0.

建一个通用的处理数据的类

using System;
using System.Data;
using System.Data.SqlClient;
using System.Text;
namespace Document
{
/** <summary>
/// Summary description for DataHelper.
/// </summary>
public class DataHelper
{
public DataHelper()
{
//
// TODO: Add constructor logic here
//
}
public static string ConnectionString=System.Configuration.ConfigurationSettings.AppSettings["ConnectionString"];
GetDataSet#region GetDataSet
public static DataSet GetDataSet(string sql)
{
SqlDataAdapter    sda =new SqlDataAdapter(sql,ConnectionString);
DataSet ds=new DataSet();
sda.Fill(ds);
return ds;
}
#endregion
ExecCommand#region ExecCommand
public static int ExecCommand(SqlCommand sqlcom)
{
SqlConnection conn=new SqlConnection(ConnectionString);
sqlcom.Connection =conn;
conn.Open();
try
{
int rtn=sqlcom.ExecuteNonQuery();
return rtn;
}
catch(Exception ex)
{
throw ex;
}
finally
{
conn.Close();
}
return 0;
}
public static int ExecCommand(string sql)
{
if (sql.EndsWith(",")) sql=sql.Substring(0,sql.Length-1);
SqlCommand sqlcom=new SqlCommand(sql);
return ExecCommand(sqlcom);
}
#endregion
ExecuteScalar#region ExecuteScalar
public static object ExecuteScalar(string sql)
{
SqlConnection conn=new SqlConnection(ConnectionString);
SqlCommand sqlcom=new SqlCommand(sql,conn);
conn.Open();
try
{
object rtn=sqlcom.ExecuteScalar ();
return rtn;
}
catch(Exception ex)
{
throw ex;
}
finally
{
conn.Close();
}
return null;
}
#endregion
ExecSPCommand#region ExecSPCommand
public static void ExecSPCommand(string sql,System.Data.IDataParameter[] paramers)
{
SqlConnection conn=new SqlConnection(ConnectionString);
SqlCommand sqlcom=new SqlCommand(sql,conn);
sqlcom.CommandType= CommandType.StoredProcedure ;
foreach(System.Data.IDataParameter paramer in paramers)
{
sqlcom.Parameters.Add(paramer);
}
conn.Open();
try
{
sqlcom.ExecuteNonQuery();
}
catch(Exception ex)
{
string s=ex.Message ;
}
finally
{
conn.Close();
}
}
#endregion
ExecSPDataSet#region ExecSPDataSet
public static DataSet ExecSPDataSet(string sql,System.Data.IDataParameter[] paramers)
{
SqlConnection conn=new SqlConnection(ConnectionString);
SqlCommand sqlcom=new SqlCommand(sql,conn);
sqlcom.CommandType= CommandType.StoredProcedure ;
foreach(System.Data.IDataParameter paramer in paramers)
{
sqlcom.Parameters.Add(paramer);
}
conn.Open();
SqlDataAdapter da=new SqlDataAdapter();
da.SelectCommand=sqlcom;
DataSet ds=new DataSet();
da.Fill(ds);
conn.Close();
return ds;
}
#endregion
DbType#region DbType
private static System.Data.DbType GetDbType(Type type)
{
DbType result = DbType.String;
if( type.Equals(typeof(int)) ||  type.IsEnum)
result = DbType.Int32;
else if( type.Equals(typeof(long)))
result = DbType.Int32;
else if( type.Equals(typeof(double)) || type.Equals( typeof(Double)))
result = DbType.Decimal;
else if( type.Equals(typeof(DateTime)))
result = DbType.DateTime;
else if( type.Equals(typeof(bool)))
result = DbType.Boolean;
else if( type.Equals(typeof(string) ) )
result = DbType.String;
else if( type.Equals(typeof(decimal)))
result = DbType.Decimal;
else if( type.Equals(typeof(byte[])))
result = DbType.Binary;
else if( type.Equals(typeof(Guid)))
result = DbType.Guid;
return result;
}
#endregion
UpdateTable#region UpdateTable
public static void UpdateTable(DataTable dt,string TableName,string KeyName)
{
foreach(DataRow dr in dt.Rows)
{
updateRow(dr,TableName,KeyName);
}
}
#endregion
InsertTable#region InsertTable
//用于主键是数据库表名+ID类型的
public static void InsertTable(DataTable dt)
{
string TableName="["+dt.TableName+"]";
string KeyName=dt.TableName+"ID";
foreach(DataRow dr in dt.Rows)
{
insertRow(dr,TableName,KeyName);
}
}
//用于主键是任意类型的
public static void InsertTable(DataTable dt,string KeyName)
{
string TableName="["+dt.TableName+"]";
foreach(DataRow dr in dt.Rows)
{
insertRow(dr,TableName,KeyName);
}
}
#endregion
DeleteTable#region DeleteTable
public static void DeleteTable(DataTable dt,string KeyName)
{
string TableName="["+dt.TableName+"]";
foreach(DataRow dr in dt.Rows)
{
deleteRow(dr,TableName,KeyName);
}
}
#endregion
updateRow#region updateRow
private static void  updateRow(DataRow dr,string TableName,string KeyName)
{
if (dr[KeyName]==DBNull.Value )
{
throw new Exception(KeyName +"的值不能为空");
}
if (dr.RowState ==DataRowState.Deleted)
{
deleteRow(dr,TableName,KeyName);
}
else if (dr.RowState ==DataRowState.Modified )
{
midifyRow(dr,TableName,KeyName);
}
else if (dr.RowState ==DataRowState.Added  )
{
insertRow(dr,TableName,KeyName);
}
else if (dr.RowState ==DataRowState.Unchanged )
{
midifyRow(dr,TableName,KeyName);
}
}
#endregion
deleteRow#region deleteRow
private static void  deleteRow(DataRow dr,string TableName,string KeyName)
{
string sql="Delete {0} where {1} =@{1}";
DataTable dtb=dr.Table ;
sql=string.Format(sql,TableName,KeyName);
SqlCommand sqlcom=new SqlCommand(sql);
System.Data.IDataParameter iparam=new  SqlParameter();
iparam.ParameterName    = "@"+ KeyName;
iparam.DbType            = GetDbType(dtb.Columns[KeyName].DataType);
iparam.Value            = dr[KeyName];
sqlcom.Parameters .Add(iparam);
ExecCommand(sqlcom);
}
#endregion
midifyRow#region midifyRow
private static void  midifyRow(DataRow dr,string TableName,string KeyName)
{
string UpdateSql            = "Update {0} set {1} {2}";
string setSql="{0}= @{0}";
string wherSql=" Where {0}=@{0}";
StringBuilder setSb    = new StringBuilder();
SqlCommand sqlcom=new SqlCommand();
DataTable dtb=dr.Table;
for (int k=0; k<dr.Table.Columns.Count; ++k)
{
System.Data.IDataParameter iparam=new  SqlParameter();
iparam.ParameterName    = "@"+ dtb.Columns[k].ColumnName;
iparam.DbType            = GetDbType(dtb.Columns[k].DataType);
iparam.Value            = dr[k];
sqlcom.Parameters .Add(iparam);
if (dtb.Columns[k].ColumnName==KeyName)
{
wherSql=string.Format(wherSql,KeyName);
}
else
{
setSb.Append(string.Format(setSql,dtb.Columns[k].ColumnName));
setSb.Append(",");
}
}
string setStr=setSb.ToString();
setStr=setStr.Substring(0,setStr.Length -1); //trim ,
string sql = string.Format(UpdateSql, TableName, setStr,wherSql);
sqlcom.CommandText =sql;
try
{
ExecCommand(sqlcom);
}
catch(Exception ex)
{
throw ex;
}
}
#endregion
insertRow#region insertRow
private static void  insertRow(DataRow dr,string TableName,string KeyName)
{
string InsertSql = "Insert into {0}({1}) values({2})";
SqlCommand sqlcom=new SqlCommand();
DataTable dtb=dr.Table ;
StringBuilder insertValues    = new StringBuilder();
StringBuilder cloumn_list    = new StringBuilder();
for (int k=0; k<dr.Table.Columns.Count; ++k)
{
//just for genentae，
if (dtb.Columns[k].ColumnName==KeyName) continue;
System.Data.IDataParameter iparam=new  SqlParameter();
iparam.ParameterName    = "@"+ dtb.Columns[k].ColumnName;
iparam.DbType            = GetDbType(dtb.Columns[k].DataType);
iparam.Value            = dr[k];
sqlcom.Parameters .Add(iparam);
cloumn_list.Append(dtb.Columns[k].ColumnName);
insertValues.Append("@"+dtb.Columns[k].ColumnName);
cloumn_list.Append(",");
insertValues.Append(",");
}
string cols=cloumn_list.ToString();
cols=cols.Substring(0,cols.Length -1);
string values=insertValues.ToString();
values=values.Substring(0,values.Length -1);
string sql = string.Format(InsertSql, TableName,cols ,values);
sqlcom.CommandText =sql;
try
{
ExecCommand(sqlcom);
}
catch(Exception ex)
{
throw ex;
}
}
#endregion
}
}

