Basic SQL Tutorial

Basic SQL

โดย Yuttana J.

: mySQL for Beginner

School of Informaticstinybronko@gmail.com

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Today’s Agenda

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Querying data from MySQL database1

Modifying data in MySQL2

Working with MySQL databases3

MySQL Globalization4

Download MySQL Sample Database

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Create new account

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SQL statement

CREATE USER 'user1'@'%' IDENTIFIED WITH mysql_native_password AS '***';

GRANT ALL PRIVILEGES ON *.* TO 'user1'@'%' REQUIRE NONE WITH GRANT OPTION;

CREATE DATABASE IF NOT EXISTS `user1`; GRANT ALL PRIVILEGES ON `user1`.* TO 'user1'@'%'; GRANT ALL PRIVILEGES ON `user1\_%`.* TO 'user1'@'%';

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SQL statement (REVOKE)

REVOKE ALL PRIVILEGES ON *.* FROM'user1'@'%'; GRANT SELECT ON *.* TO'user1'@'%' ;

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REVOKE ALL PRIVILEGES ON `user1`.* FROM 'user1'@'%'; GRANT ALL PRIVILEGESON `user1`.* TO 'user1'@'%' WITH GRANT OPTION;

SELECT Statement

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the syntax of the SELECT statement

SELECT

column_1, column_2, ...

FROM

table_1

WHERE

conditions

ORDER BY column_1 ;

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ตอ้งการขอ้มูลจาก 3 fields คือ lastName, firstName และ jobTitle

SELECT Statement

SELECT

lastname, firstname, jobtitle

FROM

employees;

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SELECT Statement

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Introduction to ORDER BY clause

SELECT column1, column2,...

FROM tbl

ORDER BY column1 [ASC|DESC], column2 [ASC|DESC],...

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Example of ORDER BY clause

SELECT

contactLastname, contactFirstname

FROM

customers

ORDER BY contactLastname;

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Example of ORDER BY clause

SELECT

contactLastname, contactFirstname

FROM

customers

ORDER BY contactLastname DESC;

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Example of ORDER BY clause

SELECT

ordernumber, orderlinenumber, FORMAT(quantityOrdered * priceEach, 2)

FROM

orderdetails

ORDER BY ordernumber , orderLineNumber, quantityOrdered * priceEach;

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Example of ORDER BY clause

SELECT

orderNumber, status

FROM

orders

ORDER BY FIELD (status, 'In Process', 'On Hold', 'Cancelled', 'Resolved', 'Disputed', 'Shipped');

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Using DISTINCT to Eliminate Duplicates

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syntax of using the DISTINCT clause

SELECT DISTINCT

columns

FROM

table_name

WHERE

where_conditions;

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DISTINCT example 1

SELECT

lastname

FROM

employees

ORDER BY lastname;

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DISTINCT example 2

SELECT DISTINCT

lastname

FROM

employees

ORDER BY lastname;

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DISTINCT with multiple columns

SELECT DISTINCT

state, city

FROM

customers

WHERE

state IS NOT NULL

ORDER BY state , city;

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DISTINCT with multiple columns

SELECT DISTINCT

state, city

FROM

customers

WHERE

state IS NOT NULL

ORDER BY state , city;

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DISTINCT and aggregate function

SELECT

COUNT(DISTINCT state)

FROM

customers

WHERE

country = 'USA';

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Introduction to LIMIT clause

the LIMIT clause syntax with two arguments…

SELECT

column1,column2,...

FROM

table

LIMIT offset , count;

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Using LIMIT to get the first N rows

You can use the LIMIT clause to select the first N rows in a table, for example…

SELECT

customernumber, customername, creditlimit

FROM

customers

LIMIT 10;

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Using LIMIT to get the highest values

SELECT

customernumber, customername, creditlimit

FROM

customers

ORDER BY creditlimit DESC

LIMIT 5;

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Using LIMIT to get the lowest values

SELECT

customernumber, customername, creditlimit

FROM

customers

ORDER BY creditlimit ASC

LIMIT 5;

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Using LIMIT to get the lowest values

SELECT

customernumber, customername, creditlimit

FROM

customers

ORDER BY creditlimit ASC

LIMIT 5;

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BETWEEN Operator Explained

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Introduction to BETWEEN Operator

The BETWEEN operator allows you to specify a range to test. We often use the BETWEEN operator in the WHEREclause of the SELECT, INSERT, UPDATE, and DELETEstatements.

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syntax of the BETWEEN operator:

expr [NOT] BETWEEN begin_expr AND end_expr;

BETWEEN with number examples

SELECT

productCode, productName, buyPrice

FROM

products

WHERE

buyPrice BETWEEN 90 AND 100;

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BETWEEN with number examples

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BETWEEN with number examples 2

SELECT

productCode, productName, buyPrice

FROM

products

WHERE

buyPrice >= 90 AND buyPrice <= 100;

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BETWEEN with number examples 3

SELECT

productCode, productName, buyPrice

FROM

products

WHERE

buyPrice NOT BETWEEN 20 AND 100;

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BETWEEN with number examples 4

SELECT

productCode, productName, buyPrice

FROM

products

WHERE

buyPrice < 20 OR buyPrice > 100;

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Using LIKE Operator To Select Data Based

• The percentage ( % ) wildcard allows you to match any string of zero or more characters.

• The underscore ( _ ) wildcard allows you to match any single character.

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LIKE with percentage (%) wildcard

SELECT

employeeNumber, lastName, firstName

FROM

employees

WHERE

firstName LIKE 'a%';

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LIKE with percentage (%) wildcard 2

SELECT

employeeNumber, lastName, firstName

FROM

employees

WHERE

lastName LIKE '%on';

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LIKE with percentage (%) wildcard 3

SELECT

employeeNumber, lastName, firstName

FROM

employees

WHERE

lastName LIKE '%on%';

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LIKE with underscore( _ ) wildcard

SELECT

employeeNumber, lastName, firstName

FROM

employees

WHERE

firstName LIKE 'T_m';

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LIKE operator with NOT operator

SELECT

employeeNumber, lastName, firstName

FROM

employees

WHERE

lastName NOT LIKE 'B%';

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Introducing to GROUP BY clause

The following illustrates the GROUP BY clause syntax:

SELECT c1, c2,..., cn, aggregate_function(ci)

FROM table

WHERE where_conditions

GROUP BY c1 , c2,...,cn;

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Simple GROUP BY example 1

SELECT

status

FROM

orders

GROUP BY status;

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GROUP BY with aggregate functions

SELECT

status, COUNT(*)

FROM

orders

GROUP BY status;

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Simple GROUP BY example 2

SELECT

status, COUNT(*)

FROM

orders

GROUP BY status DESC;

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