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JDBC
Java Database Connection
Helia / Martti Laiho, 1998-2000
Notes on JDBC - Java Database Connection
Class Library: java.sql.*
Literature/sources:
• SunSoft: http://java.sun.com/products/jdbc JDBC Specification
• jdk1.3/docs/guide/jdbc/
JDBC Guide: Getting Started
• Seth White & al: JDBCTM API Tutorial and Reference, 2nd ed
• Horstmann & Cornell: Core JAVA Volume II Chapter 4
• Orfali & Harkey: Client/Server Programming with JAVA and CORBA
• Siple: The Complete Guide to JAVA Database Programming, McGraw-Hill
• SOLID JDBC: sj23win.zip SOLID JDBC Driver Programmer’s Guide
• Melton & Eisenberg: Understanding SQL and Java Together
Helia / Martti Laiho, 1998-2000
JDBC 1.0 API
•
•
•
•
Designed by JavaSoft
based on ISO SQL/CLI and Microsoft ODBC API
provided in java.sql package
4 types of JDBC Driver implementation
Helia / Martti Laiho, 1998-2000
Types of JDBC Implementations
- Melton & Eisenberg
Type 1
Type 2
Type 3
Type 4
Java appl
Java appl
Java appl
Java appl
JDBC-ODBC
bridge
JDBC
driver
JDBC
driver
JDBC
driver
ODBC
driver
Native
db-library
Proprietary
protocol
DBMS
Proprietary
protocol
DBMS
- Oracle JDBC/OCI
DBMS- independent
protocol
DBMS- specific
protocol
JDBC server
gateway
DBMS
DBMS
- Oracle Thin JDBC
- Sybase jConnect
- Solid
Helia / Martti Laiho, 1998-2000
SQL and Java data types
SQL data type:
Java data type:
INT[EGER]
SMALLINT
NUMERIC (m, n)
DECIMAL (m, n)
DEC (m, n)
FLOAT (n)
REAL
DOUBLE
CHAR[ACTER] (n)
VARCHAR (n)
DATE
TIME
TIMESTAMP
int
short
java.sql.BigDecimal
java.sql.BigDecimal
java.sql.BigDecimal
double
float
double
String
String
java.sql.Date
java.sql.Time
java.sql.Timestamp
Helia / Martti Laiho, 1998-2000
Java.sql - Interfaces / Methods
DatabaseMetaData
DataSource
getTables(…)
…
getConnection
(url, user, psw)
DriverManager
Class
getConnection
(url, user, psw)
Driver
Connection
Statement
getMetaData()
setAutoCommit(b)
setTransaction
Isolation(level)
createStatement()
prepareStatement(sql)
prepareCall(sql)
commit()
rollback()
close()
setCursorName(s)
executeQuery(sql)
executeUpdate(sql)
cancel()
close()
...
PreparedStatement
…
setXxxx(n, hvar)
clearParameters()
SQLException
CallableStatement
getSQLState()
getErrorCode()
getNextExcetion()
registerOutputParameter
execute()
...
ResultSet
getMetaData()
findColumn(name)
next()
getInt(col)
getShort(col)
getNumeric(col)
getDouble(col)
getFloat(col)
getString(col)
getDate(col)
getTime(col)
getTimestamp(col)
wasNull()
setText(s)
append(s)
close()
ResultSetMetaData
getColumnCount()
getColumnName(i)
getColumnLabel(i)
getColumnDisplaySize(i)
Helia / Martti Laiho, 1998-2000
SQL Query
String s;
float n;
...
String query = "SELECT COF_NAME, PRICE FROM COFFEES";
ResultSet rs = stmt.executeQuery(query);
while (rs.next()) {
s = rs.getString("COF_NAME");
rs.next()
COF_NAME PRICE
n = rs.getFloat("PRICE");
System.out.println(s + " " + n);
}
rs.getString()
rs.close;
s
n
rs.getFloat()
Helia / Martti Laiho, 1998-2000
SQLQuery Sequence Diagram
Client
adapted from Orfali & Harkey
DriverManager
getConnection
Connection
createStatement
Statement
executeQuery
ResultSet
next
getString
getInt
...
