Relational Algebra and Calculus: Introduction to SQL
description
Transcript of Relational Algebra and Calculus: Introduction to SQL
![Page 1: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/1.jpg)
2013-09-17 SLIDE 1IS 257 – Fall 2013
Relational Algebra and Calculus:Introduction to SQLUniversity of California, Berkeley
School of InformationIS 257: Database Management
![Page 2: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/2.jpg)
2013-09-17 SLIDE 2IS 257 – Fall 2013
Announcements
![Page 3: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/3.jpg)
2013-09-17 SLIDE 3IS 257 – Fall 2013
Lecture Outline• Review
–Logical Design and Normalization• Relational Algebra• Relational Calculus• Introduction to SQL
![Page 4: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/4.jpg)
2013-09-17 SLIDE 4IS 257 – Fall 2013
Lecture Outline• Review
–Logical Design and Normalization• Relational Algebra• Relational Calculus• Introduction to SQL
![Page 5: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/5.jpg)
2013-09-17 SLIDE 5IS 257 – Fall 2013
Normalization• Normalization theory is based on the
observation that relations with certain properties are more effective in inserting, updating and deleting data than other sets of relations containing the same data
• Normalization is a multi-step process beginning with an “unnormalized” relation– Hospital example from Atre, S. Data Base:
Structured Techniques for Design, Performance, and Management.
![Page 6: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/6.jpg)
2013-09-17 SLIDE 6IS 257 – Fall 2013
Normal Forms• First Normal Form (1NF)• Second Normal Form (2NF)• Third Normal Form (3NF)• Boyce-Codd Normal Form (BCNF)• Fourth Normal Form (4NF)• Fifth Normal Form (5NF)
![Page 7: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/7.jpg)
2013-09-17 SLIDE 7IS 257 – Fall 2013
Normalization
Boyce-Codd and
Higher
Functional dependencyof nonkey attributes on the primary key - Atomic values only
Full Functional dependencyof nonkey attributes on the primary key
No transitive dependency between nonkey attributes
All determinants are candidate keys - Single multivalued dependency
![Page 8: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/8.jpg)
2013-09-17 SLIDE 8IS 257 – Fall 2013
Normalizing to death• Normalization splits database information
across multiple tables.• To retrieve complete information from a
normalized database, the JOIN operation must be used.
• JOIN tends to be expensive in terms of processing time, and very large joins are very expensive.
![Page 9: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/9.jpg)
2013-09-17 SLIDE 9IS 257 – Fall 2013
Downward DenormalizationCustomer
IDAddressNameTelephone
Order Order NoDate TakenDate DispatchedDate InvoicedCust ID
Before:Customer
IDAddressNameTelephone
Order Order NoDate TakenDate DispatchedDate InvoicedCust IDCust Name
After:
![Page 10: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/10.jpg)
2013-09-17 SLIDE 10IS 257 – Fall 2013
Upward DenormalizationOrder
Order NoDate TakenDate DispatchedDate InvoicedCust IDCust NameOrder Price
Order Item Order NoItem NoItem PriceNum Ordered
Order Order NoDate TakenDate DispatchedDate InvoicedCust IDCust Name
Order Item Order NoItem NoItem PriceNum Ordered
![Page 11: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/11.jpg)
2013-09-17 SLIDE 11IS 257 – Fall 2013
Denormalization• Usually driven by the need to improve
query speed• Query speed is improved at the expense
of more complex or problematic DML (Data manipulation language) for updates, deletions and insertions.
![Page 12: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/12.jpg)
2013-09-17 SLIDE 12IS 257 – Fall 2013
Using RDBMS to help normalize• Example database: Cookie• Database of books, libraries, publisher and
holding information for a shared (union) catalog
![Page 13: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/13.jpg)
2013-09-17 SLIDE 13IS 257 – Fall 2013
Cookie relationships
![Page 14: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/14.jpg)
2013-09-17 SLIDE 14IS 257 – Fall 2013
Cookie BIBFILE relation
![Page 15: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/15.jpg)
2013-09-17 SLIDE 15IS 257 – Fall 2013
How to Normalize?• Currently no way to have multiple authors
for a given book, and there is duplicate data spread over the BIBFILE table
• Can we use the DBMS to help us normalize?
