6 处理关联的非连接数据

6.1 导航关系

 

代码

' 使用DataRelation对象在DataRow父子对象之间实现双向导航    
         Dim  ds1  As   New  DataSet

         ' create tables
         Dim  dt1  As  DataTable  =  ds1.Tables.Add( " dt1 " )
         Dim  dt2  As  DataTable  =  ds1.Tables.Add( " dt2 " )

         ' create columns
         Dim  parentPk  As  DataColumn  =  dt1.Columns.Add( " pk " ,  GetType ( Integer ))
        dt2.Columns.Add( " pk " ,  GetType ( Integer ))
         Dim  childFk  As  DataColumn  =  dt2.Columns.Add( "F k " ,  GetType ( Integer ))

         ' create relation
         Dim  rel  As  DataRelation  =   New  DataRelation( " dt1dt2 " , parentPk, childFk)
        ds1.Relations.Add(rel)

         ' add some data
        dt1.Rows.Add( 1 )
        dt1.Rows.Add( 2 )
        dt1.Rows.Add( 3 )
        dt1.Rows.Add( 4 )
        dt1.Rows.Add( 5 )

        dt2.Rows.Add( 1 ,  1 )
        dt2.Rows.Add( 2 ,  1 )
        dt2.Rows.Add( 3 ,  2 )
        dt2.Rows.Add( 4 ,  2 )
        dt2.Rows.Add( 5 ,  2 )

         ' get a parent row
         Dim  parentRow  As  DataRow  =  dt1.Rows( 1 )
         ' get children
         Dim  children  As  DataRow()  =  parentRow.GetChildRows(rel)
         ' get parent again
         Dim  myParent  As  DataRow  =  children( 0 ).GetParentRow(rel)

 

6.2 创建约束

6.3 更新数据：引入访问层

6.3.1 获取关系

 

代码

IF   EXISTS (
     SELECT   *   FROM  dbo.sysobjects
     WHERE  id = OBJECT_ID ( ' dbo.uspGetSqlRelationships ' ) 
     AND   OBJECTPROPERTY (id, ' IsProcedure ' ) = 1 )
     DROP   PROCEDURE  dbo.uspGetSqlRelationships
CREATE   PROCEDURE  dbo.uspGetSqlRelationships
AS
     IF   OBJECT_ID ( ' tempdb..#temp ' ) IS   NOT   NULL   DROP   TABLE  # temp
     SELECT  r_obj.name  as  relationshipName,
        parent_obj.name  as  Parent,
        child_obj.name  as  child,
         CONVERT ( nvarchar ( 1000 ), '' )  as  pk,
         CONVERT ( nvarchar ( 1000 ), '' )  as  fk,
        r.fkeyid,
        r.rkeyid,
        r.constid
     INTO  # temp  
     FROM  dbo.sysobjects r_obj
         INNER   JOIN  dbo.sysreferences r  ON  r_obj.id = r.constid
         INNER   JOIN  dbo.sysobjects parent_obj  ON  r.rkeyid = parent_obj.Id
         INNER   JOIN  dbo.sysobjects child_obj  ON  r_obj.parent_obj = child_obj.Id
         INNER   JOIN  dbo.sysforeignkeys fkeys  ON  fkeys.constid = r.constid
         INNER   JOIN  dbo.syscolumns cols  ON  cols.id = fkeys.fkeyid  and  cols.colid = fkeys.fkey
     WHERE  r_obj.xtype = ' F '   AND  (r_obj.status  &   0x100 ) = 0
        
     DECLARE   @PK   VARCHAR ( 1000 ),  @FK   VARCHAR ( 1000 )
     DECLARE   @fkeyid   int , @rkeyid   int ,  @cnstid   INT
     DECLARE   @keys   NVARCHAR ( 2126 )
     DECLARE   @cnstname  SYSNAME
     DECLARE   @cnstdes   nvarchar ( 4000 )
     DECLARE   @cnsttype   CHARACTER ( 2 )
     DECLARE   @relName   VARCHAR ( 1000 )
    
     DECLARE  tempTable  CURSOR  LOCAL  FOR
         SELECT  relationshipName,pk,fk,fkeyid,rkeyid,constid  FROM  # temp
     open  tempTable
     FETCH  tempTable  into   @relName , @pk , @fk , @fkeyid , @rkeyid , @constid  
    
     WHILE   @@FETCH_STATUS >= 0
     BEGIN
         DECLARE  ms_crs_fkey  cursor  local  FOR
             SELECT  fkey,rkey  from  sysforeignkeys  WHERE  constid = @cnstid
         OPEN  ms_crs_fkey
         FETCH  ms_crs_fkey  into   @fkey , @rkey
        
