sql

Question 1

What is SQL and how is it different from languages like JavaScript?

Answer 1

it is a declaritive language. So instead of telling the language to “find” something. You can tell it what to find, and it will do it itself

Question 2

How do you retrieve specific columns from a database table?

Answer 2

you use:

select (name of column)

Question 3

How do you filter rows based on some specific criteria?

Answer 3

you can use the where clause.
you can get a subset of all rows in a table depending on the criteria

where “category” = ‘cleaning’

Question 4

What are the benefits of formatting your SQL?

Answer 4

The readability of your data

Question 5

What are four comparison operators that can be used in a where clause?

Answer 5

, =, !=

Question 6

How do you limit the number of rows returned in a result set?

Answer 6

using the limit command

Question 7

How do you retrieve all columns from a database table?

Answer 7

select *

Question 8

How do you control the sort order of a result set?

Answer 8

by using order by with the column selected.

it will be ascending by default, but can be descending if stated otherwise

Question 9

How do you add a row to a SQL table?

Answer 9

using the insert clause with the designating table

Question 10

What is a tuple?

Answer 10

a tuple is a group of values that is encased in a parenthsis

Question 11

How do you add multiple rows to a SQL table at once?

Answer 11

within the values clause. you would add X-amount of parenthesis seperated by commas. each new tuple will be a new row.

Question 12

How do you get back the row being inserted into a table without a separate select statement?

Answer 12

use the returning clause followed with a *. This will return the row that you have created. If you want specific values, you would replace the * with the list column items

Question 13

How do you update rows in a database table?

Answer 13

you use the update clause followed with the update and where

Question 14

Why is it important to include a where clause in your update statements?

Answer 14

IT IS IMPORTANT TO USE the WHERE clause to make sure that you are not updating EVERYTHING

Question 15

How do you delete rows from a database table?

Answer 15

use the delete from clause folowered by a where clause

Question 16

How do you accidentally delete all rows from a table?

Answer 16

where you forget to use a where clause with the delete

Question 17

What is a foreign key?

Answer 17

it is a value/column that specifically refers to values in another table.

Question 18

How do you join two SQL tables?

Answer 18

we use the `join` clause
Designating the table and how they are connect.
`select *
from "products
join "suppliers" using ("supplierId")`

Question 19

How do you temporarily rename columns or tables in a SQL statement?

Answer 19

you use the as clause:

select “products”.”name as “product…

this will change the column “name” in the table “products” to the name “product”