Java ResultSet how to check if there are any results

Question

Resultset has no method for hasNext  I want to check if the resultSet has any value  is this the correct way   if   resultSet next           System out println  no data

User · Answer

To be totally sure of rather the resultset is empty or not regardless of cursor position, I would do something like this:

public static boolean isMyResultSetEmpty(ResultSet rs) throws SQLException {
    return (!rs.isBeforeFirst() && rs.getRow() == 0);
}

This function will return true if ResultSet is empty, false if not or throw an SQLException if that ResultSet is closed/uninitialized.

User · Answer

You would usually do something like this   while   resultSet next              Read the next item    resultSet getString  columnName        If you want to report an empty set  add a variable counting the items read  If you only need to read a single item  then your code is adequate

User · Answer

Why not use rs getRow     int getRow              throws SQLException Retrieves the current row number  The first row is number 1  the second number 2  and so on  Note Support for the getRow method is optional for ResultSets with a result set type of TYPE FORWARD ONLY  Returns  the current row number  0 if there is no current row Throws  SQLException - if a database access error occurs or this method is called on a closed result set SQLFeatureNotSupportedException - if the JDBC driver does not support this method Since  1 2   For me check  if  rs getRow      0   seems to work just fine

User · Answer

I created the following method to check if a ResultSet is empty   public static boolean resultSetIsEmpty ResultSet rs               try              We point the last row         rs last            int rsRows rs getRow       get last row number          if  rsRows    0                return true                        It is necessary to back to top the pointer  so we can see all rows in our ResultSet object          rs beforeFirst            return false       catch SQLException ex                       return true            It is very important to have the following considerations   CallableStatement object must be setted to let to ResultSet object go at the end and go back to top   TYPE SCROLL SENSITIVE  ResultSet object can shift at the end and go back to top  Further can catch last changes   CONCUR READ ONLY  We can read the ResultSet object data  but can not updated   CallableStatement proc   dbconex prepareCall select  ResultSet TYPE SCROLL SENSITIVE  ResultSet CONCUR READ ONLY

User · Answer

That s correct  initially the ResultSet s cursor is pointing to before the first row  if the first call to next   returns false then there was no data in the ResultSet   If you use this method  you may have to call beforeFirst   immediately after to reset it  since it has positioned itself past the first row now   It should be noted however  that Seifer s answer below is a more elegant solution to this question

User · Answer

That would work if you want to see if there are any rows in the result set yes    Note that next   always moves to the next row  so if you are planning on doing any reading from the result set you need to take that into account   Usual usage with ResultSet  when simply reading  is   while  resultSet next             read from the row here         Which obviously won t work correctly if you invoked next   once already to check if the result set was empty  so watch out for that  Although there are methods for  backing up   they are not supported for all types of result sets

User · Answer

you can do something like this  boolean found   false   while   resultSet next           found   true      resultSet getString  column name       if   found      System out println  No Data

User · Answer

I think the easiest way for checking result set is via CollectionUtils under package org apache commons collections CollectionUtils  if CollectionUtils isNotEmpty resultList              do some stuff          This will check for null as well as empty result set condition    For more detail information you can refer to the following doc   CollectionUtils

User · Answer

you could always do the next up front  and just do a post loop check  if   resultSet next           System out println  no data      else        do          statement s        while  resultSet next

User · Answer

Best to use ResultSet next   along with the do       while   syntax for this   The  check for any results  call ResultSet next   moves the cursor to the first row  so use the do       while   syntax to process that row while continuing to process remaining rows returned by the loop   This way you get to check for any results  while at the same time also processing any results returned   if resultSet next         Checks for any results and moves cursor to first row      do      Use  do   while  to process the first row  while continuing to process remaining rows        while  resultSet next

User · Answer

ResultSet rs   rs executeQuery    if rs next        rs   rs executeQuery      while rs next              do code part       else       else if no result set     It is better to re execute query because when we call if rs next          first row of ResultSet will be executed and after it inside while rs next          we ll get result from next line  So I think re-execution of query inside if is the better option

User · Answer

Assuming you are working with a newly returned ResultSet whose cursor is pointing before the first row  an easier way to check this is to just call isBeforeFirst    This avoids having to back-track if the data is to be read   As explained in the documentation  this returns false if the cursor is not before the first record or if there are no rows in the ResultSet   if   resultSet isBeforeFirst               System out println  No data           nbsp

User · Answer

Initially  the result set object  rs  points to the BFR  before first record   Once we use rs next    the cursor points to the first record and the rs holds  true   Using the while loop you can print all the records of the table  After all the records are retrieved  the cursor moves to ALR  After last record  and it will be set to null  Let us consider that there are 2 records in the table   if rs next    false          there are no records found            while  rs next    true          print all the records of the table         In short hand  we can also write the condition as while  rs next

User · Answer

I ve been attempting to set the current row to the first index  dealing with primary keys   I would suggest  if rs absolute 1        System out println  We have data      else       System out println  No data        When the ResultSet is populated  it points to before the first row  When setting it to the first row  indicated by rs absolute 1   it will return true denoting it was successfully placed at row 1  or false if the row does not exist  We can extrapolate this to  for int i 1  rs absolute i   i           Code     which sets the current row to position i and will fail if the row doesn t exist  This is just an alternative method to  while rs next           Code

User · Answer

By using resultSet next   you can easily get the result  whether resultSet containing any value or not  ResultSet resultSet   preparedStatement executeQuery    if resultSet next       resultSet contain some values else     empty resultSet

User · Answer

The best thing for to do is to check the first row so that when you intend to get the data you can avoid the mistake of skipping a row  Something like     if   resultSet first       System out println  no data

User · Answer

This is a practical and easy read piece I believe           if  res next                  do                       successfully in  do the right things                 while  res next               else                 no results back  warn the user

User · Answer

According to the most viable answer the suggestion is to use  isBeforeFirst     That s not the best solution if you don t have a  forward only type    There s a method called   first     It s less overkill to get the exact same result  You check whether there is something in your  resultset  and don t advance your cursor    The documentation states         false if there are no rows in the result set    if rs first           do stuff              You can also just call isBeforeFirst   to test if there are any rows returned without advancing the cursor  then proceed normally       SnakeDoc Sep 2  14 at 19 00    However  there s a difference between  isBeforeFirst    and  first     First generates an exception if done on a resultset from type  forward only     Compare the two throw sections   http   docs oracle com javase 7 docs api java sql ResultSet html isBeforeFirst   http   docs oracle com javase 7 docs api java sql ResultSet html first    Okay  basically this means that you should use  isBeforeFirst  as long as you have a  forward only  type  Otherwise it s less overkill to use  first

User · Answer

if resultSet first       else        system out println  No raw or resultSet is empty        Because if ResultSet has no raw then resultSet first returns false

User · Answer

if   resultSet isAfterLast           System out println  No data          isAfterLast   also returns false for empty result set but since cursor is before first row anyways  this method seems more clear

User · Answer

ResultSet result   stmt executeQuery sqlQuery   if   result next        status    ERROR   else     status    SUCCESS

[java] Java ResultSet how to check if there are any results

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