Podcast
Questions and Answers
Which of the following is a Data Manipulation Language (DML) statement?
Which DML statement is used to add new records to a table?
Which DML statement is used to modify existing records in a table?
Which DML statement is used to remove records from a table?
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Which DML statement is used to retrieve data from a table?
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Which of the following is not a characteristic of DML statements?
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Which DML statement is used to undo changes made to a database?
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Which DML statement is used to make changes to a database permanent?
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Which DML statement is used to start a transaction?
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Which DML statement is used to control the level of access that users have on database objects?
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What operation in Database Management System is used to delete a tuple from a relation?
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In a relational model, what is the term used to refer to the degree of a relation?
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Which type of operation in Database Management System creates a new relation with fewer attributes than the original relation?
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What is the purpose of the join operation in a Database Management System?
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Which Database Model organizes data in an upside-down tree structure?
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What type of language is SQL (Structure Query Language) considered to be?
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What should be avoided in predicates for query optimization?
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When using LIKE operator in a predicate, what should be avoided?
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Which type of join is advised over the other for better performance?
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In SQL, when should the ORDER BY clause be used?
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What is a common guideline for indexing columns in SQL for optimization?
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What is a common recommendation to minimize the number of columns in a table for optimization?
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Study Notes
Data Manipulation Language (DML) Statements
- DML statements are used to interact with database records.
- Common DML statements include
INSERT
,UPDATE
,DELETE
, andSELECT
.
Adding New Records
- The
INSERT
statement is utilized to add new records to a table.
Modifying Existing Records
- The
UPDATE
statement is used to modify existing records within a table.
Removing Records
- The
DELETE
statement is employed to remove records from a table.
Retrieving Data
- The
SELECT
statement retrieves data from a table.
Characteristics of DML Statements
- DML statements modify the data in a database but do not define the schema or structure itself.
Undo Changes
- The
ROLLBACK
statement is used to undo changes made to a database.
Commit Changes
- The
COMMIT
statement makes changes to a database permanent.
Starting a Transaction
- The
BEGIN TRANSACTION
statement initiates a database transaction.
Controlling Access
- The
GRANT
statement controls the level of access users have on database objects.
Deleting Tuples
- The
DELETE
operation in Database Management Systems removes a tuple from a relation.
Degree of a Relation
- In relational models, the degree of a relation refers to the number of attributes (columns) in that relation.
Creating New Relations
- The projection operation generates a new relation with fewer attributes than the original relation.
Join Operation Purpose
- The join operation combines data from two or more relations based on a related attribute.
Data Organization Model
- The hierarchical database model organizes data in an upside-down tree structure.
SQL Language Classification
- SQL (Structured Query Language) is classified as a procedural language.
Query Optimization - Predicates
- Avoid complex predicates that can slow down query optimization efforts.
LIKE Operator Optimization
- When using the LIKE operator, avoid leading wildcards, as they significantly degrade performance.
Join Types for Performance
- Inner joins are generally advised over outer joins for better performance.
ORDER BY Clause Usage
- Use the
ORDER BY
clause in SQL when specific ordering of the result set is required.
Indexing Guidelines
- A common guideline for indexing in SQL is to index columns frequently used in WHERE clauses for optimization.
Table Column Minimization
- To optimize performance, minimize the number of columns in a table, focusing on essential data only.
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Description
Test your knowledge on the components of a Database Management System (DBMS), such as hardware, software, data, and users. Learn about how DBMS is used to input, sort, organize, and store data effectively.