Database design i_-_1_dl300
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This document discusses database application programming interfaces (APIs). It describes textual and graphical interfaces as well as call-level and embedded SQL interfaces. It provides details on vendor-specific call-level interfaces, the SQL Call Level Interface standard, and APIs like ODBC and JDBC. Examples are given showing how to connect to a database and execute queries using JDBC. Prepared statements in JDBC are also demonstrated. Finally, embedded SQL is briefly explained.
![UU - IT - UDBL 9
JDBC example
import java.sql.*;
public class JDBCExample {
public static void main(String args[]) {
String url = "jdbc:mySubprotocol:myDataSource";
Connection con;
String query = "SELECT NAME FROM EMPLOYEE WHERE INCOME > 10000";
Statement stmt;
try {
Class.forName("myDriver.ClassName");
}catch(java.lang.ClassNotFoundException e) {
System.err.print("ClassNotFoundException: ");
System.err.println(e.getMessage());
}
try {
con = DriverManager.getConnection(url, "myLogin", "myPassword");
stmt = con.createStatement();
ResultSet rs = stmt.executeQuery(query);
while (rs.next()) {
String s = rs.getString(”NAME");
System.out.println(s);
}
rs.close();
stmt.close();
con.close();
}catch(SQLException ex) {
System.err.print("SQLException: ");
System.err.println(ex.getMessage()); }}}
Kjell Orsborn 8/12/09](https://image.slidesharecdn.com/databasedesigni-1dl300-121109001422-phpapp01/85/Database-design-i_-_1_dl300-9-320.jpg)
![UU - IT - UDBL 10
JDBC example (prepared statement)
import java.sql.*;
public class JDBCExample {
public static void main(String args[]) {
String url = "jdbc:mySubprotocol:myDataSource";
Connection con;
String query = "SELECT NAME FROM EMPLOYEE WHERE INCOME > ?;
Int incomeLimit;
PreparedStatement stmt;
try {
Class.forName("myDriver.ClassName");
}catch(java.lang.ClassNotFoundException e) {
System.err.print("ClassNotFoundException: ");
System.err.println(e.getMessage());
}
try {
con = DriverManager.getConnection(url, "myLogin", "myPassword");
stmt = con.prepareStatement(query);
while(....) {
.... // Code to read lower income limit into incomeLimit
stmt.setInt(1,incomeLimit);
ResultSet rs = stmt.executeQuery();
while (rs.next()) {
System.out.println(rs.getString(”NAME"));
}}
rs.close();
stmt.close();
con.close();
}catch(SQLException ex) {
System.err.print("SQLException: ");
System.err.println(ex.getMessage()); }}}
Kjell Orsborn 8/12/09](https://image.slidesharecdn.com/databasedesigni-1dl300-121109001422-phpapp01/85/Database-design-i_-_1_dl300-10-320.jpg)
Database design i_-_1_dl300
- 1. UU - IT - UDBL 1 DATABASE DESIGN I - 1DL300 Summer 2009 An introductury course on database systems http://user.it.uu.se/~udbl/dbt-sommar09/ alt. http://www.it.uu.se/edu/course/homepage/dbastekn/st09/ Kjell Orsborn Uppsala Database Laboratory Department of Information Technology, Uppsala University, Uppsala, Sweden Kjell Orsborn 8/12/09
- 2. UU - IT - UDBL 2 Database API:s (Elmasri/Navathe ch. 9) (Padron-McCarthy/Risch ch 20) Kjell Orsborn Department of Information Technology Uppsala University, Uppsala, Sweden Kjell Orsborn 8/12/09
- 3. UU - IT - UDBL 3 Database user interfaces • Textual interfaces – Such as BSQL for Mimer • Graphical interfaces – Most well-known is QBE (Query-By-Example) originally developed by IBM. MS Access uses a QBE variant. • SQL application programming interfaces – Requires management of sessions, sql statements and some control of query optimization. – Call-level interfaces – Embedded SQL Kjell Orsborn 8/12/09