• It is possible (but takes a bit more SQL knowledge than has been hinted at so far)– We will return to this problem later– But CONCEPTUALLY…
![Page 16: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/16.jpg)
2013-09-17 SLIDE 16IS 257 – Fall 2013
Using RDBMS to NormalizeCreate a new table for Authors that includes author
name and an automatically incrementing id number (for primary key)
Populate the table using the unique author names (which get assigned id numbers) by extracting them from the BIBFILE
Create a new table containing a author_id and an ACCNO
Populate the new table by matching the Authors and BIBFILE names
Drop the Author name column from BIBFILE
![Page 17: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/17.jpg)
2013-09-17 SLIDE 17IS 257 – Fall 2013
Advantages of RDBMS• Relational Database Management
Systems (RDBMS)• Possible to design complex data storage
and retrieval systems with ease (and without conventional programming).
• Support for ACID transactions– Atomic – Consistent– Independent– Durable
![Page 18: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/18.jpg)
2013-09-17 SLIDE 18IS 257 – Fall 2013
Advantages of RDBMS• Support for very large databases• Automatic optimization of searching (when
possible)• RDBMS have a simple view of the
database that conforms to much of the data used in business
• Standard query language (SQL)
![Page 19: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/19.jpg)
2013-09-17 SLIDE 19IS 257 – Fall 2013
Disadvantages of RDBMS• Until recently, no real support for complex
objects such as documents, video, images, spatial or time-series data. (ORDBMS add -- or make available support for these)
• Often poor support for storage of complex objects from OOP languages (Disassembling the car to park it in the garage)
• Usually no efficient and effective integrated support for things like text searching within fields (MySQL does have simple keyword searching now with index support)
![Page 20: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/20.jpg)
2013-09-17 SLIDE 20IS 257 – Fall 2013
Lecture Outline• Review
–Logical Design and Normalization• Relational Algebra• Relational Calculus• Introduction to SQL
![Page 21: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/21.jpg)
2013-09-17 SLIDE 21IS 257 – Fall 2013
Relational Algebra• Relational Algebra is a collection of
operators that take relations as their operands and return a relation as their results
• First defined by Codd– Include 8 operators
• 4 derived from traditional set operators• 4 new relational operations
From: C.J. Date, Database Systems 8th ed.
![Page 22: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/22.jpg)
2013-09-17 SLIDE 22IS 257 – Fall 2013
Relational Algebra Operations• Restrict• Project• Product• Union• Intersect• Difference• Join• Divide
![Page 23: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/23.jpg)
2013-09-17 SLIDE 23IS 257 – Fall 2013
Restrict• Extracts specified tuples (rows) from a
specified relation (table) – Restrict is AKA “Select”
![Page 24: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/24.jpg)
2013-09-17 SLIDE 24IS 257 – Fall 2013
Project• Extracts specified attributes(columns) from
a specified relation.
![Page 25: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/25.jpg)
2013-09-17 SLIDE 25IS 257 – Fall 2013
Product• Builds a relation from two specified
relations consisting of all possible concatenated pairs of tuples, one from each of the two relations. (AKA Cartesian Product)
abc
xy
xyxyxy
aabbcc
Product
![Page 26: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/26.jpg)
2013-09-17 SLIDE 26IS 257 – Fall 2013
Union• Builds a relation consisting of all tuples
appearing in either or both of two specified relations.
![Page 27: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/27.jpg)
2013-09-17 SLIDE 27IS 257 – Fall 2013
Intersect• Builds a relation consisting of all tuples
appearing in both of two specified relations
![Page 28: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/28.jpg)
2013-09-17 SLIDE 28IS 257 – Fall 2013
Difference• Builds a relation consisting of all tuples
appearing in first relation but not the second.
