Week 4 - Ins and Outs of Core Data Tools

Question 1

SQL (Structured Query Language)

Answer 1

It can help you investigate huge databases, track down text (referred to as strings) and numbers, and filter for the exact kind of data you need—much faster than a spreadsheet can.

Question 2

Query

Answer 2

a request for data or information from a database. When you query databases, you use SQL to communicate your question or request

Question 3

Syntax

Answer 3

• unique set of guidelines followed by SQL.
• is the predetermined structure of a language that includes all required words, symbols, and punctuation, as well as their proper placement.
• e.g.
  SELECT - choose the column you want to return
  FROM - choose the tables where the columns you want are located
  WHERE - to filter for certain information.

Question 4

WHERE

Answer 4

WHERE field1 = ‘Chavez’

However, if you are looking for all customers with a last name that begins with the letters “Ch,” the WHERE clause would be:

WHERE field1 LIKE ‘Ch%’

You can conclude that the LIKE clause is very powerful because it allows you to tell the database to look for a certain pattern! The percent sign (%) is used as a wildcard to match one or more characters. In the example above, both Chavez and Chen would be returned. Note that in some databases an asterisk (*) is used as the wildcard instead of a percent sign (%).

Question 5

ALIASES

Answer 5

• can also make it easier on yourself by assigning a new name or alias to the column or table names to make them easier to work with (and avoid the need for comments).
• This is done with a SQL AS clause. In the example below, the alias last_name has been assigned to field1 and the alias customers assigned to table.
• These aliases are good for the duration of the query only. An alias doesn’t change the actual name of a column or table in the database.