         SELECT   @keys = col_name ( @fkeyid , @fkeycol )
         SELECT   @cnstdes = col_name ( @rkeyid , @rkeycol )
        
         FETCH  ms_crs_fkey  into   @fkey , @rkey
         WHILE   @@FETCH_STATUS >= 0
         BEGIN
             SELECT   @keys = @keys + ' , ' + col_name ( @fkeyid , @fkeycol )
             SELECT   @cnstdes = @cnstdes + ' , ' + col_name ( @rkeyid , @rkeycol )
             FETCH  ms_crs_fkey  into   @fkey , @rkey
         END
         DEALLOCATE  ms_crs_fkey
         UPDATE  # temp
         SET  pk = @cnstdes ,fk = @keys
         WHERE  relationshipName = @relName
         FETCH  tempTable  into   @relName , @pk , @fk , @fkeyid , @rkeyid , @constid  
     END
     DEALLOCATE  tempTable
     SELECT   DISTINCT  relationshipName, Parent, child,pk,fk  from  # temp

 

 

6.3.2 获取表列

 

代码

IF   EXISTS (
     SELECT   *   FROM  dbo.sysobjects
     WHERE  id = OBJECT_ID ( ' dbo.uspGetSqlTables ' ) 
     AND   OBJECTPROPERTY (id, ' IsProcedure ' ) = 1 )
     DROP   PROCEDURE  dbo.uspGetSqlTables
CREATE   PROCEDURE  dbo.uspGetSqlTables
AS
     SELECT  TABLE_NAME
     FROM  information_schema.TABLES
     WHERE  table_type = ' BASE TABLE '  
         and  TABLE_NAME <> ' dtproperties '
         and  TABLE_NAME <> ' sysdiagrams '

 

 

6.3.3 排序表列

 

代码

Imports  System.Configuration
Imports  System.Data.Common
Imports  System.Data.SqlClient
Imports  System.Text

Public   Class  DataAccess
     Public   Shared   Property  Instance()  As  DataAccess
         Get
             Return  _instance
         End   Get
         Set ( ByVal  value  As  DataAccess)
            _instance  =  value
         End   Set
     End Property
     Private   Shared  _instance  As  DataAccess

     Public   Property  OrderedTableList()  As  DataTable
         Get
             Return  _orderedTableList
         End   Get
         Set ( ByVal  value  As  DataTable)
            _orderedTableList  =  value
         End   Set
     End Property
     Private  _orderedTableList  As  DataTable

     Private   Sub  BuildOrderedTableList()
         Dim  sourceTableList  As  DataTable  =  GetTable( " dbo.uspGetSqlTables " )
         Dim  sourceRelationList  As  DataTable  =  GetTable( " dbo.uspGetSqlRelationships " )
        OrderedTableList  =  sourceTableList.Clone
        OrderedTableList.TableName  =   " OrderedTableList "

         Dim  iCounter  As   Integer   =   0
         While  iCounter  <  sourceRelationList.Rows.Count
             If  sourceRelationList.Rows(iCounter)( " child " ).ToString  =  _
                sourceRelationList.Rows(iCounter)( " parent " ).ToString  Then
                sourceRelationList.Rows.Remove(sourceRelationList.Rows(iCounter))
             Else
                iCounter  +=   1
             End   If
         End   While

         Dim  position  As   Integer   =   0
         Dim  lastCount  As   Integer   =  sourceTableList.Rows.Count
         While  sourceTableList.Rows.Count  <>   0
             Dim  findChild  As   String   =   String .Format( " [child]='{0}' " , sourceTableList.Rows(position)( " TABLE_NAME " ))
             If  sourceRelationList.Select(findChild).Length  =   0   Then
                 Dim  findParent  As   String   =   String .Format( " [parent]='{0}' " , sourceTableList.Rows(position)( " TABLE_NAME " ))
                 For   Each  parent  As  DataRow  In  sourceRelationList.Select(findParent)
                    sourceRelationList.Rows.Remove(parent)
                 Next

                OrderedTableList.Rows.Add(sourceTableList.Rows(position).ItemArray)
                sourceTableList.Rows.RemoveAt(position)
                position  =   0
             Else
                position  +=   1
                 If  position  =  sourceTableList.Rows.Count  Then
                    FindCircularErrors(sourceRelationList)
                 End   If
                lastCount  =  sourceTableList.Rows.Count
                position  =   0
             End   If
         End   While
     End Sub

