SQL Basic Review

What type of database model organizes data in tables with rows and columns?

• Hierarchical

• Relational

• Network

• Object Oriented

Answer explanation

Relational databases organize data in tables with rows and columns.

In a database, what is a unique identifier for each record in a table called?

• Primary key

• Foreign key

• Secondary key

• Index key

Answer explanation

A primary key is a unique identifier for each record in a table.

Which SQL statement is used to retrieve data from a database?

• SELECT

• UPDATE

• DELETE

• INSERT

Answer explanation

The SELECT statement is used to retrieve data from a database.

What is the purpose of normalization in a database?

• Increase data redundancy

• Reduce data redundancy

• Improve data security

• Optimize query speed

Answer explanation

Normalization aims to reduce data redundancy and improve data integrity.

Which of the following is not a characteristic of a good database design?

• Data redundancy

• Scalability

• Data integrity

• Efficiency

Answer explanation

A good database design should minimize data redundancy.

Which data type is used in SQL to store true or false values?

• Boolean

• Varchar

• Int

• Float

Answer explanation

BOOLEAN data type is used to store true or false values.

In SQL, which data type is best suited for storing large texts such as articles or comments?

• Text

• Blob

• Varchar

• Char

Answer explanation

TEXT data type is ideal for storing large texts.

Which SQL data type is used to store numerical values with fixed precision and scale?

• Integer

• Decimal

• Date

• Varchar

Answer explanation

DECIMAL data type is used for numerical values with fixed precision and scale.

In SQL, what is the difference between CHAR and VARCHAR data types?

• CHAR is variable length, VARCHAR is fixed length

• CHAR is fixed length, VARCHAR is variable length

• No difference

• VARCHAR is used only for numeric data

Answer explanation

CHAR is used for fixed-length strings, while VARCHAR is used for variable-length strings.

What data type would you use in SQL to store a date and time value together?

• DATETIME

• DATE

• TIME

• TIMESTAMP

Answer explanation

DATETIME data type is used to store both date and time values together.