SQL ResultSet Objects Overview

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Questions and Answers

What is a characteristic of a default ResultSet object?

It moves forward only and is not updatable. (correct)

It allows backward scrolling through the rows.

It supports multi-row retrieval simultaneously.

It can only be updated once.

Which method can be used to advance the cursor in a ResultSet object?

moveToNext()

getNext()

next() (correct)

advance()

Why is it recommended to read result set columns from left to right?

To ensure maximum portability of the code. (correct)

To optimize memory usage during retrieval.

To avoid data type mismatches.

To retain the order of execution in SQL queries.

What happens when a getter method is called with a column name that appears multiple times in a result set?

The value of the first matching column is returned. Signup and view all the answers

What is the JDBC method to create a scrollable and updatable ResultSet?

con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE) Signup and view all the answers

How does a JDBC driver handle data type conversion for getter methods?

It converts SQL types to Java types as specified in the getter method. Signup and view all the answers

What is the default starting position of the cursor in a ResultSet object?

Before the first row. Signup and view all the answers

When using column names to retrieve values, how is case sensitivity handled?

Column names are case insensitive. Signup and view all the answers

What type of ResultSet can display changes made by other users?

Type scrollable and updatable ResultSet. Signup and view all the answers

What is the purpose of the SQL AS clause in relation to column names?

To ensure column names uniquely refer to intended columns. Signup and view all the answers

Which JDBC version introduced a set of updater methods to the interface?

JDBC 2.0 Signup and view all the answers

How can a programmer update a column value in a ResultSet?

By moving to the desired row and using an update method. Signup and view all the answers

What does the moveToInsertRow method do in a ResultSet?

Moves the cursor to a special staging area for new rows. Signup and view all the answers

When is a ResultSet object automatically closed?

When the associated Statement object is closed or re-executed. Signup and view all the answers

Which statement correctly describes the updater methods utilized in a ResultSet?

They may be used for both updating existing rows and inserting new rows. Signup and view all the answers

What is a necessary step before calling the updateRow method in a ResultSet?

The target row must be positioned using an absolute or relative cursor movement. Signup and view all the answers

Which method provides metadata about the columns of a ResultSet?

ResultSet.getMetaData Signup and view all the answers

What is the first operation performed to insert a new row in a ResultSet?

Move the cursor to the insert row. Signup and view all the answers

Which of the following is NOT a function of the ResultSet object's updater methods?

Delete existing rows from the ResultSet. Signup and view all the answers

A ResultSet object maintains a ______ pointing to its current row of data.

cursor Signup and view all the answers

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

updatable Signup and view all the answers

The ______ method is used to move the cursor to the next row in the ResultSet.

next Signup and view all the answers

Column names used as input to getter methods are ______ insensitive.

case Signup and view all the answers

Columns in a ResultSet are numbered starting from ______.

1 Signup and view all the answers

For maximum portability, result set columns should be read in ______-to-right order.

left Signup and view all the answers

A JDBC driver attempts to convert the underlying data to the ______ type specified in the getter method.

Java Signup and view all the answers

When columns are not explicitly named in the query, it is best to use ______ numbers.

column Signup and view all the answers

To create a scrollable ResultSet, the statement must include ______.

TYPE_SCROLL_INSENSITIVE Signup and view all the answers

The JDBC specification provides a table showing the allowable mappings from SQL types to ______ types.

Java Signup and view all the answers

The programmer should ensure that column names uniquely refer to the intended columns using the SQL ______ clause.

AS Signup and view all the answers

In a scrollable ResultSet object, the cursor can be moved backwards and forwards to an ______ position.

absolute Signup and view all the answers

The updateRow method is used to update the data source table from which the ResultSet object ______ was derived.

rs Signup and view all the answers

An updatable ResultSet object serves as a staging area for building a row to be ______.

inserted Signup and view all the answers

The method moveToInsertRow moves the cursor to the ______ row.

insert Signup and view all the answers

A ResultSet object is automatically closed when the Statement object that generated it is ______.

closed Signup and view all the answers

The ______ object provides information about the number, types, and properties of a ResultSet object's columns.

ResultSetMetaData Signup and view all the answers

The cursor must be moved to the insert row before calling the ______ method.

insertRow Signup and view all the answers

To update a column value in a ResultSet, the programmer uses specific ______ methods.

updater Signup and view all the answers

The first operation performed to insert a new row in a ResultSet involves moving the cursor to the ______ row.

insert Signup and view all the answers

Study Notes

ResultSet Object

A ResultSet object is a table of data generated by executing a SQL query.
It acts as a cursor that points to the current row in the result set.
The initial position of the cursor is before the first row.
Method next() moves the cursor to the next row.
Looping through the result set is done with a while loop that checks if next() returns false, indicating no more rows.
By default, ResultSet objects are not updatable and have a forward-only cursor.

To create scrollable and updatable ResultSet objects, use the following code:

Statement stmt = con.createStatement(
                                 ResultSet.TYPE_SCROLL_INSENSITIVE,
                                 ResultSet.CONCUR_UPDATABLE);
  ResultSet rs = stmt.executeQuery("SELECT a, b FROM TABLE2");

ResultSet objects provide methods like getBoolean, getLong, and getString to retrieve column values from the current row using either column index or column name.
Column indices start from 1.
Using column indices generally results in better performance.
For portability, read columns within each row from left to right, and read each column only once.
ResultSet objects can be updated using update methods. These methods allow for updating column values in the current row or inserting values into a new row.

