Relational Algebra and Calculus Introduction to SQL University
Relational Algebra and Calculus: Introduction to SQL University of California, Berkeley School of Information Management and Systems SIMS 257: Database Management IS 257 - Fall 2002. 10 - SLIDE 1
Lecture Outline • Review • • – Design to Relational Implementation Relational Operations Relational Algebra Relational Calculus Introduction to SQL IS 257 - Fall 2002. 10 - SLIDE 2
Lecture Outline • Review • • – Design to Relational Implementation Relational Operations Relational Algebra Relational Calculus Introduction to SQL IS 257 - Fall 2002. 10 - SLIDE 3
Database Design Process Application 1 External Model Application 2 Application 3 Application 4 External Model Application 1 Conceptual requirements Application 2 Conceptual requirements Application 3 Conceptual requirements Conceptual Model Logical Model Internal Model Application 4 Conceptual requirements IS 257 - Fall 2002. 10 - SLIDE 4
Cookie ER Diagram pubid accno BIBFILE CALLFILE accno AU_BIB LIBFILE libid AU ID PUBFILE INDXFILE pubid SUBFILE AUTHORS accno AU_ID Author IS 257 - Fall 2002 subcode Note: diagram contains only attributes used for linking 2002. 10 - SLIDE 5
What Problems? • What sorts of problems and missing features arise given the previous ER diagram? IS 257 - Fall 2002. 10 - SLIDE 6
Problems Identified • • Subtitles, parallel titles? Edition information Series information lending status material type designation Genre, class information Better codes (ISBN? ) Missing information (ISBN) IS 257 - Fall 2002 • Authority control for authors • Missing/incomplete data • Data entry problems • Ordering information • Illustrations • Subfield separation (such as last_name, first_name) • Separate personal and corporate authors 2002. 10 - SLIDE 7
Problems (Cont. ) • Location field inconsistent • No notes field • No language field • Zipcode doesn’t support plus-4 • No publisher shipping addresses IS 257 - Fall 2002 • No (indexable) keyword search capability • No support for multivolume works • No support for URLs – to online version – to libraries – to publishers 2002. 10 - SLIDE 8
Original Cookie ER Diagram pubid accno BIBFILE CALLFILE accno AU_BIB LIBFILE libid AU ID PUBFILE INDXFILE pubid SUBFILE AUTHORS accno AU_ID Author IS 257 - Fall 2002 subcode Note: diagram contains only attributes used for linking 2002. 10 - SLIDE 9
Cookie 2: Separate Name Authorities pubid accno BIBFILE CALLFILE accno AUTHBIB LIBFILE libid nameid PUBFILE authtype INDXFILE pubid SUBFILE AUTHFILE accno nameid IS 257 - Fall 2002 subcode name 2002. 10 - SLIDE 10
Cookie 3: Keywords termid accno termid pubid accno BIBFILE TERMS CALLFILE LIBFILE accno AUTHBIB KEYMAP libid nameid PUBFILE authtype INDXFILE pubid SUBFILE AUTHFILE accno nameid IS 257 - Fall 2002 subcode name 2002. 10 - SLIDE 11
ser_title SERIES Cookie 4: Series seriesid termid accno termid seriesid pubid accno BIBFILE TERMS CALLFILE LIBFILE accno AUTHBIB KEYMAP libid nameid PUBFILE authtype INDXFILE pubid SUBFILE AUTHFILE accno nameid IS 257 - Fall 2002 subcode name 2002. 10 - SLIDE 12
ser_title SERIES Cookie 5: Circulation seriesid termid accno termid seriesid pubid accno BIBFILE TERMS CALLFILE LIBFILE accno AUTHBIB KEYMAP libid circid libid nameid PUBFILE authtype pubid PATRON INDXFILE SUBFILE CIRC AUTHFILE accno nameid IS 257 - Fall 2002 name subcode copynumpatronid circid 2002. 10 - SLIDE 13
Logical Model: Mapping to Relations • Take each entity – BIBFILE – LIBFILE – CALLFILE – SUBFILE – PUBFILE – INDXFILE • And make it a table. . . IS 257 - Fall 2002. 10 - SLIDE 14
Lecture Outline • Review • • – Design to Relational Implementation Relational Operations Relational Algebra Relational Calculus Introduction to SQL IS 257 - Fall 2002. 10 - SLIDE 15
Relational Algebra Operations • • Select Project Product Union Intersect Difference Join Divide IS 257 - Fall 2002. 10 - SLIDE 16
Select • Extracts specified tuples (rows) from a specified relation (table). IS 257 - Fall 2002. 10 - SLIDE 17
Project • Extracts specified attributes(columns) from a specified relation. IS 257 - Fall 2002. 10 - SLIDE 18
