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Questions and Answers
Which of the following is a Data Manipulation Language (DML) statement?
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 add new records to a table?
Which DML statement is used to modify existing records in 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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
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?
What should be avoided in predicates for query optimization?
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When using LIKE operator in a predicate, what should be avoided?
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?
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?
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?
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?
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.