SQL

• What does SQL stand for?

  Structured Query Language
• What is the purpose of SQL?

  To search database tables for specific data
• What do records and fields refer to in a database table?

  Rows and columns
• Which keywords are the most important in SQL?

  SELECT and FROM
• How do you write a query to retrieve data?

  Use SELECT followed by field names and FROM
• What does the SELECT keyword do?

  Retrieves specified fields from a database
• What does the FROM keyword specify?

  The table from which to retrieve data
• What does the wildcard character '*' do in SQL?

  Returns all fields from a table
• What is the purpose of the WHERE keyword?

  To specify conditions for returned records
• How would you filter hotels with a rating greater than 4.1?

  SELECT * FROM hotels WHERE hotelRating > 4.1
• What do Boolean operators AND and OR do in SQL?

  Make searches more specific
• Write a SQL query to find hotels with an en-suite bathroom and price under £45.

  SELECT hotelName FROM hotels WHERE bathroom = "En-suite" AND priceInPounds < 45
• What does the ORDER BY keyword do in SQL?

  Sorts records in ascending or descending order
• How would you write a query to find hotels with more than 100 rooms, excluding Windy Hotel?

  SELECT hotelName, priceInPounds FROM hotels WHERE rooms > 100 AND hotelName != "Windy Hotel"
• What is the result of the query SELECT hotelName FROM hotels WHERE rooms > 100 AND hotelName != "Windy Hotel"?

  Returns names of hotels with >100 rooms
• What is the structure of the viewings table?

  customer, propertyNumber, time
• How do you join two tables in SQL?

  Using the WHERE clause to match fields
• Write a SQL query to find addresses and times of viewings with "Helen".

  SELECT properties.address, viewings.time FROM properties, viewings WHERE viewings.propertyNumber = properties.propertyNumber AND customer = "Helen" ORDER BY time ASC
• What is the result of the query SELECT properties.address, viewings.time FROM properties, viewings WHERE customer = "Helen" ORDER BY time ASC?

  Returns addresses and times for Helen's viewings
• What is the structure of the properties table?

  propertyNumber, parking, address
• What does the INSERT INTO statement do?

  Adds new records to a table
• What are the key components of a SQL query?

  • SELECT: specifies fields to retrieve
  • FROM: specifies the table to search
  • WHERE: filters records based on conditions
  • ORDER BY: sorts records in a specified order
• How do you filter records in SQL using multiple conditions?

  • Use WHERE to specify conditions
  • Combine conditions with AND or OR
  • Example: WHERE condition1 AND condition2
• What are the differences between the viewings and properties tables?

  • Viewings: contains customer, propertyNumber, time
  • Properties: contains propertyNumber, parking, address
  • Viewings link to Properties via propertyNumber
• always write

  SELECT

  FROM

  WHERE