What If ResultSet Is Empty?

Can executeQuery return null?

Yes.

No, ResultSet returned by executeQuery(java.

lang.

String) method can never be null..

How do I check if a SQL query has returned nothing?

test if count == 0 . select FOUND_ROWS(); it will return the no. of rows returned by select query.

How check ResultSet getString is null?

Call rs. wasNull() right after calling rs. getString(). It returns a boolean telling you if the last value returned was a database null.

What is the meaning of ResultSet Type_scroll_insensitive?

TYPE_SCROLL_INSENSITIVE means that the ResultSet can be navigated (scrolled) both forward and backwards. You can also jump to a position relative to the current position, or jump to an absolute position. The ResultSet is insensitive to changes in the underlying data source while the ResultSet is open.

What does ResultSet next do?

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. A default ResultSet object is not updatable and has a cursor that moves forward only.

Why ResultSet next is false?

2 Answers. I believe it is the contract of try-with-resources to guarantee closing the resource specified in the try clause, after the expression finishes executing. I believe that the result set is also being closed at the end of the try block, hence calling next() returns false, because nothing is there.

Is the return type of next () method in ResultSet?

Return value This method returns a boolean value specifying whether the ResultSet object contains more rows. If there are no rows next to its current position this method returns false, else it returns true. Using this method in the while loop you can iterate the contents of the result set.

Is ResultSet a class?

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. … Update methods: Used to update the data in the columns of the current row.

What are the correct method of ResultSet if RS is object belongs to resultset?

What are the correct methods of ResultSet if rs is object belongs to ResultSet rs. getString(); rs. getInt();

Should ResultSet be closed?

You should close ResultSet and Statement explicitly because Oracle has problems previously with keeping the cursors open even after closing the connection. If you don’t close the ResultSet (cursor) it will throw an error like Maximum open cursors exceeded.

What happens if prepared statement is not closed?

Say if you don’t close a transaction or a connection, performance issues or even stability issues will occur both on the database server side as well as on the clients side. The limits on open cursors per session can be exceeded by not closing a result set or a statement.

How do you set ResultSet to first record?

The ResultSet object contains a cursor/pointer which points to the current row. Initially this cursor is positioned before first row (default position). You can move the cursor of the ResultSet object to the first row from the current position, using the first() method of the ResultSet interface.

Can ResultSet be null in Java?

No, ResultSet returned by executeQuery(java. lang. String) method can never be null. Moreover, the standard way to check whether a ResultSet is empty or not is to try setting its cursor to first row by using its first() and if it returns false it indicates that ResultSet is empty.

Does closing connection close ResultSet?

Closing Connection will close any Statement s that connection has created. Closing any Statement will close all ResultSet s that were created by that Statement . Doesn’t matter if Connection is poolable or not. Even poolable connection has to clean before returning to the pool.

Why is my ResultSet empty?

If the resultset is empty it means that no rows were returned for the query & thats the reason the following line is executed. RESULT SET HAS GOT SOMETHING.

How do you know if ResultSet contains data?

The next() method of the ResultSet interface moves the pointer of the current (ResultSet) object to the next row, from the current position. This method returns a boolean value specifying whether the ResultSet object contains more rows.

How do I know if a ResultSet is closed?

The ResultSet object contains a cursor/pointer which points to the current row. Initially this cursor is positioned before first row (default position). The isClosed() method of the ResultSet interface is used to determine whether the current ResultSet object is closed.

What happens if you call the method close on a ResultSet object?

Note: A ResultSet object is automatically closed by the Statement object that generated it when that Statement object is closed, re-executed, or is used to retrieve the next result from a sequence of multiple results. Calling the method close on a ResultSet object that is already closed is a no-op.