1. Riyadh Philanthropic Society For Science Prince Sultan College For Woman Dept. of Computer & Information Sciences CS 340 Introduction to Database Systems (Chapter 9: Introduction to SQL Programming Techniques)

2. Chapter 9: Introduction to SQL Programming Techniques1 Outline Database Programming Approaches to Database Programming

3. Chapter 9: Introduction to SQL Programming Techniques Database Programming Objective: to access a database from an application program (as opposed to interactive interfaces). Why? An interactive interface is convenient but not sufficient. (e.g. SQLPLUS) A majority of database operations are made through application programs (nowadays through web applications). 2

4. Chapter 9: Introduction to SQL Programming Techniques Approaches to Database Programming Embedding Database Commands: Most SQL statements can be embedded in a general-purpose host programming language such as C and Java. An embedded SQL statement is distinguished from the host language statements by EXEC SQL and a matching END-EXEC (or semicolon). A precompiler (preprocessor) first scans the source program code to identify database statements and extract them for processing by the DBMS. They are replaced in the program by function calls to the DBMS- generated code. 3

5. Chapter 9: Introduction to SQL Programming Techniques Approaches to Database Programming Using a Library of Database Functions: A library of functions is made available to the host programming language for database calls. The actual database query and update commands, and any other necessary information, are included as parameters in the function calls. This approach provides what is known as an API for accessing a database from application programs. 4

6. Chapter 9: Introduction to SQL Programming Techniques Approaches to Database Programming Designing a Brand-New Language: A database programming language s designed from scratch to be compatible with the database model and query language. Minimizes impedance mismatch. E.g. ORACLE’s PL/SQL. 5

7. Chapter 9: Introduction to SQL Programming Techniques A C Program Segment with Embedded SQL loop = 1; while (loop) { prompt (”Enter a Social Security Number: ", ssn); EXEC SQL select FNAME, MINIT, LNAME, ADDRESS, SALARY into :fname, :minit, :lname, :address, :salary from EMPLOYEE where SSN=:ssn; if (SQLCODE == 0) printf (fname, minit, lname, address, salary) else printf("Social Security Number does not exist: ”, ssn); prompt("More Social Security Numbers (1 = Yes, 0 = No): ”, loop); } 6

8. Chapter 9: Introduction to SQL Programming Techniques Embedded Versus Dynamic SQL Embedded SQL: including hard-coded SQL statements in a program written in another language such as C or Java. Dynamic SQL: ability for an application program to generate SQL code on the fly, as the application is running. 7

9. Chapter 9: Introduction to SQL Programming Techniques Database Programming with Function Calls The use of function calls is a more dynamic approach for database programming than embedded SQL. One dynamic database technique is the dynamic SQL. Another technique uses a library of functions (API) to access the database. Two function call interfaces are: SQL/CLI & JDBC. 8