JDBC 920x Date/TimeStamp mapping is different from JDBC 8i, 9iR1 (转贴)

Using the JDBC 8i, 9iR1, Oracle's DATE datatype is mapped to the "java.sql.Timestamp" class. However, the new "ojdbc14.jar" driver maps DATE to "java.sql.Date", and "java.sql.Date" only holds a date (without a time), whereas "java.sql.Timestamp" holds both a date and a time.




Subject: JDBC 920x Date/TimeStamp mapping
Type: BULLETIN
Status: UNDER_EDIT
Content Type: TEXT/PLAIN
Creation Date: 29-JUL-2003
Last Revision Date: 04-OCT-2004

PURPOSE
-------
   Clarify the use of oracle.jdbc.V8Compatible property flag
 
SCOPE & APPLICATION
-------------------
JDBC 920x Date/TimeStamp mapping is different from JDBC 8i, 9iR1.
<TITLE FOR MAIN ARTICLE TEXT>
-----------------------------
Summary of  features afftected by oracle.jdbc.V8Compatible.
 
As of 9.2.0.1.0 Oracle realigned its DATE type with the java.sql.Types.DATE type.
Prior to this
java.sql.DATE and  java.sql.TIMESTAMP were mapped to java.sql.Types.TIMESTAMP.
 
This mapping change applies to JDBC default mapping (i.e when getObject() is
used for Date column.
 
example:
select sysdate from dual;
...
while (rset.next ())  {
System.out.println("getObject for sysdate  : " +
rset.getObject(1).getClass().getName());
System.out.println("getDate for sysdate :" +
rset.getDate(1).getClass().getName());
System.out.println("getTimetamp for sysdate :" +
rset.getTimestamp(1).getClass().getName());
}
 
Prior to 9201, this will return
getObject for sysdate  : java.sql.Timestamp      <<<<
getDate for sysdate :java.sql.Date
getTimetamp for sysdate :java.sql.Timestamp
 
As of 9201 onward the following will be returned
 
getObject for sysdate  : java.sql.Date        <<<<<
getDate for sysdate :java.sql.Date            >> no change
getTimetamp for sysdate :java.sql.Timestamp   >> no change
 
 
 
Note: java.sql.Date has no time portion whereas java.sql.Timestamp does.
 
 
With this change in Datatype mapping, some application will fail and/or generate
incorrect results when JDBC driver is upgraded from 8i/ 9iR1 to 920x JBDC driver.
To maintain compatibility and keep applications working after upgrade, a compatibility flag was
Provided.  Developers now have some options:
 
1>
Use oracle.jdbc.V8Compatible flag.
 
JDBC Driver does not detect database version by default.
To change the compatibility flag for handling TIMESTAMP datatypes,
connection property 'oracle.jdbc.V8Compatible' can be set to
'true' and the driver behaves as it behaved in 8i, 901x, 9200
(with respect to TIMESTAMPs).
By default the flag is set to 'false'. In OracleConnection constructor
the driver obtains the server version and set the compatibility flag
Appropriately.
 
java.util.Properties prop = new java.util.Properties ();
prop.put ("oracle.jdbc.V8Compatible", "true");
prop.put ("user", "scott");
prop.put ("password", "tiger");
String url ="jdbc:oracle:thin:@host:port:sid";
Connection conn = DriverManager.getConnection (url,prop);
 
 
 
With JDBC 10.1.0.x, in instead of the connection property, the following system
property can be useed
java -Doracle.jdbc.V8Compatible=true .....
 
 
 
Note: This flag is a client only flag that governs the Timestamp and Date mapping.
It does not affect any Database feature.
 
 
 
2> use set/getDate and set/getTimestamp   when dealing with Date and TimeStamp column datatype accordingly.
9i server  supports both Date and Timestamp column types
 
DATE is mapped to  java.sql.Date and TIMESTAMP is mapped to java.sql.Timestamp
 
I> using setTimestamp
 
PreparedStatement pstmt = conn.prepareStatement(
"SELECT count(*) from  tstable where tscol between ? and ?");
// tscol of type Timetamp (or it can be Date)
 
String s = new String("2003-01-14 10:00:00.000000000");
Timestamp ts1 = Timestamp.valueOf(s);
pstmt.setTimestamp(1, ts1); // Timestamp
 
String s2 = new String("2003-01-16 10:00:00.000000000");
Timestamp ts2 = Timestamp.valueOf(s2);
pstmt.setTimestamp(2, ts2); // Timestamp
...
 
