Flashcards in SQL Deck (27)
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1
What is PostgreSQL and what are some alternative relational databases?
a free open source Relational Database Management System, MySQL, SQL Server (Microsoft), Oracle (Oracle Corporation)
2
What are some advantages of learning a relational database?
they are the most widely used kind of database
3
What is one way to see if PostgreSQL is running?
sudo service postgresql status or top
4
What is a database schema?
a description of how data should be structured
5
What is a table?
a list of rows having the same set of attributes
6
What is a row?
all of the data for an individual entry
7
What is SQL and how is it different from languages like JavaScript?
Structured Query Language, the primary way of interacting with relational databases, declarative programming language (like HTML and CSS)
8
How do you retrieve specific columns from a database table?
select "column", from "table"
9
How do you filter rows based on some specific criteria?
where "column" = 'value'
10
What are the benefits of formatting your SQL?
readability, style consistency
11
What are four comparison operators that can be used in a where clause?
=, , !=
12
How do you limit the number of rows returned in a result set?
limit #
13
How do you retrieve all columns from a database table?
select *
14
How do you control the sort order of a result set?
order by "column" (desc)
15
How do you add a row to a SQL table?
insert into "table" ("column")
values ('value')
16
What is a tuple?
a list of values
17
How do you add multiple rows to a SQL table at once?
specify more than one tuple of values, separated by commas
18
How do you get back the row being inserted into a table without a separate select statement?
returning clause
19
How do you update rows in a database table?
update "table"
set "column" = 'value'
where "column" = 'value'
20
Why is it important to include a where clause in your update statements?
if where clause isn't used, all rows would be updated
21
How do you delete rows from a database table?
delete from "table"
where "column" = 'value'
22
How do you accidentally delete all rows from a table?
by not including a where clause
23
What is a foreign key?
a column that links tables together
24
How do you join two SQL tables?
join "table" using ("column")
25
How do you temporarily rename columns or tables in a SQL statement?
create an alias by using as keyword
select "column" as "alias"
26
What are some examples of aggregate functions?
max( ), count( ), min( ), sum( )
27