![Page 29: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/29.jpg)
2013-09-17 SLIDE 29IS 257 – Fall 2013
Join• Builds a relation from two specified
relations consisting of all possible concatenated pairs, one from each of the two relations, such that in each pair the two tuples satisfy some condition. (E.g., equal values in a given col.)
A1 B1A2 B1A3 B2
B1 C1B2 C2B3 C3
A1 B1 C1A2 B1 C1A3 B2 C2
(Naturalor Inner)
Join
![Page 30: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/30.jpg)
2013-09-17 SLIDE 30IS 257 – Fall 2013
Outer Join• Outer Joins are similar to PRODUCT -- but
will leave NULLs for any row in the first table with no corresponding rows in the second.
A1 B1A2 B1A3 B2A4 B7
B1 C1B2 C2B3 C3
A1 B1 C1A2 B1 C1A3 B2 C2A4 * *
Outer Join
![Page 31: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/31.jpg)
2013-09-17 SLIDE 31IS 257 – Fall 2013
Divide• Takes two relations, one binary and one
unary, and builds a relation consisting of all values of one attribute of the binary relation that match (in the other attribute) all values in the unary relation.
a
xy
xyzxy
aaabc
Divide
![Page 32: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/32.jpg)
2013-09-17 SLIDE 32IS 257 – Fall 2013
ER Diagram: Acme Widget Co.
Contains Part
Part# Count
Price
Customer
Quantity
Orders
Cust#
Invoice
Writes
Sales-Rep
Invoice#
Sales
Rep#
Line-ItemContains
Part#
Invoice#
Cust#
Hourly
Employee
ISA
Emp#Wage
![Page 33: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/33.jpg)
2013-09-17 SLIDE 33IS 257 – Fall 2013
Employee
![Page 34: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/34.jpg)
2013-09-17 SLIDE 34IS 257 – Fall 2013
Part
![Page 35: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/35.jpg)
2013-09-17 SLIDE 35IS 257 – Fall 2013
Sales-Rep
Hourly
![Page 36: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/36.jpg)
2013-09-17 SLIDE 36IS 257 – Fall 2013
Customer
![Page 37: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/37.jpg)
2013-09-17 SLIDE 37IS 257 – Fall 2013
Invoice
![Page 38: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/38.jpg)
2013-09-17 SLIDE 38IS 257 – Fall 2013
Line-Item
![Page 39: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/39.jpg)
2013-09-17 SLIDE 39IS 257 – Fall 2013
Join Items
![Page 40: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/40.jpg)
2013-09-17 SLIDE 40IS 257 – Fall 2013
Relational Algebra• What is the name of the customer who
ordered Large Red Widgets?– Restrict “large Red Widgets” row from Part as
temp1– Join temp1 with Line-item on Part # as temp2– Join temp2 with Invoice on Invoice # as temp3– Join temp3 with Customer on cust # as temp4– Project Company from temp4 as answer
![Page 41: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/41.jpg)
2013-09-17 SLIDE 41IS 257 – Fall 2013
Lecture Outline• Review
–Logical Design and Normalization• Relational Algebra• Relational Calculus• Introduction to SQL
![Page 42: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/42.jpg)
2013-09-17 SLIDE 42IS 257 – Fall 2013
Relational Calculus• Relational Algebra provides a set of explicit
operations (select, project, join, etc) that can be used to build some desired relation from the database
• Relational Calculus provides a notation for formulating the definition of that desired relation in terms of the relations in the database without explicitly stating the operations to be performed
• SQL is based on the relational calculus and algebra
![Page 43: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/43.jpg)
2013-09-17 SLIDE 43IS 257 – Fall 2013
Lecture Outline• Review
–Logical Design and Normalization• Relational Algebra• Relational Calculus• Introduction to SQL
![Page 44: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/44.jpg)
2013-09-17 SLIDE 44IS 257 – Fall 2013
SQL• Structured Query Language• Used for both Database Definition,
Modification and Querying• Basic language is standardized across
relational DBMS’s. Each system may have proprietary extensions to standard.
