using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace TestConsole
{/// <summary>/// 测试类/// </summary>
    [Serializable]public class TestDemo{/// <summary>/// 数据库连接字符串/// </summary>private readonly string connectionString = "server=.;database=TestDB;uid=sa;pwd=123456";/// <summary>/// 从数据库中查询所有记录/// </summary>/// <returns></returns>private DataTable GetTableFromDatabase(){using (SqlConnection conn = new SqlConnection(connectionString)){try{conn.Open();SqlDataAdapter sda = new SqlDataAdapter("select Id,Name,ValueA,ValueB from TestTable", conn);DataSet ds = new DataSet();sda.Fill(ds);DataTable dbTable = null;if (ds != null){dbTable = ds.Tables[0];}return dbTable;}catch (Exception e){throw e;}}}/// <summary>/// 修改/// </summary>/// <param name="value"></param>/// <param name="nameValue"></param>private void Update(int value, string nameValue){string updateSql = "update TestTable set ValueA=" + value + " where Name='" + nameValue + "'";using (SqlConnection conn = new SqlConnection(connectionString)){using (SqlCommand cmd = new SqlCommand(updateSql, conn)){try{conn.Open();int rows = cmd.ExecuteNonQuery();}catch (System.Data.SqlClient.SqlException e){conn.Close();throw e;}}}}/// <summary>/// 从内存获取DataTable/// </summary>/// <returns></returns>private DataTable GetTableFromMemory(){DataTable dt = new DataTable("TestTable");dt.Columns.Add("Id", typeof(System.Int32));dt.Columns.Add("Name", typeof(System.String));dt.Columns.Add("ValueA", typeof(System.Int32));dt.Columns.Add("ValueB", typeof(System.String));DataRow row;row = dt.NewRow();row["Id"] = 1;row["Name"] = "ItemA";row["ValueA"] = 20;dt.Rows.Add(row);row = dt.NewRow();row["Id"] = 67;row["Name"] = "ItemC";row["ValueA"] = 90;dt.Rows.Add(row);return dt;}/// <summary>/// 测试方法/// </summary>public void TestMethod(){String nameValue = "ItemC";//从内存获取DataTable，并找到值为ItemC的记录DataTable memoryTable = GetTableFromMemory();DataRow[] memoryArr = memoryTable.Select("Name='" + nameValue + "'");int valueA = 0;int.TryParse(memoryArr[0]["ValueA"].ToString(), out valueA);//将内存表中Name=ItemC的ValueA更新到数据表中
            Update(valueA, nameValue);//将数据库中的ValueB数据栏及其对应的值添加到内存表中DataTable dbTable = GetTableFromDatabase();if (dbTable != null && dbTable.Rows.Count > 0){//遍历数据表中的记录foreach (DataRow dr in dbTable.Rows){DataRow[] tempDR = memoryTable.Select("Name='" + dr["Name"] + "'");if (tempDR.Length > 0){tempDR[0]["ValueB"] = dr["ValueB"];}else{DataRow row = memoryTable.NewRow();row["Id"] = dr["Id"];row["Name"] = dr["Name"];row["ValueA"] = dr["ValueA"];row["ValueB"] = dr["ValueB"];memoryTable.Rows.Add(row);}}}}}
}