     Private   Sub  FindCircularErrors( ByVal  sourceRelationList  As  DataTable)
         For   Each  currentRelation  As  DataRow  In  sourceRelationList.Rows
             Dim  beenThere  As   New  ArrayList
             If  IsCircular(currentRelation, beenThere, sourceRelationList)  Then
                 Dim  pathBuilder  As   New  StringBuilder
                 For   Each  relation  As  DataRow  In  beenThere
                    pathBuilder.AppendFormat( " parent: {0,-35} child:{1,-35} Relationship:{2} "   &  vbCrLf, _
                        relation( " parent " ), relation( " child " ), relation( " child " ), relation( " relationshipName " ))
                 Next
                 Throw   New  InvalidConstraintException( " Circular relationships exist in the database. "   &  vbCrLf  &  pathBuilder.ToString)
             End   If
         Next
     End Sub

     Private   Function  IsCircular( ByVal  currentRelation  As  DataRow,  ByVal  beenThere  As  ArrayList,  ByVal  relations  As  DataTable)  As   Boolean
        beenThere.Add(currentRelation)
         For   Each  childRelation  As  DataRow  In  relations.Rows
             If  childRelation( " Parent " ).ToString  =  currentRelation( " child " ).ToString  Then
                 If  beenThere.Contains(childRelation)  Then   Return   True
                 Dim  currentPath  As   New  ArrayList(beenThere)
                 If  IsCircular(childRelation, currentPath, relations)  Then
                    beenThere  =  currentPath
                     Return   True
                 End   If
             End   If
         Next
         Return   False
     End Function

     Public   Shared   Function  GetTable( ByVal  storedProcedure  As   String )  As  DataTable
         Dim  cnString  As  ConnectionStringSettings
        cnString  =  ConfigurationManager.ConnectionStrings( " CustomerData " )
         Dim  dt  As   New  DataTable
         Using  connection  As  DbConnection  =   New  SqlConnection
            connection.ConnectionString  =  cnString.ConnectionString
             Dim  cmd  As  DbCommand  =  connection.CreateCommand
            cmd.CommandType  =  CommandType.StoredProcedure
            cmd.CommandText  =  storedProcedure
            connection.Open()
            dt.Load(cmd.ExecuteReader)
         End   Using
         Return  dt
     End Function
End Class

 

 

 

调用方法

 

代码

Private   Sub  btnGetOrderedTables_Click( ByVal  sender  As  System.Object,  ByVal  e  As  System.EventArgs)  Handles  btnGetOrderedTables.Click
    DataGridView1.DataSource  =  DataAccess.Instance.OrderedTableList
End Sub

 

 

6.3.4 使用OrderedTableList对象执行更新操作

在DataAccess中添加BuildList

代码

     Public   Function  BuildList( ByVal  state  As  DataRowState,  ByVal  ds  As  DataSet)  As  ArrayList
         Dim  list  As   New  ArrayList

         For   Each  drTable  As  DataRow  In  OrderedTableList.Rows
             Dim  s  As   String   =   CType (drTable( " TABLE_NAME " ),  String )
             Dim  dt  As  DataTable  =  ds.Tables(s)
             If   Not  dt  Is   Nothing   Then
                list.Add(dt)
             End   If
         Next

         If  state  =  DataRowState.Deleted  Then
            list.Reverse()
         End   If

         Return  list
     End Function

 

创建DataAccess类的Update

代码

     Public   ReadOnly   Property  TableAdapterMappings()  As  Dictionary( Of   String , TableAdapterBase)
         Get
             Return  _tableAdapterMappings
         End   Get
     End Property
     Private  _tableAdapterMappings  As   New  Dictionary( Of   String , TableAdapterBase)

     Public   Sub  Update( ByVal  ds  As  DataSet)
        UpdateOperation(ds, DataRowState.Added)
        UpdateOperation(ds, DataRowState.Modified)
        UpdateOperation(ds, DataRowState.Deleted)
     End Sub

     Public   Sub  UpdateOperation( ByVal  ds  As  DataSet,  ByVal  state  As  DataRowState)
         Dim  _buildList  As  ArrayList  =  BuildList(state, ds)
         For   Each  table  As  DataTable  In  _buildList
             Using  tempTable  As  DataTable  =  table.GetChanges(state)
                 If   Not  tempTable  Is   Nothing   Then
                     Dim  ta  As  TableAdapterBase  =  TableAdapterMappings(table.TableName)
                    ta.UpdateTable(tempTable)
                 End   If
             End   Using
         Next
     End Sub