For updating a column in the current row, use code similar to this:

rs.absolute(5); // moves the cursor to the fifth row of rs
      rs.updateString("NAME", "AINSWORTH"); // updates the
         // NAME column of row 5 to be AINSWORTH
      rs.updateRow(); // updates the row in the data source

To insert a new row: ```java rs.moveToInsertRow(); // moves cursor to the insert row rs.updateString(1, "AINSWORTH"); // updates the // first column of the insert row to be AINSWORTH rs.updateInt(2,35); // updates the second column to be 35 rs.updateBoolean(3, true); // updates the third column to true rs.insertRow(); rs.moveToCurrentRow();
```
```
```
A ResultSet object is automatically closed when the Statement object that generated it is closed or used to retrieve another result.
ResultSetMetaData object obtained through the ResultSet.getMetaData() method provides information about the ResultSet object's columns.

ResultSet Objects

A ResultSet object stores the results of a database query.
The cursor starts before the first row and moves one row at a time with the next() method.
Default ResultSet objects are not updatable and can only be traversed once.
The createStatement method can be used to create a scrollable and updatable ResultSet object.

Retrieving Data

Getter methods from the ResultSet interface retrieve column values from the current row.
Use either the column index (starting from 1) or column name to access data.
Column index access is typically more efficient.
Getter methods attempt to convert data types to the specified Java type.

Updating Data

The ResultSet interface provides updater methods for modifying data.
Update a column value in the current row using the update methods.
Scrollable ResultSet objects allow moving the cursor to specific rows using methods like absolute() and relative().
The updateRow() method applies changes to the underlying data source.
The insert row is a special staging area for building a new row.
Use moveToInsertRow() to access the insert row and update its column values.
The insertRow() method adds the row to the ResultSet and the data source.

Closing ResultSet Objects

ResultSet objects are automatically closed when the Statement object that generated them is closed, re-executed, or used to fetch another result.
Use the ResultSetMetaData object, retrieved through getMetaData(), to access column information like name, data type, and properties.

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Description

Explore the essential concepts of ResultSet objects in SQL, including their structure, cursor behavior, and methods for data retrieval. This quiz will guide you through the functionality of ResultSet in executing SQL queries and how to make them scrollable and updatable.

SQL ResultSet Objects Overview

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Questions and Answers

What is a characteristic of a default ResultSet object?

Which method can be used to advance the cursor in a ResultSet object?

Why is it recommended to read result set columns from left to right?

What happens when a getter method is called with a column name that appears multiple times in a result set?

What is the JDBC method to create a scrollable and updatable ResultSet?

How does a JDBC driver handle data type conversion for getter methods?

What is the default starting position of the cursor in a ResultSet object?

When using column names to retrieve values, how is case sensitivity handled?

What type of ResultSet can display changes made by other users?

What is the purpose of the SQL AS clause in relation to column names?

Which JDBC version introduced a set of updater methods to the interface?

How can a programmer update a column value in a ResultSet?

What does the moveToInsertRow method do in a ResultSet?

When is a ResultSet object automatically closed?

Which statement correctly describes the updater methods utilized in a ResultSet?

What is a necessary step before calling the updateRow method in a ResultSet?

Which method provides metadata about the columns of a ResultSet?

What is the first operation performed to insert a new row in a ResultSet?

Which of the following is NOT a function of the ResultSet object's updater methods?

A ResultSet object maintains a ______ pointing to its current row of data.

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

The ______ method is used to move the cursor to the next row in the ResultSet.

Column names used as input to getter methods are ______ insensitive.

Columns in a ResultSet are numbered starting from ______.

For maximum portability, result set columns should be read in ______-to-right order.

A JDBC driver attempts to convert the underlying data to the ______ type specified in the getter method.

When columns are not explicitly named in the query, it is best to use ______ numbers.

To create a scrollable ResultSet, the statement must include ______.

The JDBC specification provides a table showing the allowable mappings from SQL types to ______ types.

The programmer should ensure that column names uniquely refer to the intended columns using the SQL ______ clause.

In a scrollable ResultSet object, the cursor can be moved backwards and forwards to an ______ position.

The updateRow method is used to update the data source table from which the ResultSet object ______ was derived.

An updatable ResultSet object serves as a staging area for building a row to be ______.

The method moveToInsertRow moves the cursor to the ______ row.

A ResultSet object is automatically closed when the Statement object that generated it is ______.

The ______ object provides information about the number, types, and properties of a ResultSet object's columns.

The cursor must be moved to the insert row before calling the ______ method.

To update a column value in a ResultSet, the programmer uses specific ______ methods.

The first operation performed to insert a new row in a ResultSet involves moving the cursor to the ______ row.

Study Notes

ResultSet Object

ResultSet Objects

Retrieving Data

Updating Data

Closing ResultSet Objects

Studying That Suits You

Description

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