Determining Number of Rows in a ResultSet
Hi,
Is there an easy way to determine the number of rows in a result set with TYPE_FORWARD_ONLY?
> > Try ResultSet rs = statment.executeQuery(...);
if(rs
== null){ //result set is empty}That is incorrect... it should have read:
ResultSet rs = statment.executeQuery(...);
if( ! rs.next() )
//result set is empty
you're right!! copy/paste from executeUpdate( ) api documentation about statements....
"a ResultSet object that contains the data produced by the given query; never null"
here's the catch though: that will advance your result set, which will throw off your cursor in a while loop (used to parse the results). requires you to reset the cursor before processing the result set.
Similar Messages
-
Trying to find the number of rows in a ResultSet
I am trying to find the number of rows in a ResultSet, using the following code:
rs = st.executeQuery(query);
rs.last(); // to move the cursor to the last row
System.out.println(rs.getRow());
However, I am getting this error:
java.sql.SQLException: [Microsoft][SQLServer 2000 Driver for JDBC]Unsupported method: ResultSet.last
Whats going wrong??praveen_potru wrote:
You might have not used scrollable result set..
Try like this:
stmt = conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);rs = stmt.executeQuery(sqlString);
// Point to the last row in resultset.
rs.last();
// Get the row position which is also the number of rows in the ResultSet.
int rowcount = rs.getRow();
System.out.println("Total rows for the query: "+rowcount);
cheersAnd I hope the OP would read it because the thread is a year old. -
How do you return the number of Rows in a ResultSet??
How do you return the number of Rows in a ResultSet? It's easy enough to do in the SQL query using COUNT(*) but surely JDBC provides a method to return the number of rows.
The ResultSetMetaData interface provides a method for counting the number of columns but nothing for the rows.
ThanksNo good way before JDBC2.0. u can use JDBC2.0 CachedRowSet.size() to retrieve the number of rows got by a ResultSet.
-
DB: Release 8.1.5.0.0
Server: DEC Alpha OSF1 V4.0F
Driver: thin, version?
We're using JDBC to access Oracle tables from classes loaded into the database with loadjava. I can execute a statement and get a ResultSet, but I haven't been able to find a way to get the number of rows in the ResultSet (since Oracle's implementation of JDBC doesn't include the getFetchSize method of ResultSet).
Is there another way to get the size of a ResultSet? If not, will Oracle be adding the getFetchSize method to their implementation soon?
Thanks.
null> > Try ResultSet rs = statment.executeQuery(...);
if(rs
== null){ //result set is empty}That is incorrect... it should have read:
ResultSet rs = statment.executeQuery(...);
if( ! rs.next() )
//result set is empty
you're right!! copy/paste from executeUpdate( ) api documentation about statements....
"a ResultSet object that contains the data produced by the given query; never null"
here's the catch though: that will advance your result set, which will throw off your cursor in a while loop (used to parse the results). requires you to reset the cursor before processing the result set. -
How to get the number of rows in a ResultSet
Hello,
I'm an intern and I'm trying to get the number of rows from result set in oracle using rs.last() and rs.beforeFirst() methods
but I got an error. Could Below is my sample code:
import java.sql.*;
public class SarueckConnect {
public static void main(String[] args) {
Connection con = null;
Statement stmt = null;
ResultSet re = null;
String[] ParamArray;
ParamArray = new String[24];
//Properties logon;
try {
Class.forName("oracle.jdbc.driver.OracleDriver"); //Loading the Oracle Driver.
con = DriverManager.getConnection
("jdbc:oracle:thin:@258.8.159.215:1521:test_DB","data","data"); //making the connection DB.
stmt = con.createStatement ();// Sending a query string to the database
//stmt.executeUpdate("UPDATE test_table set steuk = 6 WHERE steuk = 5");
ResultSet rs = stmt.executeQuery("SELECT mandt,kokrs,werks,arbpl,aufnr,vornr,ile01,"+
"lsa01,ism01,ile02,lsa02,ism02,ile03,lsa03,ism03,ile04,lsa04,ism04,steuk,matnr,budat,"+
"kostl,pernr,rueckid FROM test_table where steuk =6");
//Print the result out.
rs.last(); //This is the line which gives an error.
int rows = rs.getRow();
rs.beforeFirst();// I presume this is wrong to.