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) Product a b c IS 257 - Fall 2002 x y a a b b c c x y x y 2002. 10 - SLIDE 19
Union • Builds a relation consisting of all tuples appearing in either or both of two specified relations. IS 257 - Fall 2002. 10 - SLIDE 20
Intersect • Builds a relation consisting of all tuples appearing in both of two specified relations IS 257 - Fall 2002. 10 - SLIDE 21
Difference • Builds a relation consisting of all tuples appearing in first relation but not the second. IS 257 - Fall 2002. 10 - SLIDE 22
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. ) A 1 B 1 A 2 B 1 A 3 B 2 IS 257 - Fall 2002 B 1 C 1 B 2 C 2 B 3 C 3 (Natural or Inner) Join A 1 B 1 C 1 A 2 B 1 C 1 A 3 B 2 C 2 2002. 10 - SLIDE 23
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. A 1 A 2 A 3 A 4 IS 257 - Fall 2002 B 1 B 2 B 7 B 1 C 1 B 2 C 2 B 3 C 3 Outer Join A 1 B 1 C 1 A 2 B 1 C 1 A 3 B 2 C 2 A 4 * * 2002. 10 - SLIDE 24
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 a a b c IS 257 - Fall 2002 x y z x y Divide a x y 2002. 10 - SLIDE 25
ER Diagram: Acme Widget Co. Wage Emp# ISA Hourly Sales Cust# Customer Employee Sales-Rep Writes Orders Invoice# Rep# Cust# IS 257 - Fall 2002 Part# Invoice# Quantity Contains Line-Item Contains Part# Count Price 2002. 10 - SLIDE 26
Employee IS 257 - Fall 2002. 10 - SLIDE 27
Part IS 257 - Fall 2002. 10 - SLIDE 28
Sales-Rep Hourly IS 257 - Fall 2002. 10 - SLIDE 29
Customer IS 257 - Fall 2002. 10 - SLIDE 30
Invoice IS 257 - Fall 2002. 10 - SLIDE 31
Line-Item IS 257 - Fall 2002. 10 - SLIDE 32
Join Items IS 257 - Fall 2002. 10 - SLIDE 33
Lecture Outline • Review • • – Design to Relational Implementation Relational Operations Relational Algebra Relational Calculus Introduction to SQL IS 257 - Fall 2002. 10 - SLIDE 34
Relational Algebra • What is the name of the customer who ordered Large Red Widgets? – Select “large Red Widgets” from Part as temp 1 – Join temp 1 with Line-item on Part # as temp 2 – Join temp 2 with Invoice on Invoice # as temp 3 – Join temp 3 with customer on cust # as temp 4 – Project Name from temp 4 IS 257 - Fall 2002. 10 - SLIDE 35
Lecture Outline • Review • • – Design to Relational Implementation Relational Operations Relational Algebra Relational Calculus Introduction to SQL IS 257 - Fall 2002. 10 - SLIDE 36
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 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. IS 257 - Fall 2002. 10 - SLIDE 37
Lecture Outline • Review • • – Design to Relational Implementation Relational Operations Relational Algebra Relational Calculus Introduction to SQL IS 257 - Fall 2002. 10 - SLIDE 38
SQL • Structured Query Language • Database Definition and Querying • Basic language is standardized across relational DBMSs. Each system may have proprietary extensions to standard. • Relational Calculus combines Select, Project and Join operations in a single command. SELECT. IS 257 - Fall 2002. 10 - SLIDE 39
SQL - History • Structured Query Language • SEQUEL from IBM San Jose • ANSI 1992 Standard is the version used by most DBMS today (SQL 92) • Basic language is standardized across relational DBMSs. Each system may have proprietary extensions to standard. IS 257 - Fall 2002. 10 - SLIDE 40
SQL 99 • In 1999, SQL 99 – also known as SQL 3 – 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 SQL 92 IS 257 - Fall 2002. 10 - SLIDE 41
SQL 99 • 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. IS 257 - Fall 2002. 10 - SLIDE 42
SQL 99 • 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. IS 257 - Fall 2002. 10 - SLIDE 43
SQL 99 • 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. IS 257 - Fall 2002. 10 - SLIDE 44
SQL 99 Data Types NEW IN SQL 99 SQL Data Types Predefined Types Ref Types Numeric String Bit Exact User-Defined Types Arrays Character Approximate Date. Time Blob Fixed ROW Data Struct Interval Boolean Date Time Fixed Varying Timestamp CLOB IS 257 - Fall 2002. 10 - SLIDE 45
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 IS 257 - Fall 2002. 10 - SLIDE 46
SELECT • Syntax: – SELECT [DISTINCT] attr 1, attr 2, …, attr 3 FROM rel 1 r 1, rel 2 r 2, … rel 3 r 3 WHERE condition 1 {AND | OR} condition 2 ORDER BY attr 1 [DESC], attr 3 [DESC] IS 257 - Fall 2002. 10 - SLIDE 47
