Structured Query Language

NEU – CCIS – CSU430Tony

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Content

Select queries on one table Select queries on multiple tables Manipulate data and table

structure

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0. References

CAPS database on textbook P27-28 http://www.sql.org/

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1. Select queries on one table

Simple queries Distinct Aggregate functions Sorting query results Like\Between … And Group Alias

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1.1 Simple queries

List all records in products select * from products

List all records in records in customers

select * from customers

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1.1 Simple queries (cont) List all product names in the product tableselect pname from productsproduct[pname] (Projection) ??

List all customer names in the customers table

select cname from customerscustomers[cname] (Projection)

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1.1 Simple query (cont)

List all customer records in Dallasselect * from customers where city =

'Dallas‘customers where city = ‘Dallas`

List all order records costs more than 800select * from orders where dollars > 800orders where dollars > 800

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1.1 Simple query (cont)

List all customer names in Dallasselect cname from customers where city

= 'Dallas‘

List the order number, quantity of orders cost more than 800

select ordno, qty from orders where dollars > 800

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1.2 Distinct

List all customer names in the customers table

select cname from customerscustomers[cname] (Not Projection)

select distinct cname from customerscustomers[cname] (Projection)

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1.2 Distinct (cont)

List all distinct agent names

select aname from agents

select distinct aname from agents

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1.3 Aggregate functions

List the total cost of all ordersselect sum(dollars) from orders

List the total cost of client c001select sum(dollars) from orders where

cid = 'c001'

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1.3 Aggregate functions (cont)

List the average discount of all customers

select avg(discnt) from customers

List the average discount of customers in Duluth area

select avg(discnt) from customers where city = 'Duluth'

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1.3 Aggregate functions (cont)

Most frequent-used aggregate functions

SumAvgCountMinMax… see online documents

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1.4 Sort query results List the product names and prices in price

ascending orderselect pname, price from products order by

price

List the product names and prices in price descending order

select pname, price from products order by price desc

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1.5 Like \ Between … And Find all customers in the cities start with letter “D”.select * from customers where city like 'D%‘

Find all products whose name end with letter “r”.select * from products where pname like '%r‘

Find all the agents whose names contain letter “r”.select * from agents where aname like '%r%'

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1.5 Like \ Between … And (cont) List all orders that cost between 500 and

1000select * from orders where dollars between 500

and 1000

List all customers whose discount between 5 and 10

select * from customers where discnt between 5 and 10

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1.6 Group

Find the total expense of each client

Straightforward solutions:Select sum(dollars) from orders where

cid = ‘c001’Select sum(dollars) from orders where

cid = ‘c002’ ……

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1.6 Group (cont)

Find the total expense of each client

Select cid,sum(dollars) from orders group by cid

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1.6 Group (cont)

Find total sales amount of each agent

Select aid,sum(dollars) from orders group by aid

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1.6 Group (cont)

Find total sales amount of each agent whose total sales amount is more than 1000 dollars.

Select aid,sum(dollars) from orders group by aid where sum(dollars) > 1000

Select aid,sum(dollars) from orders group by aid having sum(dollars) > 1000

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1.6 Group (cont)

Find total expense of each client whose total expense is more than 1000 dollars.

Select cid,sum(dollars) from orders group by cid having sum(dollars) > 1000

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1.6 Group (cont) Find the total expense of each client on

each product

Select pid,cid,sum(dollars) from orders group by cid

Fields cannot have multi-values attributes or have any internal structures (First Normal Form Rule).

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1.6 Group (cont)

Find the total expense of each client on each product

Select pid,cid,sum(dollars) from orders group by pid,cid

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1.7 Alias and calculated field

Find total expense of each client whose total expense is more than 1000 dollars

Select cid as client_id, sum(dollars) as total_cost_per_client from orders group by cid having sum(dollars) > 1000

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1.7 Alias (cont)

Find all orders more expensive than 1000 dollars.

Select * from orders o where o.dollars > 1000