ParamArray = new String[24*rows];
int counter=0;
while (rs.next()) {
for (int i = 1; i <= 24; i++){
ParamArray[i-1+(counter*24)] = rs.getString(i);
System.out.print(rs.getString(i) + '\t');
System.out.println();
counter++;
} catch(Exception e) {
e.printStackTrace();
} finally {
try
if(stmt != null) stmt.close();
if(con != null) con.close();
} catch (Exception exception) {
exception.printStackTrace();
TryBapi sap = new TryBapi(ParamArray);
}When I run the code I do have the following ERROR Message:
java.sql.SQLException: Invalid operation for forward only resultset : last
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:179)
at oracle.jdbc.driver.BaseResultSet.last(BaseResultSet.java:91)
at SarueckConnect.main(SarueckConnect.java:28)Please could any body Help me out here to figure out how to correct this?
Any Help would be highly apprecited.make your result set scrollable...Not such a good idea. With Oracle, the JDBC driver will read and cache all the ResultSet in memory (with other DBMSs/drivers the behavior will probably be different, but you will still have some unnecessary overhead).
You can do the caching yourself if you think it's worth it. If the piece of code you posted is why you need this for, then use a List or Vector and you won't need to know the size upfront.
Alin,
The jTDS Project. -
Getting the number of rows returned from ResultSet
Hi,
Does anyone know a method to get the number of rows returned with a query using the Resultset class?
Thanks.Hi 281080,
If your database and JDBC driver support it, in order to use the solution that da-alexj has suggested, you need to create a 'scrollable' "ResultSet" -- the javadoc for method "createStatement()" (in class "java.sql.Connection") has more details.
However, I have found with Oracle 8.1.7.4 database and Oracle (thin) JDBC driver, that part of their implementation of the "last()" method (in class "java.sql.ResultSet") is to actually iterate through the entire "ResultSet" in order to reach the last row. If your "ResultSet" is very large (I tested it with a 100,000 row "ResultSet"), this will take a long time.
Just wanted to make you aware of that.
Of-course, this may be irrelevant to you since I didn't see any mention in your post of what database and JDBC driver you are using.
Hope this has helped you, anyway.
Good Luck,
Avi. -
How to know the number of rows of a ResultSet
Hello.
I'm trying to detect the number of rows of a query result before making all the results.next().
Until know, my way was:
ResultSet results = sql.executeQuery();
while( results.next() )
int i = 0;
... do stuff ...
i++;
out.println("The number of rows is: " + i);
But I would like to know the value of 'i' just after 'executeQuery'.
Does anybody have any experienc?
Regards.How about like this???
>
ResultSet results = sql.executeQuery();results.last();
i = results.getRow();
results.first();
while( results.next() )
int i = 0;
... do stuff ...
i++;
out.println("The number of rows is: " + i);
But I would like to know the value of 'i' just after
'executeQuery'.
Does anybody have any experienc?
Regards. -
Setting the maximum number of rows in a ResultSet
Hi everybody,
Anyone knows if it is possible to set the maximum number of rows to obtain in a ResultSet using JDBC 2.0, and if so, how to do it?
Thanks in advance.Statement st = con.createStatement();
st.setFetchSize(no_of_rows_here);
ResultSet rs = st.executeQuery(query);Sudha -
Determine number of rows from javascript so I can hide if zero
Hi All,
Found a great article which I adapted to use the link on a report to delete a row in db and remove from table (without a refresh).
It works great except I want the region to not display when there are no rows left.
Currently it shows "No Data Found" but because the page does not submit the region does not hide.
