Java Programming/Database Programming
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Java uses JDBC, an API that defines how a client may access a database. Its drivers may be installed first. [1] [2]
Connecting to Microsoft Access databases
[edit | edit source ]The following is used to open an ODBC connection to an Access database. Note that the username (and password, if applicable) are given in the DSN rather than the getConnection call. This is a MS Windows-only example, due to the requirement for the Microsoft Access Driver.
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); Stringpath="C:/example.mdb"; Stringdsn="jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)};DBQ="+path+";UID=admin"; accessConn=DriverManager.getConnection(dsn,"","");
Connecting to MySQL
[edit | edit source ]try{ Class.forName("com.mysql.jdbc.Driver"); Connectionconn=DriverManager.getConnection("jdbc:mysql://localhost/MySite?user=MyAccount&password=MyPassword"); conn.close(); }catch(SQLExceptione){e.printStackTrace();}
Connecting to Oracle Database
[edit | edit source ]This script returns the database size:
importjava.sql.*; importjava.io.*; importoracle.jdbc.*; importoracle.sql.*; publicclass OracleDatabase{ publicstaticvoidmain(String[]args){ try{ DriverManager.registerDriver(neworacle.jdbc.OracleDriver()); Connectionconn=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:MyDatabase","MyAccount","MyPassword"); conn.setAutoCommit(true); Stringsql="SELECT sum(bytes) from dba_segments;"; Statementstmt=conn.createStatement(); stmt.execute(sql); stmt.close(); conn.close(); }catch(SQLExceptione){e.printStackTrace();} } }
Connecting to PostgreSQL
[edit | edit source ]try{ Class.forName("org.postgresql.Driver"); Connectionconn=DriverManager.getConnection("jdbc:postgresql:MyDatabase","MyAccount","MyPassword"); conn.close(); }catch(SQLExceptione){e.printStackTrace();}
Known errors
[edit | edit source ]package oracle.jdbc does not exist
[edit | edit source ]If you have Oracle Database on your PC, just add to the classpath its following files[3] :
- C:\oracle12\app\oracle\product12円.1.0\dbhome_1\jdbc\lib\ojdbc7.jar
- C:\oracle12\app\oracle\product12円.1.0\dbhome_1\sqlj\lib\runtime12.jar
Otherwise, ojdbc7.jar can be downloaded from http://www.oracle.com/technetwork/database/features/jdbc/jdbc-drivers-12c-download-1958347.html, and add it to the compilation. Eg:
javac MyClass.java -classpath ojdbc7.jar
ORA-28009: connection as SYS should be as SYSDBA or SYSOPER
[edit | edit source ]Just add " as sysdba" after your Oracle account name, eg:
Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:MyDatabase", "MyAccount as sysdba",