DataSet中表的关系及约束

using System;

using System.Collections.Generic;

using System.Text;

using System.Data;

namespace ConsoleApplication1.DataSetRelationsConstraints

{

/// <summary>

/// DataSet中表的数据关系及约束

/// </summary>

public class DataSetRelationsConstraintsBO

{

DataSet ds = new DataSet("Relationships");

//----------------------------------------------------------------------------------------------------------------------------

/// <summary>

/// 构造函数

/// </summary>

public DataSetRelationsConstraintsBO()

{

ds.Tables.Add(CreateBuildingTable());

ds.Tables.Add(CreateRoomTable());

Console.WriteLine("构造数据成功：");

ShowDataSet();

}

//----------------------------------------------------------------------------------------------------------------------------

/// <summary>

/// 测试

/// </summary>

public static void TestDataSetRelationsConstraints()

{

DataSetRelationsConstraintsBO dsr = new DataSetRelationsConstraintsBO();

//测试一：关系

//Console.WriteLine("-----------------------------显示关系及数据");

//dsr.SetRelations();

//dsr.ShowConstraints();

//dsr.ShowRelationsTableData();

//dsr.ShowDataSet();

//Console.WriteLine("-----------------------------删除父表记录");

//dsr.DeleteBuildingRow();

//dsr.ShowRelationsTableData();

//dsr.ShowDataSet();

//Console.WriteLine("-----------------------------删除子表记录");

//dsr.DeleteRoomRow();

//dsr.ShowRelationsTableData();

//dsr.ShowDataSet();

//Console.WriteLine("-----------------------------更新父表主键");

//dsr.UpdateBuildingID(10);

//dsr.ShowRelationsTableData();

//dsr.ShowDataSet();

//测试二：主键约束

//dsr.SetPrimaryKeyConstraints();

//dsr.ShowConstraints();

//测试三：外键约束

//Console.WriteLine("-----------------------------显示约束及数据");

//dsr.SetForeignKeyConstraints();

//dsr.ShowConstraints();

//dsr.ShowDataSet();

//Console.WriteLine("-----------------------------删除父表记录，引发级联删除");

//dsr.DeleteBuildingRow();

//dsr.ShowDataSet();

//Console.WriteLine("-----------------------------删除子表记录");

//dsr.DeleteRoomRow();

//dsr.ShowDataSet();

//Console.WriteLine("-----------------------------更新父表主键，引发级联更新");

//dsr.UpdateBuildingID(10);

//dsr.ShowDataSet();

dsr.SetRelations();

dsr.Export();

}

//----------------------------------------------------------------------------------------------------------------------------

public void Export()

{

ds.WriteXml("data.xml");

ds.WriteXmlSchema("schema.xml");

}

//----------------------------------------------------------------------------------------------------------------------------

/// <summary>

/// 设置表之间的关系

/// </summary>

public void SetRelations()

{

//建立DataSet中表的关系

//说明一：主表的主键必须具有唯一性

//说明二：子表的所有记录的外建都必须为主表的主键，不能在主表中不存在；

//说明三：自动将Building中的BuildingID设置约束

//说明四：自动设置级联删除、级联更新约束

ds.Relations.Add("Rooms", ds.Tables["Building"].Columns["BuildingID"], ds.Tables["Room"].Columns["BuildingID"]);

}

/// <summary>

/// 显示关系表数据

/// </summary>

public void ShowRelationsTableData()

{

//遍历父表中的所有记录,并且显示出父表中每个记录对应子表中的所有记录;

Console.WriteLine("父表Building记录，并循环显示每个父表对应子表中的关系记录：");

foreach (DataRow theBuilding in ds.Tables["Building"].Rows)

{

//获取当前行所对应子表的所有记录行

DataRow[] children = theBuilding.GetChildRows("Rooms");

int roomCount = children.Length;

Console.WriteLine("Building{0} contains {1} room{2}",

theBuilding["Name"],

roomCount,

roomCount > 1 ? "s" : "");

foreach (DataRow theRoom in children)

{

Console.WriteLine(" Room:{0}", theRoom["Name"]);

}

}

//遍历子表中的所有记录,并且显示出子表中对应的父表中的记录信息

Console.WriteLine("子表Room记录：");

foreach (DataRow theRoom in ds.Tables["Room"].Rows)

{

DataRow parents = theRoom.GetParentRow("Rooms");

Console.WriteLine("Room {0} is contained in building {1}", theRoom["Name"], parents["Name"]);

}

}

//----------------------------------------------------------------------------------------------------------------------------

/// <summary>

/// 设置约束（主键码唯一约束）

/// </summary>

public void SetPrimaryKeyConstraints()

{

DataColumn[] buildingPK = new DataColumn[1];

buildingPK[0] = ds.Tables["Building"].Columns["BuildingID"];

ds.Tables["Building"].Constraints.Add(new UniqueConstraint("PK_Building", buildingPK));

ds.Tables["Building"].PrimaryKey = buildingPK;

DataColumn[] roomPK = new DataColumn[2];

roomPK[0] = ds.Tables["Room"].Columns["RoomID"];

roomPK[1] = ds.Tables["Room"].Columns["Name"];

ds.Tables["Room"].Constraints.Add(new UniqueConstraint("PK_Room", roomPK));

ds.Tables["Room"].PrimaryKey = roomPK;

}

/// <summary>

/// 设置约束（外键约束）

/// </summary>

public void SetForeignKeyConstraints()