Here is the Java code:
function ackMsg(p_this, p_empno) {
// get the table row on which the user clicked
var tr = $(p_this).closest('tr');
// perform an asynchronous HTTP AJAX request using jQuery
$.ajax({
type: "POST",
url: "wwv_flow.show",
data: {
p_flow_id: $('#pFlowId').val(),
p_flow_step_id: $('#pFlowStepId').val(),
p_instance: $('#pInstance').val(),
x01: p_empno, // assign p_empno to the g_x01 global variable
p_request: "APPLICATION_PROCESS=ack_message" // refer to the application process
beforeSend: // executes while the AJAX call is being processed
function() {
// delete following HTML classes from the table row element
// could be possibly theme dependent
tr.removeClass('even');
tr.removeClass('odd');
// use jQuery's animate function to give the table row, and its children, a red background
tr.children().hover(function() {
tr.children().animate({'backgroundColor': '#00cc00'}, 300);
}, function() {
tr.children().animate({'backgroundColor': '#00cc00'}, 300);
tr.children().animate({'backgroundColor': '#00cc00'}, 300);
success: // to be called if the request succeeds
function() {
jQuery(p_this).trigger('apexrefresh');
// jQuery has difficulties animating inline elements
// that's why we wrap them in a div, which is a block element
tr.children().wrapInner('<div>').children().fadeOut(400, function() {
tr.remove(); // visually remove the row from the report
I did some Googling to add the line ' jQuery(p_this).trigger('apexrefresh');' which refreshes just that report.
What I think I need to do is add a check for number of rows left after the refresh then if = 0 do full page refresh to allow the region condition to hide it.
Unfortunately after hours on Google I can't find how to check how many rows are in the table.
PS the function is called from the link in the report like this onclick="ackMsg(this, #ACK#)"
Please help
AT
Edited by: user1678248 on May 13, 2013 9:39 PM
Edited by: user1678248 on May 13, 2013 9:40 PM1)
When you set a column to hidden in a classic report using the method I described, it creates hidden form elements for that column.
<tt><input type="hidden" name="f01" value="" id="f01_0002"></tt>
You should inspect the source to figure out the name value.
Since this belongs to the wwv_flow form, we can therefore get this data with: wwv_flow.f01
Alternatively, you could have used the apex_item API to achieve the same result, which probably gives a bit better control.
http://docs.oracle.com/cd/E37097_01/doc/doc.42/e35127/apex_item.htm#CHDBFHGA
select apex_item.hidden(1, col) || col col
from table
Set that column to a standard report column so it doesn't escape the html.
You can also reference the data in these fields using PL/SQL using the apex_application API:
http://docs.oracle.com/cd/E37097_01/doc/doc.42/e35127/apex_app.htm#CHDGJBAB
2)
As above, setting the column to hidden creates hidden elements on the page. It is simply f01 because that is the only hidden field I would have on my page. With four reports on the page, you would need to be careful not to do the same on the other reports, as you would get inaccurate data. For each report, setting columns to hidden always starts with f01. In that, you would be best to use the apex_item API.
I actually initially ran into this issue when i had a tabular form on the same page as a report with hidden fields, which was causing conflicts in the page processes.
Hope it helps. -
Getting number of rows in a resultset
I am moving my application from JDBC 1.0 to JDBC 2.0. In JDBC 1.0, I used to fire separate query for count(*) to get the no. of rows in results but with JDBC 2.0 is there way that I dont need to execute a separte query to get no. or rows in a resultset.
Thanks
SushilThere is Sushil if your driver supports it. It can be done with scrollable ResultSets.
Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
ResultSet rs = stmt.executeQuery("sql");
if (rs != null) {
rs.last();
int numRows = rs.getRow();
// be sure to set rs.beforeFirst() if you want to process the ResultSet
} -
Determine Number of rows in Internal Table
Hi,
I have defined my internal table as follows:
TYPES : BEGIN OF ABC_KEY,
FIELD1(2) TYPE C,
FIELD2(1) TYPE C,
FIELD3(8) TYPE N,
END OF ABC_KEY.