• Relational Calculus combines Restrict, Project and Join operations in a single command. SELECT.
![Page 45: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/45.jpg)
2013-09-17 SLIDE 45IS 257 – Fall 2013
SQL - History • QUEL (Query Language from Ingres)• SEQUEL from IBM San Jose• ANSI 1992 Standard is the version used
by most DBMS today (SQL92)• Basic language is standardized across
relational DBMSs. Each system may have proprietary extensions to the standard.
![Page 46: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/46.jpg)
2013-09-17 SLIDE 46IS 257 – Fall 2013
SQL99• In 1999, SQL:1999 – also known as SQL3 and
SQL99 – was adopted and contains the following eight parts: – The SQL/Framework (75 pages)– SQL/Foundation (1100 pages)– SQL/Call Level Interface (400 pages)– SQL/Persistent Stored Modules (PSM) (160 pages)– SQL/Host Language Bindings (250 pages)– SQL Transactions (??)– SQL Temporal objects (??)– SQL Objects (??)
• Designed to be compatible with SQL92
![Page 47: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/47.jpg)
2013-09-17 SLIDE 47IS 257 – Fall 2013
SQL:2003 & 2006• Further additions to the standard including XML
support and Java bindings, as well as finally standardizing autoincrement data
• ISO/IEC 9075-14:2006 defines ways in which SQL can be used in conjunction with XML. – It defines ways of importing and storing XML data in
an SQL database, manipulating it within the database and publishing both XML and conventional SQL-data in XML form.
– In addition, it provides facilities that permit applications to integrate into their SQL code the use of XQuery, the XML Query Language published by the World Wide Web Consortium (W3C), to concurrently access ordinary SQL-data and XML documents.
From the ISO/IEC web site
![Page 48: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/48.jpg)
2013-09-17 SLIDE 48
SQL 2008 & 2011?• 2008: Legalizes ORDER BY outside
cursor definitions. Adds INSTEAD OF triggers. Adds the TRUNCATE statement
• (2011 still in progress – in 2013)
IS 257 – Fall 2013
![Page 49: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/49.jpg)
2013-09-17 SLIDE 49IS 257 – Fall 2013
SQL:1999• The SQL/Framework --SQL basic
concepts and general requirements. • SQL/Call Level Interface (CLI) -- An API
for SQL. This is similar to ODBC. • SQL/Foundation --The syntax and SQL
operations that are the basis for the language.
![Page 50: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/50.jpg)
2013-09-17 SLIDE 50IS 257 – Fall 2013
SQL99• SQL/Persistent Stored Modules (PSM) --
Defines the rules for developing SQL routines, modules, and functions such as those used by stored procedures and triggers. This is implemented in many major RDBMSs through proprietary, nonportable languages, but for the first time we have a standard for writing procedural code that is transportable across databases.
![Page 51: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/51.jpg)
2013-09-17 SLIDE 51IS 257 – Fall 2013
SQL99• SQL/Host Language Bindings --Define ways to
code embedded SQL in standard programming languages. This simplifies the approach used by CLIs and provides performance enhancements.
• SQL Transactions --Transactional support for RDBMSs.
• SQL Temporal objects --Deal with Time-based data.
• SQL Objects --The new Object-Relational features, which represent the largest and most important enhancements to this new standard.
