Mysql Query Cheat Sheet

| 02-05-2021
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Download this 2-page SQL Basics Cheat Sheet in PDF or PNG format, print it out, and stick to your desk.

The SQL Basics Cheat Sheet provides you with the syntax of all basics clauses, shows you how to write different conditions, and has examples. You can download this cheat sheet as follows:

WebsiteSetup.org- MySQL Cheat Sheet Using SQL, you are able to interact with the database by writing queries, which when executed, return any results which meet its criteria. Here’s an example query:- Using this SELECT statement, the query selects all data from all columns in the user’s table. Our SQL Cheat Sheet enables you to revise almost the entire set of SQL Commands quickly. It is highly recommended to go through this cheat sheet if you are: Preparing for your SQL exam Going for an interview.

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SQL Basics Cheat Sheet

SQL

SQL, or Structured Query Language, is a language to talk to databases. It allows you to select specific data and to build complex reports. Today, SQL is a universal language of data. It is used in practically all technologies that process data.

SAMPLE DATA

QUERYING SINGLE TABLE

Fetch all columns from the country table:

Fetch id and name columns from the city table:

Fetch city names sorted by the rating column in the default ASCending order:

Fetch city names sorted by the rating column in the DESCending order:

Aliases

Columns

Tables

FILTERING THE OUTPUT

COMPARISON OPERATORS

QueryFetch names of cities that have a rating above 3:Fetch names of cities that are neither Berlin nor Madrid:

TEXT OPERATORS

Fetch names of cities that start with a 'P' or end with an 's':Fetch names of cities that start with any letter followed by'ublin' (like Dublin in Ireland or Lublin in Poland):

OTHER OPERATORS

Fetch names of cities that have a population between 500K and 5M:Fetch names of cities that don't miss a rating value:Fetch names of cities that are in countries with IDs 1, 4, 7, or 8:

QUERYING MULTIPLE TABLES

INNER JOIN

JOIN (or explicitly INNER JOIN) returns rows that have matching values in both tables.

LEFT JOIN

LEFT JOIN returns all rows from the left table with corresponding rows from the right table. If there's no matching row, NULLs are returned as values from the second table.

RIGHT JOIN

RIGHT JOIN returns all rows from the right table with corresponding rows from the left table. If there's no matching row, NULLs are returned as values from the left table.

FULL JOIN

FULL JOIN (or explicitly FULL OUTER JOIN) returns all rows from both tables – if there's no matching row in the second table, NULLs are returned.

CROSS JOIN

CROSS JOIN returns all possible combinations of rows from both tables. There are two syntaxes available.

NATURAL JOIN

NATURAL JOIN will join tables by all columns with the same name.

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Mysql Query Cheat Sheet Excel

NATURAL JOIN used these columns to match rows:
city.id, city.name, country.id, country.name.
NATURAL JOIN is very rarely used in practice.

AGGREGATION AND GROUPING

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GROUP BYgroups together rows that have the same values in specified columns. It computes summaries (aggregates) for each unique combination of values.

AGGREGATE FUNCTIONS

  • avg(expr) − average value for rows within the group
  • count(expr) − count of values for rows within the group
  • max(expr) − maximum value within the group
  • min(expr) − minimum value within the group
  • sum(expr) − sum of values within the group

EXAMPLE QUERIES

Find out the number of cities:

Find out the number of cities with non-null ratings:

Find out the number of distinctive country values:

Find out the smallest and the greatest country populations:

Find out the total population of cities in respective countries:

Find out the average rating for cities in respective countries if the average is above 3.0:

SUBQUERIES

A subquery is a query that is nested inside another query, or inside another subquery. There are different types of subqueries.

SINGLE VALUE

The simplest subquery returns exactly one column and exactly one row. It can be used with comparison operators =, <, <=, >, or >=.

This query finds cities with the same rating as Paris:

Mysql

MULTIPLE VALUES

A subquery can also return multiple columns or multiple rows. Such subqueries can be used with operators IN, EXISTS, ALL, or ANY.

This query finds cities in countries that have a population above 20M:

CORRELATED

A correlated subquery refers to the tables introduced in the outer query. A correlated subquery depends on the outer query. It cannot be run independently from the outer query.

This query finds cities with a population greater than the average population in the country:

This query finds countries that have at least one city:

SET OPERATIONS

Set operations are used to combine the results of two or more queries into a single result. The combined queries must return the same number of columns and compatible data types. The names of the corresponding columns can be different

UNION

UNION combines the results of two result sets and removes duplicates. UNION ALL doesn't remove duplicate rows.

This query displays German cyclists together with German skaters:

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INTERSECT

INTERSECT returns only rows that appear in both result sets.

This query displays German cyclists who are also German skaters at the same time:

EXCEPT

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EXCEPT returns only the rows that appear in the first result set but do not appear in the second result set.

Mysql Query Tutorial

This query displays German cyclists unless they are also German skaters at the same time:

Try out the interactive SQL Basics course at LearnSQL.com, and check out our other SQL courses.

Mysql Query Commands Cheat Sheet

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