DATA: itab1 TYPE TABLE OF ABC_KEY
WITH KEY FIELD1,
wa_lines_1 LIKE LINE OF itab1.
How can I retrieve the number of rows in Internal Table?
Thanks.
Regards,
bw_newbieYou can define the number of rows of the internal table using the DESCRIBE itab command .
As the rest have already stated a sample code snippet .
For more info type in DESCRIBE in your prgram and click on (F1) by placing the cursor on DESCRIBE .
You will find more options as to how you can use the DESCRIBE command according to your requirement .
Thanks ,
Hari -
Determining number of rows in blocks
Hello
Assume 8k blocksize
How can I know, how many rows will fit into one block?
CheersNot really no. What's a row look like? NUMBERs? VARACHARs? DATE types? If VARCHARs, the amount of data actually being stored could vary hugely.
If you already have some data loaded in a table somewhere, you may try sampling existing data to give you some idea.
Try something like this:
MBOBAK@mstmfgpep> create table test_rows nologging as select * from dba_tables;
Table created.
MBOBAK@mstmfgpep> select count(*) from TEST_ROWS;
COUNT(*)
1589
1 row selected.
MBOBAK@mstmfgpep> l
1* select dbms_rowid.ROWID_to_absolute_fno(rowid,'MBOBAK','TEST_ROWS'),dbms_rowid.ROWID_BLOCK_NUMBER(rowid),count(*) rows_in_block from test_rows group by dbms_rowid.ROWID_to_absolute_fno(rowid,'MBOBAK','TEST_ROWS'),dbms_rowid.ROWID_BLOCK_NUMBER(rowid)
MBOBAK@mstmfgpep> /
DBMS_ROWID.ROWID_TO_ABSOLUTE_FNO(ROWID,'MBOBAK','TEST_ROWS') DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID) ROWS_IN_BLOCK
6 212 31
6 216 32
6 218 31
6 221 31
6 222 32
6 224 31
6 255 31
6 206 32
6 213 32
6 220 31
6 223 31
6 225 32
6 227 31
6 239 30
6 245 31
6 208 32
6 211 32
6 240 30
6 243 31
6 247 33
6 253 34
DBMS_ROWID.ROWID_TO_ABSOLUTE_FNO(ROWID,'MBOBAK','TEST_ROWS') DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID) ROWS_IN_BLOCK
6 204 32
6 228 31
6 230 31
6 232 31
6 234 31
6 235 30
6 250 41
6 254 33
6 256 31
6 207 31
6 237 30
6 241 31
6 242 32
6 244 32
6 246 31
6 248 38
6 251 34
6 209 32
6 231 31
6 236 30
6 238 30
DBMS_ROWID.ROWID_TO_ABSOLUTE_FNO(ROWID,'MBOBAK','TEST_ROWS') DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID) ROWS_IN_BLOCK
6 210 32
6 214 32
6 215 32
6 219 31
6 226 31
6 205 32
6 229 31
6 252 34
50 rows selected.
MBOBAK@mstmfgpep> This will count the number of rows that you're actually getting in each block. Warning, on a large table, this could take a very long time to run and produce lots of output. But you should be able to use the technique to sample how many rows/block you see on various tables.
Hope that helps,
-Mark -
How do I find out the number of rows in a resultset ?
Without scrolling it.
And explain to me, oh sarcastic one, how it wouldn't be a better idea to put that data into a datastructure and pass that back.1. Performance with very large ResultSet objects for which only sparse data is desired (that's what pages are for).
2. Resource optimization.
3. Efficient sequential processing.
4. The ability to intelligently determine based on resource usage whether to page the results or use your implementation for small ResultSet objects.
Answering your points:
1. I just showed him a very easy way to get the size.
2. I don't see any advantage of a collection (if that's what you were envisioning) over a paged ResultSet. Actually the ResultSet is a collection of sorts.
3. Your data is reliant on the connection initially anyway. The collection would only provide an advantage in the possibly short window while the data was being viewed.