![Page 52: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/52.jpg)
2013-09-17 SLIDE 52IS 257 – Fall 2013
SQL99 (Builtin) Data TypesSQL
Data Types
Ref TypesPredefinedTypes Arrays ROW
Data StructUser-Defined
Types
Numeric String DateTime Interval Boolean
Date
Time
Timestamp
Bit Character Blob
Fixed
Varying
CLOB
Fixed
Varying
ApproximateExact
NEWIN SQL99
![Page 53: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/53.jpg)
2013-09-17 SLIDE 53IS 257 – Fall 2013
SQL Uses• Database Definition and Querying
– Can be used as an interactive query language– Can be imbedded in programs
• Relational Calculus combines Select, Project and Join operations in a single command: SELECT
![Page 54: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/54.jpg)
2013-09-17 SLIDE 54IS 257 – Fall 2013
SELECT• Syntax:
SELECT [DISTINCT] attr1, attr2,…, attr3 FROM rel1 r1, rel2 r2,… rel3 r3 WHERE condition1 {AND | OR} condition2 ORDER BY attr1 [DESC], attr3 [DESC]
![Page 55: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/55.jpg)
2013-09-17 SLIDE 55IS 257 – Fall 2013
SELECT• Syntax:
SELECT a.author, b.title FROM authors a, bibfile b, au_bib c WHERE a.AU_ID = c.AU_ID and c.accno = b.accno ORDER BY a.author ;
• Examples in Access...
![Page 56: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/56.jpg)
2013-09-17 SLIDE 56IS 257 – Fall 2013
SELECT Conditions
• = equal to a particular value• >= greater than or equal to a particular value• > greater than a particular value• <= less than or equal to a particular value• <> not equal to a particular value• LIKE “*term*” (may be other wild cards in
other systems)• IN (“opt1”, “opt2”,…,”optn”)• BETWEEN val1 AND val2• IS NULL
![Page 57: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/57.jpg)
2013-09-17 SLIDE 57IS 257 – Fall 2013
Relational Algebra Selection using SELECT
• Syntax:
SELECT * WHERE condition1 {AND | OR} condition2;
![Page 58: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/58.jpg)
2013-09-17 SLIDE 58IS 257 – Fall 2013
Relational Algebra Projection using SELECT
• Syntax:
SELECT [DISTINCT] attr1, attr2,…, attr3 FROM rel1 r1, rel2 r2,… rel3 r3;
![Page 59: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/59.jpg)
2013-09-17 SLIDE 59IS 257 – Fall 2013
Relational Algebra Join using SELECT
• Syntax:
SELECT * FROM rel1 r1, rel2 r2 WHERE r1.linkattr = r2.linkattr ;
![Page 60: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/60.jpg)
2013-09-17 SLIDE 60IS 257 – Fall 2013
Sorting• SELECT BIOLIFE.`Common Name`,
BIOLIFE.`Length (cm)` FROM BIOLIFE ORDER BY BIOLIFE.`Length (cm)` DESC;
![Page 61: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/61.jpg)
2013-09-17 SLIDE 61IS 257 – Fall 2013
Subqueries• SELECT SITES.`Site Name`,
SITES.`Destination no` FROM SITES WHERE sites.`Destination no` IN
(SELECT `Destination no` from DEST where `avg temp (f)` >= 78);
• Can be used as a form of JOIN.
![Page 62: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/62.jpg)
2013-09-17 SLIDE 62IS 257 – Fall 2013
Aggregate Functions• Count• Avg• SUM• MAX• MIN• Many others are available in different
systems
![Page 63: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/63.jpg)
2013-09-17 SLIDE 63IS 257 – Fall 2013
Using Aggregate functions• SELECT attr1, Sum(attr2) AS name
FROM tab1, tab2 ... GROUP BY attr1, attr3 HAVING condition;
![Page 64: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/64.jpg)
2013-09-17 SLIDE 64IS 257 – Fall 2013
Using an Aggregate Function
• SELECT DIVECUST.Name, Sum(Rental_Price*qty) AS Total
FROM (DIVECUST INNER JOIN DIVEORDS ON DIVECUST.Customer_No = DIVEORDS.Customer_No) INNER JOIN DIVEITEM ON DIVEORDS.Order_No = DIVEITEM.Order_No
GROUP BY DIVECUST.Name HAVING ((DIVECUST.Name) LIKE ‘%Jazdzewski
%’);
![Page 65: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/65.jpg)
2013-09-17 SLIDE 65IS 257 – Fall 2013
GROUP BY• SELECT DEST.[Destination Name],
Count(*) AS Expr1 FROM DEST INNER JOIN DIVEORDS
ON DEST.[Destination Name] = DIVEORDS.Destination
GROUP BY DEST.[Destination Name] HAVING ((Count(*))>1);• Provides a list of Destinations with the
number of orders going to that destinationNote: the square brackets are not part of the standard,But are used in Access for names with embedded blanks
![Page 66: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/66.jpg)
2013-09-17 SLIDE 66IS 257 – Fall 2013
Create Table• CREATE TABLE table-name (attr1 attr-
type PRIMARYKEY, attr2 attr-type,…,attrN attr-type);– Adds a new table with the specified attributes
(and types) to the database.
