Download Chapter 9: Introduction to SQL Programming Techniques

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)
Outline
• Database Programming
• Approaches to Database Programming
Chapter 9: Introduction to SQL Programming Techniques
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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).
Chapter 9: Introduction to SQL Programming Techniques
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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 DBMSgenerated code.
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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.
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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.
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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);
}
Chapter 9: Introduction to SQL Programming Techniques
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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.
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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.
Chapter 9: Introduction to SQL Programming Techniques
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