Download NET Data Access

.NET Data Access
台南市教育局網路中心
在職教師校務行政系統程式開發
進階班
行政網路組
[email protected]
Design Goals for ADO.NET
• Leverage Current ADO Knowledge
• Support the N-Tier Programming Model
• Integrate XML Support
Why ADO.NET?
ADO vs. ADO.NET
•
• ADO.NET
ADO
– Disconnected access
– Connected access
– Logical data model
– Physical data model
– The DataSet based data
– RecordSet based data
– DataSet is multi-table
– RecordSet is ‘one’ table
• > 1 table or source does
• > 1 table requires a
not require a JOIN
database JOIN
• Relationships remain:
• Data is “flattened”: lose
navigation is relational
relationships
– XML schema Data types
– COM/COM+ data types
– No data type conversions required
– Data via COM marshalling
– XML is plaintext: ‘Firewall
– Blocked by firewalls
friendly’
(DCOM, binary)
ADO.NET Architecture()
System.Data
DataSet
System.Data.SqlClient
System.Data.OleDb
.NET Data Providers
System.Data.SQLTypes
ADO.NET Architecture(2)
• XML and ADO.NET
• ADO.NET Components
.NET Data Provider
•
•
•
Retrieve data from a data source and
reconcile changes made to it with the data
source
The link between data source and
application
Two Providers out of the box:
– .NET SQL Data Provider: SqlClient
– .NET OLE DB Data Provider: OleDb
ADO.NET Data Provider
Core Classes
System.Data.<Provider>
Connection
Connect to data source
Command
Execute Command
against data source
Data Reader
Reads a forward-only readonly stream of data from a
data source
Data Adapter
Populates a DataSet and
resolves updates with data
source
Connection Class
•
•
•
•
Represent a unique session with a data source
Create, open, close a connection to a data source
Functionality and methods to perform transactions
Connection example:
String conStr = "Provider=Microsoft.Jet.OLEDB.4.0;" +
"Data Source=NWIND_RW.MDB";
OleDbConnection aConn = new OleDbConnection(conStr);
aConn.Open();
// Execute Queries using OleDbCommand Class
aConn.Close();
Connection
• OleDbConnection
Provider=MSDAORA; Data Source=ORACLE8i7; User ID=OLEDB; Password=OLEDB
Provider=Microsoft.Jet.OLEDB.4.0; Data Source=c:\bin\LocalAccess40.mdb;
Provider=SQLOLEDB;Data Source=MySQLServer;Integrated Security=SSPI;
• SqlConnection
user id=sa;password=aU98rrx2;initial catalog=northwind;data source=mySQLServer;Connect Timeout=30
Command Class
•
•
Represents a query to execute on the data
source
Methods of interest:
– ExecuteNonQuery: Executes a SQL statement
that doesn’t return any rows
– ExecuteReader: Returns a DataReader
– ExecuteScalar: Executes the query and returns
the first column of the first row
String SqlStr = “INSERT INTO Customers (CustId,FName,Lname) ;” +
“Values (‘Matt’,’Stephen’)”;
SqlCommand myCommand = new SqlCommand(SqlStr , myConnection);
myCommand.Connection.Open();
myCommand.ExecuteNonQuery();
myConnection.Close();
DataAdapter Class
•
•
•
Bridge between the DataSet and the data store
Means to modify the DataSet and data source
Properties of Interest: DeleteCommand, InsertCommand,
SelectCommand, UpdateCommand
•
•
TableMappings: Maps source and DataTable
Inherits methods from DbDataAdapter class
–
–
public virtual int Fill(DataSet,”Tablename”);
public virtual int update(DataSet,”Tablename”);
Data Store
DataAdapter
DataSet
DataReader
•
•
Forward-only data access
“Lightweight” programming model
– Less overhead than using Command
•
•
•
Instantiated by the Command class Execute method
Ties up the Command until it is finished reading
Methods to retrieve data:
– By index and optionally column type: GetString, GetInt32,
and so on
– Read: Advances reader to next record
DataReader Sample
// Code for creating the Connection “Conn” not shown
String myQuery = “SELECT * FROM Customers”;
Conn.Open();
OleDbCommand myCmd = new OleDbCommand( myQuery, Conn );
// Declare the DataReader...
