QuerySphere

Front

What is a multi-valued attribute in an ER diagram?

Back

A multi-valued attribute is an attribute that can hold multiple values for a single entity. In an ER diagram, it is represented by a double oval.

Front

What SQL command is used to select all records from a table?

Back

SELECT * FROM table_name;

Front

How do you find events happening between two dates in SQL?

Back

Use the BETWEEN operator in a SQL query, e.g., SELECT * FROM Events WHERE event_date BETWEEN 'start_date' AND 'end_date';

Front

What SQL command retrieves unique values from a column?

Back

The DISTINCT keyword is used to retrieve unique values from a column.

Front

What is the purpose of the WHERE clause in SQL?

Back

The WHERE clause is used to filter records that meet a certain condition.

Front

What does the IN operator do in SQL?

Back

The IN operator allows you to specify multiple values in a WHERE clause.

Front

What is the difference between SQL and NoSQL databases?

Back

SQL databases are relational and use structured query language, while NoSQL databases are non-relational and can store unstructured data.

Front

What is an ER diagram?

Back

An Entity-Relationship (ER) diagram is a visual representation of the entities and their relationships in a database.

Front

What is a primary key in a database?

Back

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

Front

What is a foreign key in a database?

Back

A foreign key is a field in one table that uniquely identifies a row of another table, establishing a relationship between the two.