SQL Flashcards
What is SQL and how is it different from languages like JavaScript?
SQL is way of interacting with relational databases and is different from JavaScript because it is a declarative programming languages. You also don’t really tell the computers what to do.
How do you retrieve specific columns from a database table?
using select “column name or attributes”
How do you filter rows based on some specific criteria?
you use where clause “column name” = the ‘row name’
What are the benefits of formatting your SQL?
It makes your code easier to read and decipher
What are four comparison operators that can be used in a where clause?
=, , !=
How do you limit the number of rows returned in a result set?
with limit operator
How do you control the sort order of a result set?
order by “column name” - by default it is ascending order and can make it descending by desc operator
How do you retrieve all columns from a database table?
select *
How do you add a row to a SQL table?
using insert keyword with what columns and values you want to insert
What is a tuple?
list of values
How do you add multiple rows to a SQL table at once?
you specify more than one tuple of values, separated by commas
How do you get back the row being inserted into a table without a separate select statement?
using returning *
How do you update rows in a database table?
use update statement with “file name” and set clause
Why is it important to include a where clause in your update statement?
Without the where clause, set value will be updated to all rows
How do you delete rows from a database table?
Use delete statement with where clause
How do you accidentally delete all rows from a table?
delete from “file name”
What is a foreign key?
foreign key links one table to another with same attributes
How do you join two SQL tables?
using join clause with using keyword and attribute you want to join together
How do you temporarily rename columns or tables in a SQL statement?
using as keyword
What are some examples of aggregate functions?
sum(), min(), every(), avg()
What is the purpose of a group by clause?
To separate rows into groups and perform aggregate functions on those groups of rows