- 4. UU - IT - UDBL 4 Call-Level Interfaces • Vendor-specific call-level interfaces – An SQL API usually for one or several host languages like C, C++, Java, Fortan, COBOL etc. – Support to manage sessions, SQL statements and data conversions • SQL Call Level Interface (CLI), – The Call Level Interface (CLI) is a standard SQL API created by The Open Group. The API is defined for C and COBOL only. ISBN: 1-85912-081-4, X/Open Document Number: C451, 1995. • SQL/CLI – Call-Level Interface (SQL/CLI) is an implementation-independent CLI to access SQL databases. SQL/CLI is an ISO standard ISO/IEC 9075-3:1995 Information technology -- Database languages -- SQL -- Part 3: Call-Level Interface (SQL/CLI). The current SQL/CLI effort is adding support for SQL:1999. • ODBC – (Microsoft) Open Database Connectivity is a standard SQL API. ODBC is based on the Call Level Interface (CLI) specifications from SQL, X/Open (now part of The Open Group), and the ISO/IEC. ODBC was created by the SQL Access Group and released Sept, 1992. • JDBC - Java Database Connectivity – JDBC is an SQL API for Java (to be strictly correct, JDBC is not an acronym). Kjell Orsborn 8/12/09
- 5. UU - IT - UDBL 5 The ODBC architecture • ODBC API is independent of any one programming language, database system or operating system. Kjell Orsborn 8/12/09
- 6. UU - IT - UDBL 6 The JDBC architecture • JDBC API is independent of (relational) DBMS and operating system Kjell Orsborn 8/12/09
- 7. UU - IT - UDBL 7 Alt. JDBC architecture (JDBC-ODBC bridge) • Makes ODBC accessible from JDBC such that no special JDBC drivers are required. Kjell Orsborn 8/12/09
- 8. UU - IT - UDBL 8 Programming with SQL CLI interfaces JDBC example • The JDBC API (Application Program Interface) is a set of Java interfaces that allow database applications to: – open connections to a database, – execute SQL statements, and – process the results. • These include: – java.sql.DriverManager, which loads the specific drivers and supports creating new database connections – java.sql.Connection, which represents a connection to a specific database – java.sql.Statement, which allows the application to execute a SQL statement – java.sql.PreparedStatement, which represents a pre-compiled SQL statement – java.sql.ResultSet, controls access to rows resulting from executing a statement Kjell Orsborn 8/12/09
- 9. UU - IT - UDBL 9 JDBC example import java.sql.*; public class JDBCExample { public static void main(String args[]) { String url = "jdbc:mySubprotocol:myDataSource"; Connection con; String query = "SELECT NAME FROM EMPLOYEE WHERE INCOME > 10000"; Statement stmt; try { Class.forName("myDriver.ClassName"); }catch(java.lang.ClassNotFoundException e) { System.err.print("ClassNotFoundException: "); System.err.println(e.getMessage()); } try { con = DriverManager.getConnection(url, "myLogin", "myPassword"); stmt = con.createStatement(); ResultSet rs = stmt.executeQuery(query); while (rs.next()) { String s = rs.getString(”NAME"); System.out.println(s); } rs.close(); stmt.close(); con.close(); }catch(SQLException ex) { System.err.print("SQLException: "); System.err.println(ex.getMessage()); }}} Kjell Orsborn 8/12/09
- 10. UU - IT - UDBL 10 JDBC example (prepared statement) import java.sql.*; public class JDBCExample { public static void main(String args[]) { String url = "jdbc:mySubprotocol:myDataSource"; Connection con; String query = "SELECT NAME FROM EMPLOYEE WHERE INCOME > ?; Int incomeLimit; PreparedStatement stmt; try { Class.forName("myDriver.ClassName"); }catch(java.lang.ClassNotFoundException e) { System.err.print("ClassNotFoundException: "); System.err.println(e.getMessage()); } try { con = DriverManager.getConnection(url, "myLogin", "myPassword"); stmt = con.prepareStatement(query); while(....) { .... // Code to read lower income limit into incomeLimit stmt.setInt(1,incomeLimit); ResultSet rs = stmt.executeQuery(); while (rs.next()) { System.out.println(rs.getString(”NAME")); }} rs.close(); stmt.close(); con.close(); }catch(SQLException ex) { System.err.print("SQLException: "); System.err.println(ex.getMessage()); }}} Kjell Orsborn 8/12/09
- 11. UU - IT - UDBL 11 Embedded SQL • Host language include embedded and specially marked SQL statements. • Embedded statements are extracted by preprocessor, translated and replaced by database calls, precompiled (prepared) and stored on server. • The preprocessed application is then compiled normally • Supports dynamic recompilation • Reduces optimization cost and can be somewhat simpler than CLI programming. Kjell Orsborn 8/12/09