Go on. Explore!

lvl 0 • 0 xp

lvl 1

Home Market Decks Interests

SQL

memorize.ai (lvl 286)

Section 1

Preview this deck

Aggregate Functions

Front

1 / 25

SQL

0.0

0 reviews

5			0
4			0
3			0
2			0
1			0

Active users

All-time users

Favorites

Last updated

1 year ago

Date created

Mar 14, 2020

Cards (25)

Section 1

(25 cards)

Aggregate Functions

Front

Used with SELECT to return mathematical summaries on columns (calculate value using records) AVG(x), MAX(x), MIN(x), SUM(x), COUNT(x)

Back

DELETE

Front

removes data from a table but does not delete the table

Back

DQL

Front

Data Query Language - for reading information, searching a database SELECT

Back

RDBMS

Front

Relational Database Management System software designed to manage a database

Back

Tables

Front

composed of columns (fields) which holds attributes and rows (records) which model an instance

Back

WHERE clause

Front

The WHERE clause is used to extract records that fulfill a specified criteria. (cannot be used with aggregates) Syntax: SELECT column_name,column_name FROM table_name WHERE column_name operator value;

Back

HAVING clause

Front

HAVING is an extra clause we use with GROUP BY because oracle wont let you use WHERE. WHERE filters out records to return, but GROUP BY doesn't return records used to add condition to your GROUP BY

Back

SQL

Front

Structured Query Language Used for managing data held inside an RDBMS Freedom to choose how much code is executed at a time

Back

TRUNCATE

Front

DDL operation used to delete data from a table but preserve its structure for future use very fast and ideal for deleting data from a temp table

Back

GROUP BY clause

Front

The clause that groups rows based on the specified column used with aggregate functions to break records into groups Syntax: SELECT x, COUNT(x) FROM table_name GROUP BY x;

Back

DML

Front

Data Manipulation Language - adds, removes, or edits data in a data base INSERT, UPDATE, DELETE

Back

Aliases

Front

the temporary names given to a table or column for the purpose of a particular SQL query created to make a table names more readable

Back

Subqueries

Front

a query within a query The outer query is called as main query and inner query is called as subquery. the subquery will generally execute first and its output will be used to complete the query condition of the main query (GROUP BY = ORDER BY for Subquery)

Back

DCL

Front

Data Control Language - for granting permission to users GRANT, REVOKE

Back

5 SQL sublanguages

Front

DDL - Data definition language DML - Data manipulation language DQL - Data query language DCL - Data control language TCL - Transaction control language

Back

VARCHAR2(x)

Front

This datatype is used to store variable length character strings. The number you specify is just the maximum number of bytes that can be stored (although 1 byte is minimum). You should use this datatype when you don't know the exact length of stored strings.

Back

Schema

Front

group of database objects associated with a database (a database of tables)

Back

TCL

Front

Transaction Control Language - for generating transactions COMMIT, ROLLBACK, SAVEPOINT

Back

COMMIT

Front

Cannot rollback changes once you commit Automatically updates in AWS database after commit

Back

How to you create/delete a table in SQL?

Front

Create Table name Drop Table name

Back

Cursor

Front

result set of a SQL query - what we get back from a database search - anything from the select

Back

Database

Front

a collection of objects designed to hold information

Back

View

Front

virtual tables based on the result of a query

Back

Relational Database

Front

a database which holds information in tables related to each other

Back

DDL

Front

Data Definition Language - defines the rules and structures of a database CREATE, ALTER, DROP, RENAME, TRUNCATE

Back