved database organization.
- Reduced data redundancy.
- Enhanced data consistency.
- Increased design flexibility.
- Improved security.
- Normal Forms:
- Non-First Normal Form (NonNF).
- First Normal Form (1NF).
- Second Normal Form (2NF).
- Third Normal Form (3NF).
- Boyce-Codd Normal Form (BCNF).
- Fourth Normal Form (4NF).
Lesson 7: Relationships
- Relationships exist between database tables when one table's foreign key refers to another table's primary key.
- Cardinality: number of instances of an entity in a relation.
- One-to-One: One row links to only one row in another table (rare).
- One-to-Many: One row can link to many rows in another table.
- Many-to-Many: One row in a table can link to many rows in another table.
- Entity-Relationship Diagrams (ER diagrams) represent a database's conceptual design illustrating table relationships.
Lesson 7: ER Diagram Notation
- Entities: Real-world objects (represented by triangles).
- Attributes: Properties of entities (represented by ellipses).
- Relationships: Associations between entities (represented by diamond-shaped boxes).
Lesson 9: Backup and Recovery
- Backup: Duplicated copy of data.
- Restoration: Retrieving data from a backup.
- Backup and recovery strategies prevent data loss.
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