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Updated: Problem with executing SQL query from Java

Updated:
so as per the suggestions i changed all the column name to strings and added prepared statements-
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/minor","root","alphabet")) {
Statement st = conn.createStatement();
PreparedStatement stmt= conn.prepareStatement("select * FROM ? where name=? ;");
PreparedStatement stmt2= conn.prepareStatement("select * FROM ? where name=? ;");
stmt.setString(1, day_1);
stmt.setString(2, faculty1);
stmt2.setString(1,day_1);
stmt2.setString(2, faculty2);
ResultSet rs=stmt.executeQuery();
ResultSet rs1= stmt.executeQuery();
The day and faculty is retrieved from input screen, the queries work just fine in mysql workbench but the 'select' keyword goes missing when i try to run it from Java, see the following error-
The faculty1, faculty2 is retrieved from the following-
The database looks like this-

I would recommend to use PreparedStatement instead of Statement, then at least you can bind your variables;
You query select from time_interval from day_selected is not correct, I don't think that it will execute anywhere, you need to have something between select and from, and not two from in one statement.

How to get the full query that a PreparedStatement is about to execute in DB2?

I'm working on a dynamic web project and using the PreparedStatement to execute the SQL queries against the DB2 database.
String myQuery = "select id from user where name = ?";
PreparedStatement stmt = connection.prepareStatement(myQuery);
stmt.setString(1, test);
ResultSet resultSet = statement.executeQuery();
How can I receive the full SQL query that is about to be executed on the DB2 server in the console?

If you are familiar with Debugging options in Eclipse. You may try the following:
Set a Breakpoint at ResultSet resultSet = statement.executeQuery();
Right click your application, say Debug As select Java Application (or Whatever applicable in your case i.e. may be SpringBoot App etc.
Perform step that gets you to code mentioned in the Question.
If you check Variables tab in Debug Perspective of Eclipse, you will find variables like myQuery , stmt (according to your code)
Whatever you see as value of stmt would be the full SQL query you need.
Also, if you don't want to keep looking at this variable always you may try Java Logging and Print your Full SQL query in Logs.

how to update a record in mysql through java

I am currently trying to code a java program for a school project that has a mysql database of sportsclub members. I want to use the id of the members in order to change the number of classes that someone skipped. However my Java code always fails to run and outputs the exception message. My database is called demo1 and the field im trying to update is Consecutiveskips. The id field is called (id)

Simplest way to update record is through statement
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection oCon = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "root");
String query="Update Demo1 SET Consecutiveskips=? where id=?";
PreparedStatement preparedStatement = oCon.prepareStatement(query);
preparedStatement.setInt(1, 233);
preparedStatement.setInt(2, 4);
In your code you are using setInt(6,1) but there is no 6th index present.
You should use
preparestaement.setInt(1,"yourconsicutiveskipvalue");
preparestaement.setInt(2,"idvalue");
Moreover, make sure to have mysql-connector.jar in classpath

how to insert current date in mysql database using jsp?

I am trying to insert the date using this code:
java.sql.Timestamp sqlNow=new java.sql.Timestamp(new java.util.Date().getTime());
pstTimestamp(1,sqlNow);
On running the code, the result is successful, but the date is not been displayed in the database.

You should use PreparedStatement and use it to set the date as follows :-
PreparedStatement pstmt = con.prepareStatement("INSERT INTO table_name (col_name) VALUES (?)");
pstmt.setTimestamp(1, new java.sql.Timestamp(new java.util.Date().getTime()));
pstmt.executeUpdate();
Read more here

Try this
PreparedStatement ps = con.prepareStatement("INSERT INTO table_name (col_name) VALUES (now())");
ps.executeUpdate();
use now() so that it will get the date in db format only.

Make sure you commit after running the command. Or make sure auto commit is enabled on the connection.