 
II>using setDate
 
PreparedStatement pstmt = conn.prepareStatement(
"SELECT count(*) from  tstable where datecol between ? and ?");
// datecole of type Date
 
/*
pstmt.setDate(1,new java.sql.Date(System.currentTimeMillis()));
pstmt.setDate(2,new java.sql.Date(System.currentTimeMillis()));
*/
 
SimpleDateFormat start_dt_in1 = new SimpleDateFormat("2002-09-18 00:00:00");
SimpleDateFormat start_dt_in2 = new SimpleDateFormat("2003-09-18 00:00:00");
pstmt.setDate(1,start_dt_in1);
pstmt.setDate(2,start_dt_in2);
 
 
 
Summary of  features afftected by oracle.jdbc.V8Compatible.
 
Is backward compatible (with oracle.jdbc.V8Compatible)?

 
 
* Examples:
..
The following will fail   when using JDBC 9iR1, 9iR2 connecting 817 server since the
817 did not support Timestamp
 
 
Connection conn = DriverManager.getConnection(url, "scott",  "tiger");
// Prepare a statement to cleanup the emp table
Statement  stmt = conn.createStatement();
try {
stmt.execute("delete from EMP where EMPNO = 1");
} catch (SQLException e) {
}
try {
stmt.execute("INSERT INTO EMP (EMPNO, ENAME, HIREDATE) VALUES (1, 
'ALI', {ts '2003-04-14 14:19:24.94'})");
} catch (SQLException e) {
e.printStackTrace();
}
 
Error : Exception in thread "main" java.sql.SQLException: ORA-00904: invalid column name
 
Solution you need
1> fix for Bug 2640192 (included in 9204)
2> oracle.jdbc.V8Compatible", "true"
 
 
 
In earlier versions of JDBC drivers  SQL FUNCTION "TS" was mapped to "to_date" .   So, the query
 
select {ts '2002-10-18 18:02:00'} from dual;
was translated by JDBC to,
select TO_DATE ('2002-10-18 18:02:00',  'YYYY-MM-DD HH24:MI:SS') from dual;
 
 
With 9i Timestamp is supported in the database and also by 9203 JDBC Drivers.
So the query
 
select {ts '2002-10-18 18:02:00'} from dual;
 
is now translated  by JDBC to
 
select TO_TIMESTAMP('2002-10-18 18:02:00', 'YYYY-MM-DD HH24:MI:.SS.FF') from dual;
 
 
Known issues:  There is some performances issue when set/getTimestamp
Bug 3037615
Bug 2770935
These bugs are very likely duplicate.
 
 
The following code will no longer work with 9203+ unless V8 flag is set to true
 
Timestamp start_dt_in = Timestamp.valueOf("2002-09-18 00:00:00");
Timestamp now_period_start_dt ;
PreparedStatement stmt = null;
ResultSet rs = null;
 
System.out.println("start_dt_in="+  start_dt_in );
 
try {
stmt = conn.prepareStatement( "SELECT TRUNC(?) FROM DUAL" );
stmt.setTimestamp( 1, start_dt_in );
rs = (OracleResultSet) stmt.executeQuery();
if ( rs.next() ) {
now_period_start_dt = rs.getTimestamp( 1 );
System.out.println("Curr Period Start="+  now_period_start_dt );
}
 
 
will generate
Exception in thread "main" java.sql.SQLException:
ORA-932: inconsistent datatypes
 
 
Reason : trunc ( )  supports Date columns and does not support  Timestamp  (this is an RDBMS issue).
So, you need to set the V8 flag to true
 
Another bug that changed the Date/Timetamp mapping is  2428427 to comly with
J2EE 1.3 CTS.  This was fixed in 9014 and it specific to classesdmx*.zip/jar
(the *dms* jar filed mainly used by iAS/OC4J).  These *dms* jar files, by the
default value for oracle.jdbc.J2EE13Compliant  is true.  in classes111.zip
classes12.jar and ojdbc14.jar/zip the default is false.
 
One can toggel this flag  true/false by
 
java -Doracle.jdbc.J2EE13Compliant=true|false
 
 
example of of sample runs:
 
query used :"select sysdate from dual"
classes12dms.jar used.
 
 
Driver Version      Object Type
==============      ===========
9.0.1.3.0         java.sql.Timestamp >> fix for 2428427 NOT included
9.0.1.4.0         java.sql.Date   >> fix for 2428427 INCLUDED
9.0.1.5.0         java.sql.Date   >> fix for 2428427 INCLUDE
 
In JDBC 9014+ ,to keep older (9013) behavior  simply run the application with
 
 
$java -Doracle.jdbc.J2EE13Compliant=false .....
 
 
However please note that J2EE 1.3 CTS require that Date to mapped to
java.sql.Date.