What happens if we call ResultSet getInt 0?
getInt(0) when Select query result just have one column of integer type? you may think that it will return the first column as an integer from the Query result set but unfortunately, it doesn’t. It throws InvalidColumnIndexException in JDBC because index for getXXX() or setXXX() in JDBC starts with 1.
How do I know if a ResultSet is empty?
The JDBC ResultSet doesn’t provide any isEmpty(), length() or size() method to check if its empty or not. Hence, when a Java programmer needs to determine if ResultSet is empty or not, it just calls the next() method and if next() returns false it means ResultSet is empty.
How do I get null ResultSet?
The wasNull() method of the ResultSet interface determines whether the last column read had a Null value. i.e. whenever you read the contents of a column of the ResultSet using the getter methods (getInt(), getString etc…) you can determine whether it (column) contains null values, using the wasNull() method.
How do I know if my ResultSet has data?
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.
Is before first Java?
The beforeFirst() method of the ResultSet interface moves the pointer of the current (ResultSet) object to the default position (before first), from the current position. Statement stmt = con. createStatement(); ResultSet rs = stmt.
Does ResultSet need to be closed?
You should explicitly close Statements , ResultSets , and Connections when you no longer need them, unless you declare them in a try -with-resources statement (available in JDK 7 and after). Connections to Derby are resources external to an application, and the garbage collector will not close them automatically.
How do you iterate through ResultSet?
To iterate the ResultSet you use its next() method. The next() method returns true if the ResultSet has a next record, and moves the ResultSet to point to the next record. If there were no more records, next() returns false, and you can no longer.
What is ResultSet interface Java?
The java. sql. ResultSet interface represents the result set of a database query. A ResultSet object maintains a cursor that points to the current row in the result set. The term “result set” refers to the row and column data contained in a ResultSet object.
Which driver is also known as thin driver?
Type-4 JDBC driver also known as ‘thin driver’ or Direct to Database Pure Java Driver. It is portable, the fastest among all JDBC drivers and database dependent.
What is a resultset?
A table of data representing a database result set, which is usually generated by executing a statement that queries the database. A ResultSet object maintains a cursor pointing to its current row of data. Initially the cursor is positioned before the first row.
How do you set the cursor of a resultset?
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. When a call to the next method returns false, the cursor is positioned after the last row.
What is resultset interface in Java?
ResultSet Interface is present in the java.sql package. It is used to store the data which are returned from the database table after the execution of the SQL statements in the Java Program. The object of ResultSet maintains cursor point at the result data. In default, the cursor positions before the first row of the result data.
How do you use resultset in a while loop?
A ResultSet object maintains a cursor pointing to its current row of data. Initially the cursor is positioned before the first row. The next method moves the cursor to the next row, and because it returns false when there are no more rows in the ResultSet object, it can be used in a while loop to iterate through the result set.