{

//设置表Building的主键约束,Key为BuildingID

DataColumn[] buildingPK = new DataColumn[1];

buildingPK[0] = ds.Tables["Building"].Columns["BuildingID"];

ds.Tables["Building"].Constraints.Add(new UniqueConstraint("PK_Building", buildingPK));

ds.Tables["Building"].PrimaryKey = buildingPK;

//设置表Room的主键约束，Key为RoomID

DataColumn[] roomPK = new DataColumn[1];

roomPK[0] = ds.Tables["Room"].Columns["RoomID"];

ds.Tables["Room"].Constraints.Add(new UniqueConstraint("PK_Room", roomPK));

ds.Tables["Room"].PrimaryKey = roomPK;

//设置外键

//说明：设置外键后可以级联操作数据，但无法通过关系去访问数据（如：子表查找父表记录，父表查找子表记录）

DataColumn parent = ds.Tables["Building"].Columns["BuildingID"];

DataColumn child = ds.Tables["Room"].Columns["BuildingID"];

ForeignKeyConstraint fk = new ForeignKeyConstraint("FK_Product_CategoryID", parent, child);

fk.DeleteRule = Rule.Cascade; //设置级联删除

fk.UpdateRule = Rule.Cascade; //设置级联更新

ds.Tables["Room"].Constraints.Add(fk);

/*更新和删除约束

* Rule.Cascade：如果更新了父键，就应把亲的键值复制到所有子记录上。如果删除了父记录，也将删除子记录，这是默认选项。

* Rule.None：不执行任何操作，这个选项会留下数据表中的孤立行。

* Rule.SetDefault：如果定义了一个子记录，那么每个受影响的子记录都把外键码列设置为其默认值。

* Rule.SetNull：父记录删除或父记录更新主键时，所有的子行都把外键列设置为DBNull;

*/

}

/// <summary>

/// 显示约束

/// </summary>

public void ShowConstraints()

{

Console.WriteLine("表Building的约束：");

foreach (Constraint item in ds.Tables["Building"].Constraints)

{

Console.WriteLine(" Building ConstraintName：{0};", item.ConstraintName);

}

Console.WriteLine("表Room的约束：");

foreach (Constraint item in ds.Tables["Room"].Constraints)

{

Console.WriteLine(" Room ConstraintName：{0};", item.ConstraintName);

}

}

//----------------------------------------------------------------------------------------------------------------------------

/// <summary>

/// 删除Building行

/// </summary>

public void DeleteBuildingRow()

{

ds.Tables["Building"].Rows[0].Delete();

}

/// <summary>

/// 删除Room行

/// </summary>

public void DeleteRoomRow()

{

ds.Tables["Room"].Rows[0].Delete();

}

/// <summary>

/// 更新BuildingID

/// </summary>

/// <param name="buildingID">buildingID</param>

public void UpdateBuildingID(int buildingID)

{

ds.Tables["Building"].Rows[0][0] = buildingID;

}

//----------------------------------------------------------------------------------------------------------------------------

/// <summary>

/// 显示DataSet数据

/// </summary>

public void ShowDataSet()

{

Console.WriteLine("表Building的数据：");

foreach (DataRow item in ds.Tables["Building"].Rows)

{

Console.WriteLine("BuildingID={0}; Name={1}; ", item[0], item[1]);

}

Console.WriteLine("表Room的数据：");

foreach (DataRow item in ds.Tables["Room"].Rows)

{

Console.WriteLine("RoomID={0}; Name={1}; BuildingID={2}; ", item[0], item[1], item[2]);

}

}

//----------------------------------------------------------------------------------------------------------------------------

/// <summary>

/// 生成Building表

/// </summary>

/// <returns>DataTable</returns>

private DataTable CreateBuildingTable()

{

DataTable dt = new DataTable("Building");

dt.Columns.Add("BuildingID", typeof(int));

dt.Columns.Add("Name", typeof(string));

BuildingTableAddRow(1, "Building1", dt);

BuildingTableAddRow(2, "Building2", dt);

BuildingTableAddRow(3, "Building3", dt);

BuildingTableAddRow(4, "Building4", dt);

BuildingTableAddRow(5, "Building5", dt);

BuildingTableAddRow(6, "Building6", dt);

return (dt);

}

private void BuildingTableAddRow(int buildingID, string name, DataTable dt)

{

DataRow dr;

dr = dt.NewRow();

dr["BuildingID"] = buildingID;

dr["Name"] = name;

dt.Rows.Add(dr);

}

/// <summary>

/// 生成Room表

/// </summary>

/// <returns>DataTable</returns>

private DataTable CreateRoomTable()

{

DataTable dt = new DataTable("Room");

dt.Columns.Add("RoomID", typeof(int));

dt.Columns.Add("Name", typeof(string));

dt.Columns.Add("BuildingID", typeof(int));

RoomTableAddRow(1, "Room1", 1, dt);

RoomTableAddRow(2, "Room2", 1, dt);

RoomTableAddRow(3, "Room3", 1, dt);

RoomTableAddRow(4, "Room4", 1, dt);

RoomTableAddRow(5, "Room5", 2, dt);

RoomTableAddRow(6, "Room6", 2, dt);

RoomTableAddRow(7, "Room7", 2, dt);

RoomTableAddRow(8, "Room8", 3, dt);

RoomTableAddRow(9, "Room9", 3, dt);

return (dt);

}

private void RoomTableAddRow(int roomID, string name, int buildingID, DataTable dt)

{

DataRow dr;

dr = dt.NewRow();

dr["RoomID"] = roomID;

dr["BuildingID"] = buildingID;

dr["Name"] = name;

dt.Rows.Add(dr);

}

//----------------------------------------------------------------------------------------------------------------------------

}

}