OleDbDataReader myDataReader;
// Instantiate the DataReader with ExecuteReader(...) ...
myDataReader = myCmd.ExecuteReader();
// Always call Read before accessing data.
while(myDataReader.Read())
{
Console.WriteLine(myDataReader.GetString(0));
}
// Always Close the reader and the connection when done
myDataReader.Close();
Conn.Close();
System.Data Principal Classes
System.Data
Contains the ‘main’ classes of
ADO.NET
DataSet
In-memory cache of database
DataTable
In-memory cache of database table
DataRow
Used to manipulate a row in a
DataTable
DataColumn
Used to define the columns in a
DataTable
DataRelation
Used to relate two DataTables to each
other
DataView
Used to create a view on a DataSet
System.Data: DataSet Overview
DataSet
Tables
DataTable
DataView
DataRow(s)
Relations
DataRelation
DataRelation
DataColumn
Constraint(s)
DataTable
DataTable
DataView
System.Data: DataSet
•
•
•
An in-memory cache of data from a data source via
DataAdapter
XML used to read and write data and schema
Common way to represent and manipulate data
–
–
•
Logical or physical representation of data, depending on:
–
–
•
Universal data container
Not just for use with databases
The query/result set
Whether DataTables and Relations exist
Designed to be disconnected from the data source
–
Connect, execute query, disconnect
System.Data: DataTable
•
•
•
•
May be mapped to a physical table in the data
source
Can be related to one another through
DataRelations
Optimistic concurrency / locking
Properties of Interest:
– Columns: Returns DataColumnCollection of
DataColumns
– Rows: Returns DataRow objects as a
DataRowCollection
– Constraints: Returns the table’s
ConstraintCollection
System.Data: DataSet & DataTable
•
Create a DataTable and add it to a DataSet
DataSet ds = new DataSet();
// Create DataTable object: “Customers”.
DataTable dt = new DataTable( “Customers” );
// Create and add columns to the table
// 1. Explicitly create and Add a DataColumn
DataColumn dc = new DataColumn( “CustID”, typeof(Int16) );
dt.Columns.Add( dc );
// 2. Implicitly Create and Add columns (DataColumn).
dt.Columns.Add( “First_Name”, typeof(String) );
dt.Columns.Add( “Last_Name”, typeof(String) );
// Add the DataTable object to the DataSet
ds.Tables.Add( dt );
如何存取資料庫
•
ADO .NET 資料存取模型
– 資料庫連線 (Connection)
• SqlConnection 與 OleDbConnection
– 執行 SQL 語法 (Commands)
• SqlCommand 與 OleDbCommand
–
–
–
ExecuteNonQuery (不傳回資料列)
ExecuteScalar (傳回單一列資料)
ExecuteReader (傳回多列資料)
– 取得資料
• DataReader
• DataAdapter 與 DataSet
如何使用資料庫連線
•
使用資料庫連線的步驟
–
建立資料庫連線物件
OleDbConnection
conn = new OleDbConnection() ;
–
設定連線字串
conn.ConnectionString
=
"Provider=Microsoft.Jet.OLEDB.4.0;
User ID=Admin; Password=123;
Data Source=C:\Northwind.mdb" ;
–
–
–
開啟資料庫連線
conn.Open()
;
:
關閉資料庫連線
conn.Close()
;
Connection
•
•
SqlConnection
–
只能夠連接 Microsoft SQL
Server
conn.ConnectionString
=
–
–
"User
ID=sa; Password=;
效能最佳化
需引用 System.Data.SqlClient
Server=localhost;Database=Northwind" ;
OleDbConnection
––
–
–
–
可以透過 OLE DB 連接不同的資料庫
conn.ConnectionString
=
應用範圍最廣
"Provider=SQLOLEDB;
需引用 System.Data.OleDb
User ID=sa; Password=;
一樣可以連接
Microsoft SQL Server
Data
Source=localhost;
Initial Catalog=Northwind" ;
Command
•
SqlCommand 與 OleDbCommand
•
支援多種 SQL 命令
•
–
DCL : GRANT, REVOKE, DENY
–
DDL : CREATE, ALTER, DROP
–
DML : SELECT, INSERT, DELETE, UPDATE
–
其它 : Stored Procedure, CURSOR, …
允許加入參數 (Parameters)
執行 SQL 語法
•
執行非查詢式 SQL 語法
–
建立一個 Command
物件
SqlCommand
cmd = new
SqlCommand("update… where OrderID=@ID",
conn) ;
–
建立參數物件param = new
SqlParameter