Just you need to provide the java.sql.Timestamp class object to the PreparedStatement object rest of work will be done by driver.
I think there is a problem in your code while setting place holder's value(parameter).
Use pstmnt.setTimestamp(int index, java.sql.Timestamp timestamp_object);
now execute your query as: pstmnt.executeUpdate();

java.sql.SQLRecoverableException: No more data to read from socket

I have a database table in oracle which has a column of type DATE. It looks like the table below
TABLE1
ID PRODUCT_NAME ITEM_CNT ENTERED_DATE
1 prod1 500 2012-07-01
2 prod2 1000 2012-06-30
in my java code, I want to get the total item_cnt for a certain date range. here is the code sample
String sql = "select sum(item_cnt) from table1 where entered_date between ? and ?";
Connection conn = null;
PreparedStatement pstmt = null;
ResultSet rset = null;
try{
conn = getConnection(url, user, passwd);
pstmt = conn.prepareStatement(sql);
pstmt.setDate(1, java.sql.Date.valueOf(from_date)); //from_date is a string of "yyyy-mm-dd"
pstmt.setDate(2, java.sql.Date.valueOf(to_date)); //to_date is a string of "yyyy-mm-dd"
rset = pstmt.executeQuery();
....
}catch(SQLException e){
//do something
} finally{
//clean up
}
This code was running fine for a while until three days ago, I start getting the following exception at line pstmt.executeQuery();
java.sql.SQLRecoverableException: No more data to read from socket
at oracle.jdbc.driver.T4CMAREngine.unmarshalUB1(T4CMAREngine.java:1157)
at oracle.jdbc.driver.T4CTTIfun.receive(T4CTTIfun.java:290)
at oracle.jdbc.driver.T4CTTIfun.doRPC(T4CTTIfun.java:192)
at oracle.jdbc.driver.T4C8Oall.doOALL(T4C8Oall.java:531)
at oracle.jdbc.driver.T4CPreparedStatement.doOall8(T4CPreparedStatement.java:207)
at oracle.jdbc.driver.T4CPreparedStatement.executeForDescribe(T4CPreparedStatement.java:884)
at oracle.jdbc.driver.OracleStatement.executeMaybeDescribe(OracleStatement.java:1167)
at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1289)
at oracle.jdbc.driver.OraclePreparedStatement.executeInternal(OraclePreparedStatement.java:3584)
at oracle.jdbc.driver.OraclePreparedStatement.executeQuery(OraclePreparedStatement.java:3628)
at oracle.jdbc.driver.OraclePreparedStatementWrapper.executeQuery(OraclePreparedStatementWrapper.java:1493)
I tried to search for answers but couldn't find anything that really explains it. then I changed my sql query to
"select sum(item_cnt) from table1 where entered_date between to_date(?, 'yyyy-mm-dd') and to_date(?, 'yyyy-mm-dd')";
and instead of setting date, I changed the prepared statement to the following
pstmt.setString(1, from_date);
pstmt.setString(2, to_date);
Then the exception is gone.
Another confusion is, when I populate my table, I am still using the following
pstmt.setDate(1, java.sql.Date.valueOf(date)); //date is a string of format "yyyy-mm-dd"
and it is still working. only the select statement was giving me exceptions.
Now everything is working but I really want to know why. Anyone knows?
I did upgrade my java to 1.7.0_03-b05 recently. and I am using ojdbc6.jar. The oracle is 11g. Could this be the driver's problem? is ojdbc7 out?

I was facing this exception while working over JDBC with IBM WAS 7.0, I had performed a JCA lifecycle management operation on data source. Which is like controlling the runtime status of the data source. Purge removes the contents of connection pool for the data source. However, in WAS this purging the pool will not affect the ongoing transactions. Check on your side.
Another thing which I performed was; the disk space was full on directory where Oracle was installed, I added extra space over that.

As a best practice, I stay away from java.sql.Date class and use to_date() and to_char() functions while dealing with Dates in Java with Oracle.