2..调用范例

        Insert#region Insert
private void InsertUserInfo()
{
DataTable dt=ds.Tables[0];
dt.TableName="UserInfo";
string keyname="UserInfoID";
DataRow dr=dt.NewRow();
dr["LoginName"]=this.txtUserName.Value;
dr["Pass"]=this.txtPassword.Value;
dr["NickName"]=this.txtNickName.Value;
dr["UserType"]=1;
dr["IsActive"]=false;
dr["RegisterDate"]=System.DateTime.Now;
dt.Rows.Add(dr);
dt.AcceptChanges();
DataHelper.InsertTable(dt,keyname);
}
#endregion
Update#region Update
private void UpdateUserInfo(string UserID)
{
DataSet ds=GetUserOther(UserID);
DataTable dt=ds.Tables[0];
dt.TableName="UserInfo";
string keyname="UserID";
DataRow dr=dt.Rows[0];
dr["LoginName"]=this.txtUserName.Value;
dr["Pass"]=this.txtPassword.Value;
dr["NickName"]=this.txtNickName.Value;
dr["UserType"]=1;
dr["IsActive"]=false;
dr["RegisterDate"]=System.DateTime.Now;
dt.Rows.Add(dr);
dt.AcceptChanges();
DataHelper.UpdateTable(dt,dt.TableName,keynanme);
}
#endregion
Delete

1.

