Lesson 1 DataSet

Chapter 3 Binding, linking, update data in a disconnected environment Lesson 1: DataSet  What is DataSet?  Differences between DataSet and DataReader  DataSet structure  Creating DataSet objects  Display data to controls from DataSet Contents Slide 2  DataSet object  is a major component of the ADO.NET architecture  is an in-memory cache of data retrieved from a data source  can include tables, relationships, and both unique and foreign key constraints  DataSet  a relational database in memory  working with data in a disconnected environment What is DataSet? Slide 3  To manipulate the data without an open connection  To perform database modifications  To bind data  To transfer data between tiers have .NET framework (Linux, Unix, Windows…)  To send between computers across network by HTTP protocol in XML format  Power data structure  Event an application without database, we can using dataset instead of arraylist, array… Why DataSet? Slide 4 DataReader DataSet Connected Disconnected Does not support data binding Support data binding Access data in forward-only Access data in any direction Data is read-only Supports data updates No support for sorting and filtering Data can be easily sorted and filtered DataReader - DataSet: main differences Slide 5  Two kinds of DataSet: untyped and typed  Untyped-Dataset: from generic type  Typed-Dataset: from schema (.xsd)  Two ways to create DataSet  By programmatically : for untyped-Dataset (see next)  By using design-time tools (the DataSet Designer and the Data Source Configuration Wizard) : for typed-Dataset  Homework: Module 11 Creating DataSet objects Slide 6 DataSet structure DataSet DataTable Collection DataTable DataRowCollection DataColumnCollection ParentRelations ChildRelations ConstraintCollection DataView DataRelationCollection Slide 7  DataTable represents one table in DataSet  To add a DataTable to DataSet:  dataset.Tables.Add(DataTable tbl)  To access a table in a DataSet:  Using index : dataset.Tables[0]  Using name: dataset.Tables[“authors”]  To access to data-cell  table.Rows[rowindex][colindex]  Properties of DataTable:  Columns property  Rows property  DefaultView  PrimaryKey property DataTable structure DataSet DataTable DataRow DataColumn DataTable DataRow DataColumn Slide 8  DataColumn describes one column of data in a DataTable  Get a column of a table:  table.Columns[index]  table.Columns[“colName”]  Some properties, methods  ColumnName  DataType  AllowDBNull  AutoIncrement  DefaultValue DataColumn structure DataSet DataTable DataRow DataColumn DataTable DataRow DataColumn Slide 9  A DataRow contains the data of a row in the DataTable  Create a DataRow  table.NewRow()  Delete a DataRow  datarow.Delete()  Get a row of a table:  table.Rows[index]  table.Rows[“colName”]  Visit all rows in a table:  foreach (DataRow dr in table.Rows) { …} DataRow structure DataSet DataTable DataRow DataColumn DataTable DataRow DataColumn Slide 10 [...]... DataColumn childColumn); parentDatatable.Constraints.Add(fk); Slide 12 Add a relationship between tables within a DataSet  DataRelation Slide 13 Example 1: Create a dataset with one table // 1a Create a DataSet object DataSet dataset = new DataSet( ); // 1b Add DataTable(s) DataTable tableLop = new DataTable("Lop"); dataset. Tables.Add(tableLop); // 1c Add columns to a Data Table tableLop.Columns.Add("MaLop",...Creating DataSet objects  Populating DataSet manually 1 Construct your own DataSet (schema) a b c d 2 Create DataSet Add DataTable(s) Add DataColumn(s) to DataTable Add constraints to DataTable Fill data into DataTable(s) in DataSet a b Add DataRow to DataTable Processing data in dataset … Slide 11 Add constraints to a DataTable  Primary constraint datatable.PrimaryKey... typeof(int)); // 1d Create a primary key for a DataTable object tableLop.PrimaryKey = new DataColumn[]{ tableLop.Columns["MaLop"] }; // 2a Add rows to a DataTable DataRow dr = tableLop.NewRow(); dr["MaLop"] = "TH99"; dr["TenLop"] = "Tin hoc 99"; dr["SiSo"] = 10 0; tableLop.Rows.Add (dr); Slide 14 Example 2: Create a dataset with tables DataSet dataset = new DataSet( ); DataTable tableLop, tableSV; dataset. Tables.Add(... tableLop.Columns["MaLop"], tableSV.Columns["MaLop"]); tableLop.Constraints.Add(fk); Slide 15 Display data to controls from DataSet  Get table in dataset and process…  foreach( DataRow dr in dataset. Tables["tableName"].Rows ) { // do something with DataRow dr } Example: display tableSV to ListView private void HienLenListView( DataSet ds, ListView lvw ) { lvw.Items.Clear(); foreach ( DataRow dr in ds.Tables["SinhVien"].Rows... dr["HoTen"].ToString() ); li.SubItems.Add( dr["MaLop"].ToString() ); } } Slide 16  You can use the IsNull method of the DataRow class to test for null values from a database Slide 17 Quick check    How do you add a DataTables to a DataSet? How do you retrieve a DataTable from a DataSet? How do you add data to a DataTable? Slide 18 Lab: with DataTable  Lab: Create a DataTable, p.353, with notes:  ... DataAdapter retrieves data into a DataSet from a data source by using the Fill method  Example: OleDbCommand cmd = new OleDbCommand(); cmd.CommandType = CommandType.Text; cmd.CommandText = "select * from danhba"; cmd.Connection = conn; // opened connection DataSet ds = new DataSet( ); OleDbDataAdapter da = new OleDbDataAdapter(cmd); da.Fill(ds, "DanhBa"); // process dataset, see next… Slide 30 Update... represents a set of SQL commands and a database connection that are used to fill the DataSet and update the data source   The DataAdapter serves as a bridge between a DataSet and a data source for retrieving and saving data How to use DataAdapter with data providers? Database Connection Windows Form Command DataAdapter DataSet Slide Disconnected 28 Create DataAdapter object  Create DataAdapter object:... DataTable, p.377, with notes:  Use RejectChanges and AcceptChanges method Slide 19 Chapter 3 Binding, linking, update data in a disconnected environment Lesson 2: DataAdapter Connected & Disconnected environment  Two ways access data using with ADO.NET Connected DataReader Database Connection Windows Form Command DataAdapter DataSet Disconnected Slide 25 Disconnected data access Advantages    Single... OleDbCommandBuilder cmd = new OleDbCommandBuilder(da);  Demo  Update change to database from dataset Slide 33 Update data using DataAdapter (cont.) Demo Module 12 -3  Example: add a new row into DanhBa table OleDbCommand cmd = new OleDbCommand(); cmd.CommandType = CommandType.Text; cmd.CommandText = "select * from danhba where 1= 2"; // chỉ lấy cấu trúc cmd.Connection = conn; OleDbDataAdapter da = new OleDbDataAdapter(cmd);... OleDbDataAdapter(cmd); da.Fill(ds, "DanhBa"); // process dataset, see next… Slide 30 Update data using DataAdapter (p.359)   Using the Update method of the DataAdapter to submit any changes made to the DataSet back to the data source To do that, the DataAdapter must have DataAdapter commands: DeleteCommand, InsertCommand, UpdateCommand   When Update method is called, the DataAdapter analyzes the changes