Beginner SQL Commands

Question 1

SELECT

Answer 1

is the clause we use every time we want to query information from a DB.

Question 2

AS

Answer 2

renames a column or table

Question 3

DISTINCT

Answer 3

return unique values

Question 4

WHERE

Answer 4

is a popular command that lets you filter the results of the query based on conditions that you specify

Question 5

LIKE AND BETWEEN

Answer 5

Special operators

Question 6

AND & OR

Answer 6

combines multiple conditions

Question 7

ORDER BY

Answer 7

Sorts the results

Question 8

LIMIT

Answer 8

Specifies the maximum number of rows that query will return

Question 9

CASE

Answer 9

creates different outputs

Question 10

What are aggregates?

Answer 10

Calculations performed on multiple rows of a table.

Question 11

COUNT()

Answer 11

Returns the total count of whatever the argument was in

Question 12

SUM()

Answer 12

Returns the sum of whatever argument was added

Question 13

MAX()/MIN()

Answer 13

Returns the maximum or minimum value in the column that you specified

Question 14

AVG()

Answer 14

Returns the avg of the column

Question 15

ROUND()

Answer 15

ROUND(Column Name, number of decimal places)

Question 16

HAVING

Answer 16

Used when we want to limit the results of a query based on an aggregate property (Group)
Always comes after GROUP BY but before ORDER BY and LIMIT statements

Question 17

What does the .forEach() array method do?

Answer 17

Executes a callback function on each of the elements in an array in order.

Question 18

What does the.map() array method do?

Answer 18

Executes a callback function on each element in an array. It returns a new array made up of the return values from the callback function REVIEW

Question 19

What does the .filter() array method do?

Answer 19

Executes a callback function on each element in an array. THe callback function for eac of the elements must return either TRUE or FALSE. The returned array is a new array with any elements for which the callback funciton returns TRUE.

Question 20

What does the .findindex() method do?

Answer 20

Returns the index of the first element that evaluates to TRUE in the callback function

Question 21

What does the .reduce() method do?

Answer 21

Returns a single value after iterating through the elements of an array. Thereby reducing the array.
Study iterators/the types of iterators that there are.

Question 22

What are the two ways to access an object’s properties?

Answer 22

dot notation and bracket notation

Question 23

When do you have to use bracket notation to access object properties?

Answer 23

When accessing keys that have numbers, spaces, or special characters in them.

Question 24

What does it mean when you say objects are mutable?

Answer 24

It means that objects can be updated after they are created.

Question 25

What are the two things that can happen with property assignment?

Answer 25

1. If a property already existed then that value will be replaced with the new value
2. If there was no property with that name, a new property will be added.