1. PROG11044 - Advanced Web Apps
4/13/2019
Programming Data Pages
Wendi Jollymore, ACES

2. Review So Far Classes we used: SqlConnection SqlCommand
A connection object that facilitates communication with the database
SqlCommand
A command object that models a specific SQL command to be executed over a specific connection
Connection property – references a connection object
CommandText property – contains the SQL command to execute
4/13/2019
Wendi Jollymore, ACES

3. Review So Far SqlDataReader A forward-only, read-only set of records
Returned by the command object’s ExecuteReader() method
command.ExecuteReader() executes the CommandText query over the Connection object
The resulting rows or records are returned as a Data Reader object
4/13/2019
Wendi Jollymore, ACES

4. Review So Far SqlDataReader, continued Read() method
Returns true if it read a record
Used to move through the records
reader[“fieldName”] syntax
Allows you to access the field values in the current record
4/13/2019
Wendi Jollymore, ACES

5. Review So Far SqlParameter
Some SQL statements will contain values that are dynamic
E.g. select * from authors where authorID = ?
The ? Value could come from a list box selection
Parameter objects are used to replace unknown or variable values
More secure than concatenating values together to build SQL statements
4/13/2019
Wendi Jollymore, ACES

6. The DataSet Object System.Data.DataSet
A virtual database
The client machine can download a copy of the tables/query results they want
DataSet data can be modified
You can move around in a data set
i.e. it’s not forward-only
The data set object can be used with any provider
4/13/2019
Wendi Jollymore, ACES

7. The DataSet Object A DataSet contains a collection of tables
It contains information about the tables, such as:
Schema
Records
Relationships
Constraints
4/13/2019
Wendi Jollymore, ACES

8. The DataSet Object DataSet.Tables property
References the collection of tables
This collection object is an instance of the DataTableCollection class
A DataTableCollection object contains a set of DataTable objects
Each DataTable object in the DataTableCollection is one of the tables in the database
4/13/2019
Wendi Jollymore, ACES

9. The DataSet Object Ways to reference a table in the dataset:
dataSet.Tables[“Books”]
dataSet.Tables[0]
4/13/2019
Wendi Jollymore, ACES

10. The DataTable Object Models a table from the database
dataTable.Rows property
References the DataRowCollection object
A collection of DataRow objects
The set of rows (records) in the table
4/13/2019
Wendi Jollymore, ACES

11. The DataTable Object dataTable.TableName property
The name you gave the table when you added it to the data set
dataTable.Columns property
References the DataColumnCollection object
A collection of DataColumn object
The set of columns (fields) in the table
dataTable.Columns.Count property
The number of columns in the table
4/13/2019
Wendi Jollymore, ACES

12. The DataRow Object
Models a row (record) in the row collection of the table
dataTable.Rows.Count property
The number of DataRow objects in the DataRowCollection
i.e. the number of records
dataTable.Rows.Find(keyValue)
Used to locate a specific record in the collection
keyValue is the value for the primary key field to match
4/13/2019
Wendi Jollymore, ACES

13. The SqlDataAdapter Object
A data adapter facillitates communication between the DataSet and the data source
DataSet is not provider specific
Everything else is
The data adapter will pass any data from the data source to the DataSet
The data adapter will also handle the data manipulation for you
4/13/2019
Wendi Jollymore, ACES

14. The SqlDataAdapter Object
SelectCommand property
Contains a command object that contains a SELECT query
UpdateCommand, DeleteCommand, InsertCommand properties
Contains command objects for UPDATE, DELETE, and INSERT commands
Command objects have their own connection, so that connection is used to execute the various commands
4/13/2019
Wendi Jollymore, ACES

15. The SqlDataAdapter Object
dataAdapter.Fill(dataSet) method
Executes the query in the SelectCommand property’s command object
Fills the dataset with the results of that query
dataAdapter.Fill(dataSet, strName)
As above but assigns the result table with strName as a table name
Accessed via dataSet.Tables[strName]
4/13/2019
Wendi Jollymore, ACES

16. Exercise ADO Notes: “Advanced Programming”
Do the tutorial “Working with the DataSet”
Do the “Multiple Tables in a DataSet” tutorial and exercise
4/13/2019
Wendi Jollymore, ACES

17. Iterating Through Records
There are a few ways you can iterate through the collection of data rows (records)
The rows collection can be used to access records and field values:
Get the third row:
DataRow aRow = dataSet.Tables[“Authors”].Rows[3];
Get the last name field value from the 1st row:
String lastName = aRow[“lastName”];
String lastName = dataSet.Tables[“Authors”].Rows[3][“lastName”];
4/13/2019
Wendi Jollymore, ACES

18. Iterating Through Records
dataRow.ItemArray property
References the field values in a row as an array of generic objects
You can retrieve this array and then iterate through it:
object[] values =
dataSet.Tables[“Books"].Rows[rowIndex].ItemArray;
for (int i=0; i<values.Length; i++) {
string output += values[i].ToString(); }
4/13/2019
Wendi Jollymore, ACES

19. Exercise
Try the two exercises in the section “Displaying Records Programmatically”
Do the “Navigating Records” exercise
4/13/2019
Wendi Jollymore, ACES