数据集完全独立于数据源,可以与数据源链接或者完全断开,其基本作用是为存储在内存缓存中的的数据提供关系视图
如果只是想读取和显示数据,则值需要使用数据读取器,尤其是处理大量数据的时候
如果需要处理数据,然后更新数据库,就需要使用数据集
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数据来自数据源,数据适配器就像水管,数据集就像水桶,
数据适配器将数据总数据源导入到数据集中
如果把DataSet比作数据库,那么DataTable就是数据表,DataColumn就是列,DataRow就是行
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一、利用 DataAdapter 填充数据到 DataSet
static void Main(string[] args)
{
string connstr = @"Data Source=WIN-VD88F15CMMD;Initial Catalog=Key;User ID=sa;pwd=130988825";
string sql = "select kXh,kXm from [Class]";
using (SqlConnection conn = new SqlConnection(connstr))
{
using (SqlDataAdapter da = new SqlDataAdapter(sql, conn))
{
DataSet ds = new DataSet();
da.Fill(ds,"Class");
DataTable dt = ds.Tables["Class"];
foreach (DataRow row in dt.Rows) //遍历表
{
foreach (DataColumn col in dt.Columns)
Console.WriteLine(row[col]);
Console.WriteLine("".PadLeft(20,'='));
}
Console.ReadKey();
}
}
}
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二、有两个 DataTable 的 DataSet
static void Main(string[] args)
{
string connstr = @"Data Source=WIN-VD88F15CMMD;Initial Catalog=Key;User ID=sa;pwd=130988825";
string sqla = "select * from [Class]";
string sqlb = "select * from [Student]";
string sql = sqla + sqlb; //注意查询出两个数据表的sql是如何写的
using (SqlConnection conn = new SqlConnection(connstr))
{
using (SqlDataAdapter da = new SqlDataAdapter())
{
da.SelectCommand = new SqlCommand(sql,conn);
DataSet ds = new DataSet();
da.Fill(ds,"Class"); // 当第一的表被命名为Table时,第二个表默认为Table1
DataTableCollection dtc = ds.Tables;
string f1 = "kGender='男'";
string srt = "kXm asc";
foreach (DataRow row in dtc["Class"].Select(f1, srt))
{
Console.WriteLine("{0} {1}",row["kXm"].ToString().PadRight(25),row["kXh"]);
}
Console.ReadKey();
foreach (DataRow row in dtc[1].Rows) // 虽然第二个表默认为Table1,但是我们一般用序号索引来引出第二个表
{
Console.WriteLine("{0} {1}",row[1].ToString().PadRight(25),row[2]);
}
}
Console.ReadKey();
}
}
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三、利用 DataView 对 DataTable 中的数据进行 筛选排序
static void Main(string[] args)
{
string connstr = @"Data Source=WIN-VD88F15CMMD;Initial Catalog=Key;User ID=sa;pwd=130988825";
string sql = "select * from [Class]";
using (SqlConnection conn = new SqlConnection(connstr))
{
using (SqlDataAdapter da = new SqlDataAdapter())
{
da.SelectCommand = new SqlCommand(sql, conn);
DataSet ds = new DataSet();
da.Fill(ds, "Class");
DataTable dt=ds.Tables["Class"];
DataView dv = new DataView(
dt, //关联一个DataTable
"kGender='男'", //筛选器
"kXm", // 排序列
DataViewRowState.CurrentRows
);
foreach (DataRowView drv in dv)
{
for (int i = 0; i < dv.Table.Columns.Count; i++)
{
Console.WriteLine(drv[i]+" ");
Console.WriteLine();
}
}
Console.ReadKey();
}
}
}
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四、实现DataTable中数据的 增、删、改 并保存到数据源
1、数据集-数据的修改
static void Main(string[] args)
{
string connstr = @"Data Source=win-45022h0f9nsmysqlserver;Initial Catalog=CallCenter;Persist Security Info=True;User ID=sa;pwd=130988825";
string qry = @"select * from Student where sId=22";
string upd = @"update Student set sName=@sName where sId=@sId";
using (SqlConnection conn = new SqlConnection(connstr))
{
using (SqlDataAdapter sda = new SqlDataAdapter(qry, conn))
{
DataSet ds = new DataSet();
sda.Fill(ds,"Student");
DataTable dt =ds.Tables["Student"];
dt.Rows[0]["sName"] = "左杰"; //修改现有数据
SqlCommand cmd = new SqlCommand(upd,conn);
cmd.Parameters.Add("@sName",SqlDbType.NChar,10, "sName");
cmd.Parameters.Add("@sId", SqlDbType.Int,4,"sId");
sda.UpdateCommand = cmd;
sda.Update(ds,"Student");
}
}
}
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2、数据集-数据的增加
static void Main(string[] args)
{
string connstr = @"Data Source=win-45022h0f9nsmysqlserver;Initial Catalog=CallCenter;Persist Security Info=True;User ID=sa;pwd=130988825";
string qry = @"select * from Student where sId=23"; //选出的数据为空
string ins = @"insert into Student(sName,sGender,sAge,sClass,sId) values(@sName,@sGender,@sAge,@sClass,@sId)";
using (SqlConnection conn = new SqlConnection(connstr))
{
using (SqlDataAdapter sda = new SqlDataAdapter(qry, conn))
{
DataSet ds = new DataSet(); //选择出一个空的数据集
sda.Fill(ds,"Student");
DataTable dt=ds.Tables["Student"];
DataRow newrow = dt.NewRow();
newrow["sName"] = "胡章诚key";
newrow["sGender"]='男';
newrow["sAge"]=21;
newrow["sClass"] = 1;
newrow["sId"] = 23;
dt.Rows.Add(newrow);
SqlCommand cmd= new SqlCommand(ins,conn);
cmd.Parameters.Add("@sName", SqlDbType.NChar, 10, "sName");
cmd.Parameters.Add("@sGender", SqlDbType.Char, 2, "sGender");
cmd.Parameters.Add("@sAge", SqlDbType.Int, 4, "sAge");
cmd.Parameters.Add("@sClass", SqlDbType.Int, 4, "sClass");
cmd.Parameters.Add("@sId", SqlDbType.Int, 4, "sId");
sda.InsertCommand = cmd;
sda.Update(ds,"Student");
}
}
}
。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。
3、数据集-数据的删除
static void Main(string[] args)
{
string connstr = @"Data Source=win-45022h0f9nsmysqlserver;Initial Catalog=CallCenter;Persist Security Info=True;User ID=sa;pwd=130988825";
string qry = @"select * from Student where sClass=2";
string del = @"delete from Student where sClass=@sClass";
using (SqlConnection conn = new SqlConnection(connstr))
{
using (SqlDataAdapter sda = new SqlDataAdapter(qry, conn))
{
DataSet ds = new DataSet();
sda.Fill(ds,"Student");
DataTable dt=ds.Tables["Student"];
SqlCommand cmd = new SqlCommand(del,conn);
cmd.Parameters.Add("@sClass", SqlDbType.Int, 4, "sClass");
foreach (DataRow row in dt.Rows)
{
row.Delete();
}
sda.DeleteCommand = cmd;
sda.Update(ds,"Student");
}
}
}