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JDBC. by Jon Pearce. DBase Concepts. Terms. Table Row/Entity Column/Field/Attribute Key/Primary Key/Foreign Key. Person OID FIRST LAST ADDRESS PHONE. Address OID STREET CITY STATE. Phone OID AREA NUMBER. Entity-Relation Diagram. 1. 1. *. *. Person Table. Address Table.

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JDBC

by Jon Pearce



Terms
Terms

  • Table

  • Row/Entity

  • Column/Field/Attribute

  • Key/Primary Key/Foreign Key


Entity relation diagram

Person

OID

FIRST

LAST

ADDRESS

PHONE

Address

OID

STREET

CITY

STATE

Phone

OID

AREA

NUMBER

Entity-Relation Diagram

1

1

*

*





SQL

  • SELECT-FROM-WHERE

  • INSERT INTO

  • UPDATE

  • DELETE-FROM


Select
Select

SELECT field1, field2, field3 ... FROM table1, table2, table3 ... WHERE condition


Projection
Projection

SELECT first, last FROM Person


Selection
Selection

SELECT * FROM Person WHERE last LIKE 'D%'


Join

SELECT * FROM Person, Address WHERE Person.Address = Address.OID


Insert
Insert

INSERT INTO table (field, field, ...) VALUES (value, value, ...)


Update
Update

UPDATE table SET field = value, ... WHERE condition


Delete
Delete

DELETE FROM table WHERE condition




Jdbc driver types
JDBC Driver Types

  • JDBC-to-ODBC Bridge

  • Native API partly Java drivers

  • JDBC-Net pure Java drivers

  • Native-protocol pure Java drivers





Sql browser declaration
SQL Browser Declaration

public class SQLBrowser extends Console { protected String driverName; protected String dbaseName; protected Connection connection; protected Statement statement; protected ResultSet result; public SQLBrowser(String db) throws SQLException, ClassNotFoundException {...} public void finalize() throws SQLException {...} private String toString (ResultSet rs) throws SQLException {...} public String execute(String sql) throws AppError {...}}


Connecting
Connecting

public SQLBrowser(String db) throws SQLException, ClassNotFoundException { Class.forName(driverName); dbaseName = "jdbc:cloudscape:rmi:" + db; connection = DriverManager.getConnection(dbaseName); statement = connection.createStatement(); meta = connection.getMetaData();}


Executing a query
Executing a Query

public String execute(String sql) throws AppError { String answer = "???"; try { result = statement.executeQuery(sql); answer = toString(result); } catch (SQLException e) { } return answer;}


Processing a result set
Processing a Result Set

private String toString (ResultSet rs) throws SQLException { StringBuffer results = new StringBuffer(); ResultSetMetaData metaData = rs.getMetaData(); int numCols = metaData.getColumnCount(); for(int i = 1; i <= numCols; i++) { // get column names results.append(metaData.getColumnName(i) + "\t"); } results.append("\n"); while(rs.next()) { // get next row for(int i = 1; i <= numCols; i++) { results.append(rs.getObject(i) + "\t"); } results.append("\n"); } return results.toString();}


Closing the connection
Closing the Connection

public void finalize() throws SQLException { statement.close(); connection.close();}


Dbase dao
DBase DAO

public class DBaseDAO { protected String driver; protected String url; // "protocol:subprotocol:dbase" protected Connection connection; public DBaseDAO(String d, String u) throws DAOException {...} protected void connect() throws Exception {...} public void close() throws DAOException {...} protected void finalize() {...}}


Connecting1
Connecting

protected void connect() throws Exception { Class.forName( driver ); connection = DriverManager.getConnection( url ); connection.setAutoCommit( false );}




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