Learn SQL Basics

What does SQL stand for?

• Structured Query List

• Standard Query Language

• Simple Query Language

• Structured Query Language

Answer explanation

SQL stands for Structured Query Language, which is the standard language used for managing and manipulating databases. The other options do not accurately represent the full name of SQL.

Which command is used to select data in SQL?

• GET

• FETCH

• SELECT

• RETRIEVE

Answer explanation

The correct command to select data in SQL is 'SELECT'. It is specifically designed for querying and retrieving data from databases, while the other options do not serve this purpose.

What symbol is used to select all columns in a table?

• @

• $

• *

• #

Answer explanation

The symbol '*' is used in SQL to select all columns from a table. It acts as a wildcard, indicating that every column should be included in the result set.

What is the basic structure of a SELECT statement?

• SELECT column1, column2 FROM table_name;

• SELECT column1, column2;

• SELECT * WHERE table_name;

• FROM table_name SELECT column1, column2;

Answer explanation

The correct structure of a SELECT statement is 'SELECT column1, column2 FROM table_name;'. This specifies which columns to retrieve from a specific table, making it the complete and valid syntax.

Can you name a SQL command that adds new data?

• SELECT * FROM

• DELETE FROM

• INSERT INTO

• UPDATE

Answer explanation

The SQL command 'INSERT INTO' is used to add new data to a table. In contrast, 'SELECT * FROM' retrieves data, 'DELETE FROM' removes data, and 'UPDATE' modifies existing data.

What keyword is used to filter results in a SELECT statement?

• FILTER

• SELECT

• ORDER BY

• WHERE

Answer explanation

The WHERE keyword is used in a SELECT statement to filter records based on specified conditions. It allows you to retrieve only the rows that meet certain criteria, making it essential for filtering results.

What does the WHERE clause do in SQL?

• Filters records based on specified conditions.

• Sorts records in ascending order.

• Joins multiple tables together.

• Aggregates data into summary statistics.

Answer explanation

The WHERE clause in SQL is used to filter records based on specified conditions, allowing users to retrieve only the data that meets certain criteria.

Is it possible to sort results in a SELECT statement?

• No, sorting is not allowed in a SELECT statement.

• You can only sort results in a DELETE statement.

• Yes, it is possible to sort results in a SELECT statement.

• Sorting can only be done in UPDATE statements.

Answer explanation

Yes, sorting is possible in a SELECT statement using the ORDER BY clause. This allows you to arrange the results based on one or more columns, making it a fundamental feature of SQL for retrieving organized data.

What is the purpose of the FROM clause in SQL?

• To determine the order of the results returned by the query.

• To specify the source table(s) for a SQL query.

• To define the conditions for filtering records.

• To specify the columns to be returned in the result set.

Answer explanation

The FROM clause in SQL is essential as it specifies the source table(s) from which to retrieve data. This is crucial for the query to know where to look for the records, making it the correct choice.

Can you use SELECT to get data from multiple tables?

• Yes, you can use SELECT to get data from multiple tables.

• SELECT cannot be used to join tables.

• You can only use SELECT with views, not tables.

• No, SELECT can only retrieve data from one table.

Answer explanation

Yes, you can use SELECT to retrieve data from multiple tables by using JOIN operations. This allows you to combine rows from two or more tables based on a related column, making it a powerful feature of SQL.