CODEWITHSUNDEEP
javajdbcresultset
user7324003
user7324003

Reputation: 49

Query regarding ResultSet

I am executing a Statement query and storing the data in ResultSet rs.

// if no record is returned by the query

if (!rs.next() ) {
Step1
}

// if atleast one record is returned by the query

if(rs.next()){
do {

  if (rs.getString(1).equalsIgnoreCase("0")){
          Step2
  }

  if (rs.getString(1).equalsIgnoreCase("1")){
         Step3
 }
}              while (rs.next());
}

However if i am getting only a single record from the query then no steps are executed. It would be of great help if anyone can point out the mistake.

Upvotes: 2

Views: 96

Answers (5)

Sisir Ranjan
Sisir Ranjan

Reputation: 97

You should not call rs.next() method twice. Following logic should work:

    if (!rs.next() ) {
       Step1
    }
    else{ // if atleast one record is returned by the query

        do {
          if (rs.getString(1).equalsIgnoreCase("0")){
                  Step2
          }
          if (rs.getString(1).equalsIgnoreCase("1")){
                 Step3
         }
        }while (rs.next());
    }

Upvotes: 2

Suresh Atta
Suresh Atta

Reputation: 121998

You have to understand what exactly next() method do. next() moves the cursor to next element. When you write next() inside if there the condition passed and there are no more elements when it comes to while.

And why don't you simplify your code by just doing 

while ( rs.next() ) { 
   if (rs.getString(1).equalsIgnoreCase("0")){
          Step2
  }

  if (rs.getString(1).equalsIgnoreCase("1")){
         Step3
 }
}

If you enter into while loop, there are items, otherwise No.

Upvotes: 5

Vaidas
Vaidas

Reputation: 1493

You are always skipping first element because you are calling .next() twice before taking an element. Try doing something like this:

if (rs.next()) {
    // At least one record returned
    do {
        if (rs.getString(1).equalsIgnoreCase("0")) {
            // Step2
        }

        if (rs.getString(1).equalsIgnoreCase("1")) {
            // Step3
        }
    } while (rs.next());
} else {
    // No records returned
}

Upvotes: 3

jack jay
jack jay

Reputation: 2503

Initially rs contains one record or more precisely points to result set having one record.

Now when if(!rs.next()) is called then rs moves to the next record in result set which is not there as you have only one record. So this if goes well. But again when you use if(rs.next()) then rs won't be having any record, hence the if won't execute.

Upvotes: 2

Vlad Bochenin
Vlad Bochenin

Reputation: 3072

From JavaDoc ResultSet:

Moves the cursor froward one row from its current position. A ResultSet cursor is initially positioned before the first row; the first call to the method next makes the first row the current row; the second call makes the second row the current row, and so on.

In your code you don't need second invocation of rs.next() because cursor already on first row.

Upvotes: 2

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