1. 1 CS 430 Database Theory Winter 2005 Lecture 10: Introduction to SQL

2. 2 SQL History SQL = Structured Query Language History  Initially defined by IBM Almaden Research Labs for System R (an experimental relational database)  Database language for IBM’s DB2 RDBMS Standards  Standardized by ANSI (American National Standards Institute) and ISO (International Standards Organization)  Many Versions and Components

3. 3 SQL1 or SQL-86 SQL-86 was a subset of IBM’s SQL Included basic Data Manipulation Language (DML) Did not include any Data Definition Language (DDL) Language Bindings: COBOL, FORTRAN, Pascal, PL/1 “Least Common Denominator”

4. 4 SQL-89 Superset of SQL-86 Added basic DDL  CREATE and GRANT  No DROP, ALTER, REVOKE  Views Added Ada and C language bindings Included Integrity Enhancements  NOT NULL, FOREIGN KEY, UNIQUE, … Still “Least Common Denominator”

5. 5 SQL2 or SQL-92 Superset of SQL-89, some incompatibilities No longer “Least Common Denominator” Much bigger standard  SQL-89 -- 120 pages  SQL-92 -- 579 pages Not all features available in all products (even today) Defined levels of conformance  Entry, Intermediate, and Full Levels  Entry Level close to SQL-89 with Integrity Enhancements

6. 6 SQL-92 Highlights More data types with operators  Date and Time  Varying length Character Strings Natural Join and Outer Joins Dynamic SQL  SQL constructed dynamically by programs Cascades for Referential Integrity More DML, including ALTER, DROP, REVOKE

7. 7 More SQL-92 Highlights Standard Catalogs Transactions Domains as Macros for constraint checking  Not same as Relational Model domain notion Multiple Character Sets Temporary Tables  Automatically vanish at end of transaction or session

8. 8 SQL3 or SQL-99 Superset of SQL-92, Significantly larger  All the documents add up to over 2000 pages Large Data Types  Binary Large Objects (BLOBs) and Character Large Objects (CLOBs) Recursive Queries Schemas  Can reference multiple schemas simultaneously

9. 9 More SQL-99 Triggers, Stored Procedures  Procedural Language (SQL/Persistent Stored Modules (PSM)) Standard Programming Language API  SQL/Call Level Interface (CLI)  Standardized version of Microsoft’s ODBC Object/Relational features added  User defined types and methods  Structured and composite types

10. 10 More SQL-99 Divided into Foundation and Packages  SQL-99 Foundation includes all of SQL-92 with extensions Package highlights:  PSM  CLI  Basic Object Support  Enhanced Object Support  Multi-Media Full-text, Spatial, Images

11. 11 Some Basic SQL - Data Types Numeric  Integers of various sizes  Float, Double Precision  DECIMAL(i, j) – i digits, j after decimal point Character String  Fixed length (CHAR)  Varying length (VARCHAR) Bit Strings – both Fixed and Varying Boolean Date and Time  Basic Date and Time types  Timestamp  Interval – Time interval

12. 12 Some Basic SQL - Expressions Basic operations  Arithmetic (+, *, …)  Comparison (=, <, …) Numeric Functions, e.g. SIN, … Control Flow Functions - Case, IF, IFNULL String Functions, e.g. CONCAT, TRIM, … Date/Time manipulation Full Text Search, Pattern Matching Aggregation – SUM, AVERAGE, … And more …

13. 13 Some Basic SQL - Data Definition create table EMPLOYEE (IDIntNOT NULL, NameVarchar(30)NOT NULL, DNumInt, SalaryDecimal(11, 2), primary key (ID), foreign key(Dnum) references Dept(DeptNo)); alter table EMPLOYEE alter DNum set default 999 ;

14. 14 Some Basic SQL - Data Manipulation SELECT  Retrieve a table  Like Relational Calculus INSERT  Add one or more rows to a table UPDATE  Modify one or more rows in a table DELETE  Remove one or more rows from a table

15. 15 Some Basic SQL - SELECT select Id, Name from EMPLOYEE where Salary > 1000000; select DNum, DeptName, average(Salary) from EMPLOYEE, DEPT where EMPLOYEE.Dnum = DEPT.DeptNo group by DNum;

16. 16 Some Basic SQL - INSERT insert into EMPLOYEE values(12345, ‘John Smith’, 99, 55000); insert into Dept_Info( DNum, Name, ASal) select DNum, DeptName, average(Salary) from EMPLOYEE, DEPT where EMPLOYEE.Dnum = DEPT.DeptNo group by DNum;

17. 17 Some Basic SQL – UPDATE update EMPLOYEE set Salary = 100000 where ID = 123; update EMPLOYEE set Salary = Salary * 0.05;

18. 18 Some Basic SQL – DELETE delete from EMPLOYEE where ID = 123; delete from EMPLOYEE;