Module 3: SQL Queries

Question 1

SQL

Answer 1

Structured Query Language

Large data sets.

Tool that makes working with large datasets easier.

Question 2

Relational Database

Answer 2

A database that contains a series of tables that can be connected to form relationships

Question 3

Features of SQL

Answer 3

Larger Datasets -
Access tables across a database - can pull information from different sources in the database.

Prepare data for further analysis in another software

Fast and powerful functionality
Great for collaborative work and tracking queries run by all users.

A language used to interact with different databases

Stored across a database

Question 4

Features of spreadsheets

Answer 4

Smaller data sets - Data that you input.
Enter data manually
Create graphs and visualisations in the same program
Built-in spell check and other useful functions
best when working solo on a project

Generate with a program

Stored locally

Build in functionalities

Question 5

Commonality between spreedsheets and SQL

Answer 5

Use formulars, use arthimatite. and join data.

Question 6

INSERT INTO

Answer 6

Allows you to insert a new data entry

Question 7

UPDATE and SET

Answer 7

Allows you to update a address

Question 8

DISTINCT in SELECT

Answer 8

Can allow you to remove duplicates

Question 9

What is one thing you should remember from the FROM statement

Answer 9

Located in a data so in the FROM section of an SQL query, you have to remember that the data is protected by the personal project name therefore the template of the file path structuring the structure:

personalprojectname.customer_data.customer_address

Question 10

Text Strings

Answer 10

A group of characters within a cell, commonly composed of letter, numbers, or both

Question 12

How can using Length filter and clean data

Answer 12

You can use length to identify how many text string characters are within a table.

Such as, if the country name is meant 2 characters long you can use length to identify if there are any places where the text string is longer than meant to be for example

WHERE
LENGTH(state) > 2

And any rows with more than two characters will be identified.

OH for example if is a result of the above query then it is known that there is an additional space within the role highlighting in error.

Question 13

How can TRIM be used to filter and clean data

Answer 13

If the text combo TRIM can be used to only pull the data that is relevant to the command that you provide it.

For example if you use TRIM to eliminate any spaces within both sets of data you can do so by only adding in the text string that you want to receive back, the query will then eliminate any additional characters or strings that you have not provided while still bringing back the relevant information.

Question 14

CAST()

Answer 14

Can be used to convert anything from one data type to another

Question 15

Typecasting

Answer 15

Converting data from one type to another

Question 16

Float

Answer 16

Number that contains a decimal

Question 17

Why would you use FLOAT instead of UPDATE?

Answer 17

It would be preferable to use the Cast function instead the update function if the data type of the column has been mislabelled.

Question 18

CONCAT()

Answer 18

Adds strings together to create new text strings that can be used as unqiue keys

Question 18

How do queries within SQL make it particularly useful in relation to original datasets

Answer 18

SQL in a nondestructive way will manipulate and transform data without damaging or changing the original data set. However is still always important to ensure that you retain the original data set document in its original form or backups as errors often happen when manipulating original data, the sources say viewers a data analyst a lot of more work.

Question 19

COALESCE()

Answer 19

Can be used to return non-null values in a list