• In MySQL (5.5+) – CREATE TABLE newtablename SELECT …
• Creates new table with contents from SELECT command including data types
![Page 67: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/67.jpg)
2013-09-17 SLIDE 67IS 257 – Fall 2013
Access Data Types
• Numeric (1, 2, 4, 8 bytes, fixed or float)• Text (255 max)• Memo (64000 max)• Date/Time (8 bytes)• Currency (8 bytes, 15 digits + 4 digits decimal)• Autonumber (4 bytes)• Yes/No (1 bit)• OLE (limited only by disk space)• Hyperlinks (up to 64000 chars)
![Page 68: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/68.jpg)
2013-09-17 SLIDE 68IS 257 – Fall 2013
Access Numeric types• Byte
– Stores numbers from 0 to 255 (no fractions). 1 byte• Integer
– Stores numbers from –32,768 to 32,767 (no fractions) 2 bytes
• Long Integer (Default) – Stores numbers from –2,147,483,648 to 2,147,483,647 (no
fractions). 4 bytes• Single
– Stores numbers from -3.402823E38 to –1.401298E–45 for negative values and from 1.401298E–45 to 3.402823E38 for positive values. 4 bytes
• Double– Stores numbers from –1.79769313486231E308 to –
4.94065645841247E–324 for negative values and from 1.79769313486231E308 to 4.94065645841247E–324 for positive values. 15 8 bytes
• Replication ID– Globally unique identifier (GUID) N/A 16 bytes
![Page 69: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/69.jpg)
2013-09-17 SLIDE 69IS 257 – Fall 2013
Oracle Data Types
• CHAR (size) -- max 2000• VARCHAR2(size) -- up to 4000• DATE• DECIMAL, FLOAT, INTEGER, INTEGER(s),
SMALLINT, NUMBER, NUMBER(size,d)– All numbers internally in same format…
• LONG, LONG RAW, LONG VARCHAR– up to 2 Gb -- only one per table
• BLOB, CLOB, NCLOB -- up to 4 Gb• BFILE -- file pointer to binary OS file
![Page 70: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/70.jpg)
2013-09-17 SLIDE 70IS 257 – Fall 2013
Creating a new table from existing tables
• Access and PostgreSQL Syntax:
SELECT [DISTINCT] attr1, attr2,…, attr3 INTO newtablename FROM rel1 r1, rel2 r2,… rel3 r3 WHERE condition1 {AND | OR} condition2 ORDER BY attr1 [DESC], attr3 [DESC]
![Page 71: Relational Algebra and Calculus: Introduction to SQL](https://reader035.fdocuments.us/reader035/viewer/2022062222/568164c5550346895dd6dcbf/html5/thumbnails/71.jpg)
2013-09-17 SLIDE 71IS 257 – Fall 2013
How to do it in MySQLmysql> SELECT * FROM foo;+---+| n |+---+| 1 |+---+
mysql> CREATE TABLE bar (m INT) SELECT n FROM foo;Query OK, 1 row affected (0.02 sec)Records: 1 Duplicates: 0 Warnings: 0
mysql> SELECT * FROM bar;+------+---+| m | n |+------+---+| NULL | 1 |+------+---+