SqlParameter("@ID", typeof(int)) ;
–
設定參數值 = 12 ;
param.Value
–
將參數加入 Command 物件 ;
cmd.Parameters.Add(param)
–
執行
SQL 語法= cmd.ExecuteNonQuery() ;
int
rowEffects
如何執行 SQL 語法
•
執行查詢式 (單筆記錄) SQL 語法
–
建立一個
string
sql =Command
"select cid 物件
from… where OrderID=@ID" ;
–
SqlCommand cmd = new SqlCommand(sql, conn) ;
–
建立參數物件param = new
SqlParameter
SqlParameter("@ID", typeof(int)) ;
–
設定參數值 = 12 ;
param.Value
–
將參數加入 Command 物件 ;
cmd.Parameters.Add(param)
–
執行
Command
int
myCID
= (int)並取得結果
cmd.ExecuteScalar() ;
如何處理多筆記錄
•
執行查詢式 (多筆記錄) SQL 語法
–
建立一個
物件 Qty from MyOrders" ;
string
sql =Command
"select PName,
–
SqlCommand cmd = new SqlCommand(sql, conn) ;
–
執行 Commanddr並取得
DataReader
SqlDataReader
= cmd.ExecuteReader()
;
–
讀取下一筆記錄
while
( dr.Read() )(如果 true 表示有資料)
{
取得第一個欄位
string
pname = dr.GetString(0) ;
取得第二個欄位
int
qty = dr.GetInt32(1) ;
Console.WriteLine("{0}, {1}", pname, qty) ;
}
如何執行 Stored Procedure
•
執行 Stored Procedure
–
建立一個 Command
物件SqlCommand() ;
SqlCommand
cmd = new
–
設定使用連線 = conn ;
cmd.Connection
–
設定命令名稱 = "DeleteOrder" ;
cmd.ComandText
–
設定 CommandType=
cmd.CommandType
CommandType.StoredProcedure ;
–
建立參數
cmd.Parameters.Add("@ID",
orderID) ;
–
執行
Stored Procedure
int
rowEffects
= cmd.ExecuteNonQuery() ;
Data Access Layer
Calling stored procedures
Dim sqlconn As SqlConnection = New SqlConnection(connectionstring)a
Dim sqlcomm As SqlCommand = New SqlCommand()
sqlcomm.CommandType = CommandType.StoredProcedure
sqlcomm.CommandText = "DemoProc“
‘Open Connection
sqlconn.Open()
sqlcomm.Connection = sqlconn
'Create parameters
sqlcomm.Parameters.Add(New SqlParameter("@input1", SqlDbType.Int))
sqlcomm.Parameters.Add(New SqlParameter("@input2", SqlDbType.Int))
sqlcomm.Parameters.Add(New SqlParameter("@output1",
SqlDbType.Int)).Direction = ParameterDirection.Output
‘Set Parameter Values
sqlcomm.Parameters.Item("@input1").Value = 123
sqlcomm.Parameters.Item("@input2").Value = 456
sqlcomm.ExecuteNonQuery()
‘Access Output
Response.write (sqlComm.Parameters.Item(“@output1”).Value.ToString())
WebForms 控制項資料繫結
<%@ Import Namespace="System.Data.SqlClient" %>
<html><head><script language="C#" runat=server>
public void Page_Load(Object sender, EventArgs args) {
// 建立資料庫連線，並取得 DataReader
SqlConnection cnn = new SqlConnection("server=localhost;uid=sa;");
conn.Open();
SqlCommand cmd = new SqlCommand("select * from customers", conn);
SqlDataReader dr = cmd.ExecuteReader();
// 將資料來源繫結到控制項
dgCustomers.DataSource = dr;
dgCustomers.DataBind();
}
</script></head><body>
<asp:DataGrid id="dgCustomers" runat="server"/>
</body></html>
自訂 Data Provider
• ADO .NET 共有那些 Data Provider
–
–
–
–
SQL Data Provider
OLE DB Data Provider
ODBC Data Provider (外掛)
Oracle Data Provider (未來)
DataAdapter 與 DataSet
•
DataSet 與資料庫之間透過 DataAdapter 進行
存取動作
DataAdapter
SelectCommand
 Fill 
資
料
庫
InsertCommand
 Update 
UpdateCommand
DeleteCommand
DataSet
如何取得 DataSet
•
透過 DataAdapter 取得 DataSet 資料
–
建立一個 Command
SqlCommand
cmd = new SqlCommand() ;
用來執行 SELECT
語法;
cmd.Connection
= conn
cmd.ComandTextda=="select
* from Customers" ;
– SqlDataAdapter
new SqlDataAdapter(
建立 DataAdapter
– SqlDataAdapter
da物件
= "select
new SqlDataAdapter()
; conn) ;
* from Customers",
–
設定 SelectCommand
da.SelectCommand
= cmd;
–
建立一個
物件
DataSet
dsDataSet
= new DataSet("Customers")
;
–
使用 DataAdapter
物件的 Fill 方法
da.Fill(ds)
;
填滿 DataSet
DataSet 的結構
•
透過欄位號碼或欄位名稱來存取
DataRow
(每一筆記錄)
中包含了多個欄位
DataRow
的資料
DataTable
使用
Tables[表格號碼]
可以包含多筆資料列
或 Tables["表格名稱"]
(Row)，組成
Rows
集合
DataSet
可以包含多個表格
(Table)，組成
Tables
集合
每一個
Rows
Rows[列號碼]
集合中的每一筆資料記錄都是一個