4. You can always resort a ResultSet by requerying. -
How do I get the number of rows in a ResultSet?
I checked the API, but didn't find a method that does this.
You could try calling last() then getRow() to get the
no of rows ...You probably need a scrollable resultset to do this, so that you can
rewind back to the start and read the data in.
I imagine you want to get a count, to size an array, before reading in the data ? Why not load it in an arraylist, then convert to an array afterwards ?
regards,
Owen -
Same old...number of rows in a resultset...but a different question
Hi,
I'm writing a code to generate report from the database. Everything is working absolutely fine. Now the problem is that when I try to check whether any row has been returned, I'm not able to do it correctly. What is happening is that the column heading is also being considered as a data and being written to the output file. I want that if there is no data ( excepting the column headings ) the program should terminate. Can anyone help me out of this? Thanks & regards,
FaisalHi,
Plz find the code below :
import java.io.*;
import java.sql.*;
import java.util.*;
public class JDBC8
public static void main (String[] args) throws Exception
Connection con = null;
final String query = "select TNAME,TABTYPE from tab where tname like '%FAZ%'";
Statement stmt = null;
int ctr=0;
int maxColLength = 0;
String fileName = "";
ResultSet rs = null;
FileNameCreater obj = new FileNameCreater();
fileName = obj.getFileName();
int t = 0;
System.out.println("Created file : " +fileName);
try {
// load the driver
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
catch (java.lang.ClassNotFoundException e)
System.err.print("ClassNotFoundException.");
System.err.println(e.getMessage());
System.out.println("Connecting to the database. Please wait....");
try {
// define the connection URL. establish the connection.
con = DriverManager.getConnection("jdbc:odbc:DSN1","mis","abcdef#0");
if ( con.isClosed() )
System.out.println("Failed to connect to the database. Press enter to continue.");
System.in.read();
else
System.out.println("Connected to the database.");
System.out.println("Processing...Please be patient...");
// create a statement object
stmt = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
// Execute a query
rs = stmt.executeQuery(query);
ResultSetMetaData rsmd = rs.getMetaData();
rs.first();
System.out.println("check 1 = " + rs.getRow());
System.in.read();
int cntr = 0;
String tempStr = "";
String tempLbl = "";
boolean flag = false;
boolean inWhile = false;
rs.beforeFirst();
while ( rs.next() )
System.out.println("entered while");
System.in.read();
tempStr = rs.getString(++cntr);
tempLbl = rsmd.getColumnLabel(cntr);
System.out.println("cntr = " + cntr + " tempStr = " + tempStr + " tempLbl = " + tempLbl);
if ( tempStr == tempLbl )
flag = true;
else
flag = false;
inWhile = true;
if ( inWhile )
rs.beforeFirst();
FileWriter writer = new FileWriter(fileName);
BufferedWriter buf_Writer = new BufferedWriter(writer);
System.out.println("Processing started...");
int colCount = 0;
colCount = rsmd.getColumnCount();
String colLabel = "";
for ( int x = 1; x <= colCount; x++ )
colLabel = rsmd.getColumnLabel(x);
buf_Writer.write(colLabel);
if ( x < colCount )
buf_Writer.write("|");
buf_Writer.newLine();
rs.beforeFirst();
// Process the results
while(rs.next())
ctr++;
for (int i = 1; i <= colCount; i++)
String columnValue = rs.getString(i);
buf_Writer.write(columnValue);
if ( i < colCount )
buf_Writer.write("|");
buf_Writer.newLine();
buf_Writer.close();
catch (SQLException e)
System.err.println("SQLException : " + e.getMessage());
finally
try
// Close the resultset, statement and connection objects.
if (rs != null)
rs.close();
if (stmt != null)
stmt.close();
if (con!=null)
con.close();
catch(Exception ex)
System.out.println("Exception encountered: "+ ex.getMessage());
System.out.println("Program completed successfully.");
} // end of main
} // end of class
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