{ [ Until next returns false ] }
close
close
close
Helia / Martti Laiho, 1998-2000
Invoking a Stored Procedure
Client
adapted from Orfali & Harkey
DriverManager
getConnection
Connection
prepareCall
Callable
Statement
registerOutputParameter
...
execute
parameters marked in the
procedures call by ? placeholders
are identified by the corresponding
order numbers 1, 2, .. of the
placeholders
getString
getInt
...
close
close
Helia / Martti Laiho, 1998-2000
JDBC Escape Syntax
call
?=call
d
escape
fn
oj
t
ts
{call proc (arg1, …) }
{?= call proc (arg1, …) }
{d ‘yyyy-mm-dd’}
{escape ‘%’}
{fn function (arg1, …) }
{oj outer-join }
{t ‘hh:mm:ss’}
{ts ‘yyyy-mm-dd hh:mm:ss.fffff’}
Helia / Martti Laiho, 1998-2000
Transactions
Default: AutoCommit
Isolation Levels:
0
TRANSACTION_NONE
1
TRANSACTION_READ_UNCOMMITTED
2
TRANSACTION_READ_COMMITTED
3
TRANSACTION_REAPEATABLE_READ
4
TRANSACTION_SERIALIZABLE
Methods:
con.setAutoCommit(false);
level = con.getTransactionIsolation();
con.setTransactionIsolation(level);
con.commit();
con.rollback();
Helia / Martti Laiho, 1998-2000
Exception handling
- adapted from Core JAVA Vol II ch 4 p 206
try {
jdbc method call ...
}
catch (SQLException ex) {
System.out.println (”\nSQLException:");
while (ex != null) {
System.out.println (”SQLState: "+ex.getSQLState());
System.out.println (”Message: "+ ex.getMessage());
System.out.println (”Vendor: "+ ex.getErrorCode());
ex = ex.getNextException();
}
}
catch (java.lang.Exception ex) {
System.out.println("Exception: " + ex);
ex.printStackTrace ();
}
Helia / Martti Laiho, 1998-2000
JDBC 2.0 API
• JDBC 2.0 Core API (java.sql)
–
–
–
–
Scrollable ResultSet
Updating by ResultSet
Batch Updates
New SQL-99 datatypes
• JDBC 2.0 Standard Extension API (javax.sql)
Helia / Martti Laiho, 1998-2000
Scrollable ResultSet
• Resultset types
– TYPE_FORWARD_ONLY
– TYPE_SCROLL_INSENSITIVE
– TYPE_SCROLL_SENSITIVE
(~JDBC 1.0)
• Methods
–
–
–
–
–
–
–
–
–
–
–
beforeFirst()
(initially)
first()
next()
(JDBC 1.0)
previous()
last()
afterLast()
absolute (n | -n)
relative (n | -n)
getRow()
isFirst() , isLast() , isBeforeFirst() , isAfterLast()
moveToInsertRow(), moveToCurrentRow()
Helia / Martti Laiho, 1998-2000
Updatable ResultSet
• Updatable
– CONCUR_READ_ONLY (~JDBC 1.0)
– CONCUR_UPDATABLE
• Methods
– updateXXX(column, value)
– …
– updateRow() or cancelRowUpdates()
Helia / Martti Laiho, 1998-2000
Inserting a new row
• InsertRow processing:
ResultSet:
– moveToInsertRow()
– updateXXX( , ) ….
– insertRow()
“Current row”
– moveToCurrentRow()
moveToCurrentRow()
updateable
row
moveToInsertRow()
InsertRow()
“InsertRow buffer”
Helia / Martti Laiho, 1998-2000
Deleting a Row
• Positioning in the ResultSet and deleting:
– <move method>
– deleteRow()
• Note:
– drivers handle deletions differently
Helia / Martti Laiho, 1998-2000
Refreshing the row
• Applies only to Cursor type:
– TYPE_SCROLL_SENSITIVE
• method
– refreshRow()
Helia / Martti Laiho, 1998-2000
Batch Updates
• Methods
– addBatch(“….”)
– …
– executeBatch();
• BatchUpdateException
Helia / Martti Laiho, 1998-2000
SQL-1999 Datatypes
• BLOB - binary large objects
• CLOB - character large objects
• SQL Array - of any SQL scalar datatype
• SQL structured type - User Defined Type UDT
• SQL REF - identifier
Helia / Martti Laiho, 1998-2000
JDBC 2.0 Standard Extension API
• JDBC 2.0 Standard Extension API
i.e. Optional Package API
– in javax.sql
–
–
–
–
JavaBeans: Rowsets
JNDI for naming and directory interface
Connection Pooling
Distributed Transactions: 2PC by Java Transaction API
(JTA)
Helia / Martti Laiho, 1998-2000