SQL | MCQs

Explanation

Explanation

In the relational model of databases, a primary key is a specific choice of a minimal set of attributes that uniquely specify a tuple in a relation.

Informally, a primary key is "which attributes identify a record", and in simple cases are simply a single attribute: a unique id.

A field is also known as a column

that stores the same type of data and hence can be called a category of data.

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vu FIA CBT PAPER 15-12-2021

Explanation

The single equals sign = is used for comparison in SQL conditions.

The query correctly filters rows where the Job column matches the string 'Clerk'.

Explanation

The SELECT * syntax retrieves all columns from the specified table.

It is the standard SQL command for displaying complete table data.

Explanation

SQL is the specific language used to create tables, store, retrieve, and update data in a relational database.

It is designed for managing and manipulating structured data in relational databases.

Explanation

The Cascade Delete option is a database feature that automatically deletes all related records in a child table when a record is deleted from a parent table.

This helps maintain data consistency and integrity by ensuring that all related data is removed when a primary record is deleted.

Explanation

In SQL, to retrieve data stored in our tables, we use the SELECT statement.

Explanation

Left Join: Returns all rows from the left table and the matched rows from the right table.

If there is no match, the result is NULL on the side of the right table.

In SQL, the syntax for a left join would look like this:

Explanation

• Communication with MySQL is established through network calls.
• MySQL is a client-server system, where clients communicate with the server over a network connection.
• This communication involves sending queries, commands, and receiving responses over the network.

Explanation

• This is the standard SQL syntax to drop a column from a table.
• The ALTER TABLE statement is used to modify the structure of a table, and the DROP COLUMN clause is used to delete a column.
• An example: ALTER TABLE MyTable DROP COLUMN MyColumn;