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. . . IS 257 - Fall 2002. 10 - SLIDE 48
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 (“opt 1”, “opt 2”, …, ”optn”) • BETWEEN val 1 AND val 2 • IS NULL IS 257 - Fall 2002. 10 - SLIDE 49
Relational Algebra Selection using SELECT • Syntax: – SELECT * WHERE condition 1 {AND | OR} condition 2; IS 257 - Fall 2002. 10 - SLIDE 50
Relational Algebra Projection using SELECT • Syntax: – SELECT [DISTINCT] attr 1, attr 2, …, attr 3 FROM rel 1 r 1, rel 2 r 2, … rel 3 r 3; IS 257 - Fall 2002. 10 - SLIDE 51
Relational Algebra Join using SELECT • Syntax: – SELECT * FROM rel 1 r 1, rel 2 r 2 WHERE r 1. linkattr = r 2. linkattr ; IS 257 - Fall 2002. 10 - SLIDE 52
Sorting • SELECT BIOLIFE. [Common Name], BIOLIFE. [Length (cm)] FROM BIOLIFE ORDER BY BIOLIFE. [Length (cm)] DESC; Note: the square brackets are not part of the standard, But are used in Access for names with embedded blanks IS 257 - Fall 2002. 10 - SLIDE 53
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. IS 257 - Fall 2002. 10 - SLIDE 54
Aggregate Functions • • • Count Avg SUM MAX MIN Others may be available in different systems IS 257 - Fall 2002. 10 - SLIDE 55
Using Aggregate functions • SELECT attr 1, Sum(attr 2) AS name FROM tab 1, tab 2. . . GROUP BY attr 1, attr 3 HAVING condition; IS 257 - Fall 2002. 10 - SLIDE 56
Using an Aggregate Function • SELECT DIVECUST. Name, Sum([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")); IS 257 - Fall 2002. 10 - SLIDE 57
GROUP BY • SELECT DEST. [Destination Name], Count(*) AS Expr 1 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 destination IS 257 - Fall 2002. 10 - SLIDE 58
Create Table • CREATE TABLE table-name (attr 1 attrtype PRIMARYKEY, attr 2 attr-type, …, attr. N attr-type); • Adds a new table with the specified attributes (and types) to the database. IS 257 - Fall 2002. 10 - SLIDE 59
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) IS 257 - Fall 2002. 10 - SLIDE 60
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. 402823 E 38 to – 1. 401298 E– 45 for negative values and from 1. 401298 E– 45 to 3. 402823 E 38 for positive values. 4 bytes • Double – Stores numbers from – 1. 79769313486231 E 308 to – 4. 94065645841247 E– 324 for negative values and from 1. 79769313486231 E 308 to 4. 94065645841247 E– 324 for positive values. 15 8 bytes • Replication ID – Globally unique identifier (GUID) IS 257 - Fall 2002 N/A 16 bytes 2002. 10 - SLIDE 61
Oracle Data Types • • CHAR (size) -- max 2000 VARCHAR 2(size) -- up to 4000 DATE DECIMAL, FLOAT, INTEGER(s), SMALLINT, 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 IS 257 - Fall 2002. 10 - SLIDE 62
Creating a new table from existing tables • Syntax: – SELECT [DISTINCT] attr 1, attr 2, …, attr 3 INTO newtablename FROM rel 1 r 1, rel 2 r 2, … rel 3 r 3 WHERE condition 1 {AND | OR} condition 2 ORDER BY attr 1 [DESC], attr 3 [DESC] IS 257 - Fall 2002. 10 - SLIDE 63
Alter Table • ALTER TABLE table-name ADD COLUMN attr 1 attr-type; • … DROP COLUMN attr 1; • Adds a new column to an existing database table. IS 257 - Fall 2002. 10 - SLIDE 64
INSERT • INSERT INTO table-name (attr 1, attr 4, attr 5, …, attr. K) VALUES (“val 1”, val 4, val 5, …, “val. K”); • Adds a new row(s) to a table. • INSERT INTO table-name (attr 1, attr 4, attr 5, …, attr. K) VALUES SELECT. . . IS 257 - Fall 2002. 10 - SLIDE 65
DELETE • DELETE FROM table-name WHERE <where clause>; • Removes rows from a table. IS 257 - Fall 2002. 10 - SLIDE 66
UPDATE • UPDATE tablename SET attr 1=newval, attr 2 = newval 2 WHERE <where clause>; • changes values in existing rows in a table (those that match the WHERE clause). IS 257 - Fall 2002. 10 - SLIDE 67
DROP Table • DROP TABLE tablename; • Removes a table from the database. IS 257 - Fall 2002. 10 - SLIDE 68
CREATE INDEX • CREATE [ UNIQUE ] INDEX indexname ON tablename (attr 1 [ASC|DESC][, attr 2 [ASC|DESC], . . . ]) [WITH { PRIMARY | DISALLOW NULL | IGNORE NULL }] IS 257 - Fall 2002. 10 - SLIDE 69
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