2 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. SaleAnimal SaleID AnimalID SalePrice. Customer.

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1 Advanced Queries IS240 DBMS Lecture # M. E. Kabay, PhD, CISSP-ISSMP Assoc. Prof. Information Assurance Division of Business & Management, Norwich University mailto:mkabay@norwich.edu V: Topics Sub-query for Calculation Query Sets (IN) Using IN with a Sub-query Left Outer Join Older Syntax for Left Join SubQuery for Computation Correlated Subquery UNION Operator Multiple JOIN Columns CASE Function Inequality Join SQL SELECT & SQL Mnemonic 1 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. 2 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. Supplier Contact Tables der derid derdate ReceiveDate ShippingCost City City State AreaCode Population1990 Population1980 Country Latitude Longitude Merchandise der PONumber derdate ReceiveDate ShippingCost 3 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. deritem derid Cost Employee Last First TaxPayerID DateHired DateReleased deritem PONumber Cost Registration DateBorn Gender Registered Color ListPrice Photo Date stax Merchandise Description OnHand ListPrice First Last Item Harder Questions How many cats are instock on 10/1/04? Which cats sold for more than the average price? Which animals sold for more than the average price of animals in their category? Which animals have not been sold? Which customers (who bought something at least once) did not buy anything between 11/1/04 and 12/31/04? Which customers who bought Dogs also bought products for Cats (at any time)? 4 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. Sub-query for Calculation Which cats sold for more than the average sale price of cats? Assume we know the average price is $170. Usually we need to compute it first. SELECT.,.,. INNER JOIN ON. =. WHERE ((.= Cat ) AND (.>170)); SELECT.,.,. INNER JOIN ON. =. WHERE ((.= Cat ) AND (.> ( SELECT AVG() INNER JOIN ON. =. WHERE (.= Cat ) ) ) ); Query Sets (IN) SELECT.Last,.First, Item. FROM ( INNER JOIN ON. =.) INNER JOIN Item ON. = Item. WHERE (Item. In (1,2,30,32,33)) ORDER BY.Last,.First; Item Date ID First Last Field Last First Table Item Ascending Ascending Criteria In (1,2,30,32,33) List all customers () who purchased one of the following items: 1, 2, 30, 32, Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. 6 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved.

2 Using IN with a Sub-query List all customers who bought items for cats. SELECT.Last,.First, Item. FROM ( INNER JOIN ON. =.) INNER JOIN Item ON. = Item. WHERE (Item. In (SELECT ID FROM Merchandise WHERE = Cat ) t ) ); SubQuery (IN: Look up a Set) SELECT.Last,.First FROM INNER JOIN ON. =. WHERE ((Month([Date])=3)) And. In (SELECT FROM WHERE (Month([Date])=5) ); First Last Date Last First Adkins Inga McCain Sam Gi Grimes Earl Field Last First Month(Date) Table Ascending Ascending Criteria 3 In (SELECT FROM State WHERE (Month(Date)=5) List all of the customers who bought something in March and who also bought something in May. (Two tests on the same data!) 7 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. 8 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. SubQuery (ANY, ALL) Find animals that sold for more than any of the prices of cats (= find animals that sold for more than the greatest price of any cat) SELECT.,,, ListPrice INNER JOIN ON. =. WHERE (( > Any (SELECT ListPrice INNER JOIN ON. =. WHERE = Cat )) AND (= Cat ); Any: value is compared to each item in the list. If it is True for any of the items, the statement is evaluated to True. All: value is compared to each item in the list. If it is True for every item in the list, the statement is evaluated to True (much more restrictive than any). 9 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. SubQuery: NOT IN (Subtract) SELECT.,.,. WHERE (. Not In (SELECT From )); Field Table Criteria Not In (SELECT FROM ) Start with list of all animals. Subtract out list of those who were sold. 10 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. 12 Leisha Dog 19 Gene Dog 25 Vivian Dog 34 Rhonda Dog 88 Brandy Dog 181 Fish SELECT.,,, ListPrice INNER JOIN ON. =.. SubQuery: NOT IN (Data) ID 2 Fish Angel 4 Gary Dog Dalmation 5 Fish Shark 6 Rosie Cat iental Shorthair 7 Eugene Cat Bombay 8 Miranda Dog Norfolk Terrier 9 Fish Guppy 10 Sherri Dog Siberian i Huskie 11 Susan Dog Dalmation 12 Leisha Dog Rottweiler 11 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. ID 2 35 $ $ $ $ $ $ $ SELECT.,.,. WHERE (. Not In (SELECT From )); Start with list of all animals. Subtract out list of those who were sold. Left Outer Join SELECT.,.,.,. LEFT JOIN ON. =. WHERE (. Is Null); 12 Leisha Dog 19 Gene Dog 25 Vivian Dog 34 Rhonda Dog 88 Brandy Dog 181 Fish Field Table Criteria Is Null LEFT JOIN includes all rows from left table () But only those from right table () that match a row in on. Thus rows in without matching data in will have Null data for. and. 12 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. FROM INNER JOIN ON. =.