DataSet
中的表格都是一個
來引用
Tables
中的任何一個表格。
DataTable
DataRow
物件
物件
來引用
Tables可以取得資料總筆數)
中的任何一個表格。
(Rows.Count
(Tables.Count 可以取得表格數目)
DataSet
Tables[0]
DataTable
Tables[1]
Tables[2] DataRow
Rows[0]
Tables[3] Rows[1]
: 1 Rows[2] 2
Tables
0
3
: 性別 Rows
姓名
電話
血型
:
: 男
王小明
AB
: (04)2222-2222
:
:
DataRow: row = ds.Tables[0].Rows[3];
:
string name = row[0];
string phone = row["電話"];
如何瀏覽 DataSet 中的資料
for 迴圈瀏覽
DataSet
資料資料
• 使用 foreach
迴圈瀏覽
DataSet
for(int c=0;c < ds.Tables[0].Columns.Count;
foreach(DataRow
cust in ds.Tables[0].Rows) c++) {
{ DataColumn dc = ds.Tables[0].Columns[c] ;
Console.Write("{0}\t", dc.ColumnName)
;
Console.WriteLine("\n客戶:
{0}", cust["Name"]);
} foreach(DataRow ord in cust.GetChildRows("odr"))
for(int
{ r = 0;r < ds.Tables[0].Rows.Count;r++) {
string cName
= ds.Tables[0].Rows[r]["客戶名稱"]
Console.Write("訂單編號:
{0}", ord["id"]);;
string cAddress
= ds.Tables[0].Rows[r]["地址"]
;
Console.Write("\t數量:{1}\n",
ord["qty"]);
}Console.WriteLine("\n{0}\t{1}", cName, cAddress) ;
}
Data, XML, And .NET
XML Recap
•
•
•
•
•
•
XML declaration
Document element
<?xml version="1.0"?>
Elements
<employees xmlns="urn:…">
Attributes
<employee id="123">
Text content
<name>Philips</name>
<salary>145000</salary>
Namespaces
</employee>
…
</employees>
.NET XML Classes
Namespaces and Classes
System.Xml namespace
•
XmlReader
XmlDocument
XmlWriter
XmlElement
XmlNavigator
XmlAttribute
etc.
Plus…
System.Xml.XPath
XPath engine
System.Xml.Xsl
XSLT transforms
.NET XML Classes
Reading XML Data
• Use XmlReader class
– Fast, forwards-only, read-only cursor
– “Pull” model (not the “push” model of SAX)
• XmlReader is an
abstract class
XmlReader
{ Abstract class }
– Several concrete
subclasses
XmlTextReader
XmlNodeReader
Read a text-based
stream
Read an in-memory
DOM tree
.NET XML Classes
Using XmlReader
• Example
XmlReader reader;
reader = new XmlTextReader("MyFile.xml");
while(reader.Read())
{ …process nodes… }
• Capabilities
– Pull nodes you want, skip those you don't
– Get detailed node information
– Get typed data
.NET XML Classes
Writing XML Data
XmlWriter
•
Use XmlWriter
XmlTextWriter
XmlNodeWriter
XmlWriter writer = new XmlTextWriter(…);
writer.WriteStartDocument();
writer.WriteStartElement("name", "Mike");
•
Alternatively…
– Create content using XmlDocument
– Serialise data using XmlWriter
.NET XML Classes
Using XPath
•
•
XPath maps an XML document
to a tree of nodes
Use XPath expressions to identify, select, and
manipulate nodes
in an XML hierarchy
– Use location paths
to select nodes
– XPath operators and functions
.NET XML Classes
XML .NET Support for XPath
•
XmlNavigator class provides XPath
support
XmlNavigator nav;
nav = new DocumentNavigator(document);
•
Evaluate XPath expressions
nav.Evaluate("count(//employee)");
•
Select nodes using XPath
nav.Select("//employee[salary > 75000]");
.NET XML Classes
Using XSLT
XML
document
XSLT
processor
+
HTML document
(XML-conformant)
XSLT
style sheet
XML
document
+
XSLT
style sheet
XSLT
processor
XML document
(different grammar)
.NET XML Classes
XML .NET Support for XSLT
•
XslTransform class represents an XSLT
style sheet
// Load style sheet
XslTransform xsl = new XslTransform();
xsl.Load("MyStylesheet.xsl");
// Perform transformation
xsl.Transform(aNavigator,
null,
anXmlWriter);
XML and ADO.NET
Unified Architecture
Controls,
Designers,
Code-gen, etc.
XSL/T, X-Path,
Validation, etc.
XmlDataDocument
XmlReader
XmlTextReader
XmlNodeReader
DataSet
Sync
DataAdapter
SqlData- OleDbDataAdapter
Adapter
DataReader
SqlData- OleDbDataReader
Reader