CODEWITHSUNDEEP
javajdbc
Nick Heiner
Nick Heiner

Reputation: 122450

ResultSet exception - before start of result set

I'm having trouble getting data from a ResultSet object. Here is my code:

    String sql = "SELECT type FROM node WHERE nid = ?";
    PreparedStatement prep = conn.prepareStatement(sql);
    int meetNID = Integer.parseInt(node.get(BoutField.field_meet_nid));
    prep.setInt(1, meetNID);

    ResultSet result = prep.executeQuery();
    result.beforeFirst();
    String foundType = result.getString(1);

    if (! foundType.equals("meet")) {
        throw new IllegalArgumentException(String.format("Node %d must be of type 'meet', but was %s", meetNID, foundType));
    }

The error trace:

Exception in thread "main" java.sql.SQLException: Before start of result set
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1072)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:986)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:981)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:926)
    at com.mysql.jdbc.ResultSetImpl.checkRowPos(ResultSetImpl.java:841)
    at com.mysql.jdbc.ResultSetImpl.getStringInternal(ResultSetImpl.java:5656)
    at com.mysql.jdbc.ResultSetImpl.getString(ResultSetImpl.java:5576)
    at nth.cumf3.nodeImport.Validator.validate(Validator.java:43)
    at nth.cumf3.nodeImport.Main.main(Main.java:38)

What am I doing wrong here?

Upvotes: 101

Views: 252672

Answers (7)

Kosala
Kosala

Reputation: 1

The error you're encountering, "Before start of result set," occurs because you're trying to retrieve data from the result set before moving the cursor to the first row of the result set. The 'beforeFirst()' method moves the cursor before the first row, and then you're immediately trying to retrieve data using result.getString(1), which is causing the exception.

Upvotes: 0

MmynameStackflow
MmynameStackflow

Reputation: 1251

Every answer uses .next() or uses .beforeFirst() and then .next(). But why not this:

result.first();

So You just set the pointer to the first record and go from there. It's available since java 1.2 and I just wanted to mention this for anyone whose ResultSet exists of one specific record.

Upvotes: 12

Pedro
Pedro

Reputation: 21

It's better if you create a class that has all the query methods, inclusively, in a different package, so instead of typing all the process in every class, you just call the method from that class.

Upvotes: 2

ryanprayogo
ryanprayogo

Reputation: 11817

You need to move the pointer to the first row, before asking for data:

result.beforeFirst();
result.next();
String foundType = result.getString(1);

Upvotes: 1

Dan
Dan

Reputation: 11069

You have to call next() before you can start reading values from the first row. beforeFirst puts the cursor before the first row, so there's no data to read.

Upvotes: 4

Vincent Ramdhanie
Vincent Ramdhanie

Reputation: 103135

Basically you are positioning the cursor before the first row and then requesting data. You need to move the cursor to the first row.

 result.next();
 String foundType = result.getString(1);

It is common to do this in an if statement or loop.

if(result.next()){
   foundType = result.getString(1);
}

Upvotes: 199

Paul Tomblin
Paul Tomblin

Reputation: 182782

You have to do a result.next() before you can access the result. It's a very common idiom to do

ResultSet rs = stmt.executeQuery();
while (rs.next())
{
   int foo = rs.getInt(1);
   ...
}

Upvotes: 11

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