3 Left Outer Join (Example) ID 2 Fish Angel 4 Gary Dog Dalmation 5 Fish Shark 6 Rosie Cat iental Shorthair 7 Eugene Cat Bombay 8 Miranda Dog Norfolk Terrier 9 Fish Guppy 10 Sherri Dog Siberian Huskie 11 Susan Dog Dalmation a 12 Leisha Dog Rottweiler ID 2 35 $ $ $ $ $ $ $ SubQuery for Computation SELECT.,.,. INNER JOIN ON. =. WHERE ((.= Cat ) AND (.> ( SELECT AVG() INNER JOIN ON. =. WHERE (.= Cat ) ) ) ); Don t know the average, so use a subquery to compute it. Watch parentheses. Field Table Descending Criteria 3 > (SELECT Avg() INNER JOIN ON. =. WHERE. = Cat ) 13 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. 14 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. Correlated Subquery List the s that have sold for a price higher than the average for animals in that. SELECT,,, INNER JOIN ON. =. WHERE (.> (SELECT Avg(.) INNER JOIN ON. =. WHERE (. =.) ) ) ORDER BY. DESC; The subquery needs to compute the average for a given category. Problem: Which category? Answer: the category that matches the category from the main part of the query. Problem: How do we refer to it? Both tables are called. This query will not work yet. Correlated SubQuery (Avoid) Match category in subquery with top level Rename tables (As) Correlated Subquery Recompute subquery for every row in top level--slow! Better to compute and save Subquery, then use in join. SELECT A1., A1., A1.,. As A1 INNER JOIN ON A1. =. WHERE (.> (SELECT Avg(.) As A2 INNER JOIN This is recomputed ON A2. =. for every new WHERE (A2. = A1.) ) ) category ORDER BY. DESC; List the s that have sold for a price higher than the average for animals in that. 15 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. 16 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. Correlated Subquery Problem + Fish $10.80 Dog $ Fish $19.80 Cat $ Cat $ Dog $ Fish $1.80 Dog $ Dog $ Compute Avg: $37.78 Compute Avg: $ Compute Avg: $37.78 Compute Avg: $ Compute Avg: $ Recompute average for every row in the main query! More Efficient Solution: 2 queries + Fish $10.80 Dog $ Fish $19.80 Cat $ Cat $ Dog $ Fish $1.80 Dog $ Dog $ JOIN. = Query1. Saved Query AvgOf Bird $ Cat $ Dog $ Fish $37.78 Mammal $80.72 Reptile $ Spider $ Assume small query 100,000 rows 5 categories of 20,000 rows 100,000 * 20,000 = 1 billion rows to read! Compute the averages once and save query JOIN saved query to main query Two passes through table: 1 billion / 200,000 => 10, Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. 18 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved.

4 UNION Operator SELECT EID,,, Salary, East AS Office FROM EmployeeEast UNION SELECT EID,,, Salary, West AS Office FROM EmployeeWest EID Salary Office 352 Jones ,000 East 876 Inez ,000 East 372 Stoiko ,000 East 890 Smythe ,000 West 361 Kim ,000 West Offices in Los Angeles and New York. Each has an Employee table (East and West). Need to search data from both tables. Columns in the two SELECT lines must match. UNION, INTERSECT, EXCEPT A B C T1 T2 T1 UNION T2 T1 INTERSECT T2 T1 EXCEPT T2 A + B + C B A List the name of any employee who has worked for both the East and West regions. SELECT EID, FROM EmployeeEast INTERSECT SELECT EID, FROM EmployeeWest 19 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. 20 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. Multiple JOIN Columns DateBorn Gender... SELECT * FROM INNER JOIN ON. =. AND. =. Reflexive Join SQL SELECT Employee.EID, Employee., Employee.Manager, E2. FROM Employee INNER JOIN Employee AS E2 ON Employee.Manager = E2.EID EID Employee EID... Manager 115 Sanchez Miller Hawk Munoz 886 Result EID Manager 115 Sanchez 765 Munoz 462 Miller 115 Sanchez 523 Hawk 115 Sanchez Sometimes need to JOIN tables on more than one column. PetStore: and. 21 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. Need to connect a table to itself. Common example: Employee(EID,,..., Manager) A manager is also an employee. Use a second copy of the table and an alias. 22 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. CASE Function Select, CASE WHEN Date()-DateBorn < 90 Then Baby WHEN Date()-DateBorn >= 90 AND Date()-DateBorn < 270 Then Young WHEN Date()-DateBorn >= 270 AND Date()-DateBorn < 365 Then Grown ELSE Experienced END ; Not available in Microsoft Access. It is in SQL Server and acle. Used to change data to a different context. Example: Define age categories for the animals. Less than 3 months Between 3 months and 9 months Between 9 months and 1 year Over 1 year Inequality Join AccountsReceivable ( AR ) Categorize by Days Late 30, 90, 120+ Three queries? Better: JOIN to new table for business rules AR(TransactionID,, Amount, DateDue) Late(, t t MinDays, MaxDays, Charge, ) Month % Quarter % Overdue % SELECT * FROM AR INNER JOIN Late ON ((Date() - AR.DateDue) >= Late.MinDays) AND ((Date() - AR.DateDue) < Late.MaxDays) 23 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. 24 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved.

5 SQL SELECT: REVIEW SELECT DISTINCT Table.Column {AS alias},... FROM Table/Query INNER JOIN Table/Query ON T1.ColA = T2.ColB WHERE (condition) GROUP BY Column HAVING (group condition) ORDER BY Table.Column { Union second select } SQL Mnemonic Someone SELECT From FROM Ireland INNER JOIN Will WHERE Grow GROUP BY Horseradish and HAVING Onions ORDER BY SQL is picky about putting the commands in the proper sequence. If you have to memorize the sequence, this mnemonic may be helpful. 25 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. 26 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. Homework Study Chapter 5 pp carefully using SQ3R Use the Review Questions 1-8 on pp to challenge yourselves. Recommended exercises: Sally s Pets: previous classes completed all 25 of these exercises within two weeks and sweated blood to do so You can tackle them without pressure. Do at least the first 10 to apply the theory USE THE SQL INTERPRETER IN MS-ACCESS TO TEST ALL YOUR QUERIES Solutions will be distributed after the Spring Break. DISCUSSION 27 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved. 28 Copyright 2010 Jerry Post with additions & narration by M. E. Kabay. All rights reserved.