 

TableAdapterBase的实现代码

 

代码

Imports  System.Data.Common
Imports  System.Reflection

Partial   Public   MustInherit   Class  TableAdapterBase
     Inherits  System.ComponentModel.Component

     Public   Sub   New ()
        ContinueUpdateOnError  =   True
         For   Each  tableMapping  As  DataTableMapping  In  ChildAdapter.TableMappings
            DataAccess.Instance.TableAdapterMappings(tableMapping.DataSetTable)  =   Me
         Next
     End Sub

     ReadOnly   Property  ChildAdapter()  As  DbDataAdapter
         Get
             Dim  myAdapter  As  PropertyInfo  =   Me .GetType.GetProperty( " Adapter " , _
                Reflection.BindingFlags.GetProperty  Or  BindingFlags.NonPublic  Or  BindingFlags.Instance)
             Return   CType (myAdapter.GetValue( Me ,  Nothing ), DbDataAdapter)
         End   Get
     End Property

     Property  ContinueUpdateOnError()  As   Boolean
         Get
             Return  ChildAdapter.ContinueUpdateOnError
         End   Get
         Set ( ByVal  value  As   Boolean )
            ChildAdapter.ContinueUpdateOnError  =  value
         End   Set
     End Property
     Public   Function  UpdateTable( ByVal  table  As  DataTable)  As   Integer
         Return  ChildAdapter.Update(table)
     End Function
End Class

  

6.3.5 测试关联更新

 

代码

     Private  custDataSet  As   New  CustomerDataSet

     Private   Sub  btnUpdate_Click( ByVal  sender  As  System.Object,  ByVal  e  As  System.EventArgs)  Handles  btnUpdate.Click
         Dim  Adapter  As  TableAdapterBase
        Adapter  =   New  CustomerDataSetTableAdapters.TblProductTableAdapter
        Adapter  =   New  CustomerDataSetTableAdapters.TblSalesPersonTableAdapter
        Adapter  =   New  CustomerDataSetTableAdapters.TblCustomerTableAdapter
        Adapter  =   New  CustomerDataSetTableAdapters.TblLocationTableAdapter
        Adapter  =   New  CustomerDataSetTableAdapters.TblOrderTableAdapter
        Adapter  =   New  CustomerDataSetTableAdapters.TblOrderItemTableAdapter

         Dim  p1Id  As  Guid  =  Guid.NewGuid
         Dim  p2Id  As  Guid  =  Guid.NewGuid
         Dim  spId  As  Guid  =  Guid.NewGuid

         Dim  cId  As  Guid  =  Guid.NewGuid
         Dim  l1Id  As  Guid  =  Guid.NewGuid
         Dim  l2Id  As  Guid  =  Guid.NewGuid

         Dim  oId  As  Guid  =  Guid.NewGuid
         Dim  oi1Id  As  Guid  =  Guid.NewGuid
         Dim  oi2Id  As  Guid  =  Guid.NewGuid

         With  custDataSet
             With  .TblProduct
                .LoadDataRow( New   Object () {p1Id,  " Widget 1 " ,  123.45 },  False )
                .LoadDataRow( New   Object () {p2Id,  " Widget 2 " ,  234.56 },  False )
             End   With

            .TblSalesPerson.LoadDataRow( New   Object () {spId,  " Joe " },  False )

            .TblCustomer.LoadDataRow( New   Object () {cId, spId,  " Joe's Customer " },  False )

             With  .TblLocation
                .LoadDataRow( New   Object () { _
                             l1Id, cId,  " HQ " ,  " add1 " ,  " add2 " ,  " city " ,  " State " ,  " 12345 " ,  " US " },  False )
                .LoadDataRow( New   Object () { _
                             l2Id, cId,  " WAREHOUSE " ,  " add1 " ,  " add2 " ,  " city " ,  " State " ,  " 12345 " ,  " US " },  False )
             End   With

            .TblOrder.LoadDataRow( New   Object () {oId, cId,  " 1 " , l2Id, l1Id},  False )

             With  .TblOrderItem
                .LoadDataRow( New   Object () {oi1Id, oId, p1Id,  1 ,  " Widget1 " ,  1 ,  123.45 },  False )
                .LoadDataRow( New   Object () {oi2Id, oId, p2Id,  2 ,  " Widget2 " ,  2 ,  234.56 },  False )
             End   With
         End   With

        DataAccess.Instance.Update(custDataSet)
        MessageBox.Show( " Customer Database Updated " )
     End Sub