// // // // //

1 using System;
  2  using System.Collections.Generic;
  3 using System.Data.SqlClient;
  4 using System.Configuration;
  5 using System.Data;
  6
  7 namespace Common
  8 {
  9     public abstractclass DbHelperSQL
10     {
11         //格式化字符串
12         public staticstring inSQL(string formatStr)
13         {
14            string Str= formatStr;
15            if (formatStr!=null&& formatStr!=string.Empty)
16             {
17                 Str= Str.Replace("'","''");
18             }
19            return Str;
20         }
21
22         //获取连接字符串
23         public staticstring ConnectionString
24         {
25            get
26             {
27                string _connectionstring= ConfigurationManager.ConnectionStrings["ApplicationServices"].ConnectionString;
28                string ConStringEncrypt= ConfigurationManager.AppSettings["ApplicationServices"];
29                if (ConStringEncrypt=="true")
30                 {
31                     _connectionstring= DESEncrypt.Encrypt(_connectionstring);
32                 }
33                return _connectionstring;
34             }
35         }
36
37         #region 执行带参数的SQL语句
38
39         // 执行查询语句，返回SqlDataReader ( 注意：调用该方法后，一定要对SqlDataReader进行Close )
40         public static  SqlDataReader ExecuteReader(string SQLString,params SqlParameter[] cmdParms)
41         {
42             SqlConnection connection=new SqlConnection(ConnectionString);
43             SqlCommand cmd=new SqlCommand();
44            try
45             {
46                 PrepareCommand(cmd,connection,null,SQLString,cmdParms);
47                 SqlDataReader myReader=cmd.ExecuteReader(CommandBehavior.CloseConnection);
48                 cmd.Parameters.Clear();
49                return myReader;
50             }
51            catch(System.Data.SqlClient.SqlException e)
52             {
53                throw e;
54             }
55         }
56
57         // 执行SQL语句，返回影响的记录数
58         public staticint ExecuteSql(string SQLString,params SqlParameter[] cmdParms)
59         {
60            using (SqlConnection connection=new SqlConnection(ConnectionString))
61             {
62                using (SqlCommand cmd=new SqlCommand())
63                 {
64                    try
65                     {
66                         PrepareCommand(cmd,connection,null,SQLString,cmdParms);
67                        int rows=cmd.ExecuteNonQuery();
68                         cmd.Parameters.Clear();
69                        return rows;
70                     }
71                    catch(System.Data.SqlClient.SqlException e)
72                     {
73                        throw e;
74                     }
75                 }
76             }
77         }
78        
79         // 执行查询语句，返回DataSet
80         private staticvoid PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans,string cmdText, SqlParameter[] cmdParms)
81         {
82            if (conn.State!= ConnectionState.Open)
83                 conn.Open();
84             cmd.Connection= conn;
85             cmd.CommandText= cmdText;
86            if (trans!= null)
87                 cmd.Transaction= trans;
88             cmd.CommandType= CommandType.Text;
89            if (cmdParms!=null)
90             {
91                foreach (SqlParameter parameterin cmdParms)
92                 {
93                    if ((parameter.Direction== ParameterDirection.InputOutput|| parameter.Direction== ParameterDirection.Input)&&
94                         (parameter.Value==null))
95                     {
96                         parameter.Value= DBNull.Value;
97                     }
98                     cmd.Parameters.Add(parameter);
99                 }
100             }
101         }
102
103        #endregion
104     }
105 }
106

///

///

3.

DBHelper.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

namespace PracticeMyBookShopDAL
{
    public static class DBHelper
    {

private static SqlConnection connection;
        public static SqlConnection Connection
        {
            get
            {
                //string connectionString = "Data Source=localhost;Initial Catalog=MyBookShop;User ID=sa;password=123456";

string connectionString = "Data Source=localhost;Initial Catalog=MyBookShop;User ID=sa;password=123456";
              
               
                if (connection == null)
                {
                    connection = new SqlConnection(connectionString);
                    connection.Open();
                }
                else if (connection.State == System.Data.ConnectionState.Closed)
                {
                    connection.Open();
                }
                else if (connection.State == System.Data.ConnectionState.Broken)
                {
                    connection.Close();
                    connection.Open();
                }
                return connection;
            }
        }

public static int ExecuteCommand(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            int result = cmd.ExecuteNonQuery();
            return result;
        }

public static int ExecuteCommand(string sql, SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            return cmd.ExecuteNonQuery();
        }

public static int ExecuteCommand(string sql, SqlParameter value)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.Add(value);
            int result = cmd.ExecuteNonQuery();
            return result;
        }

public static int ExecuteScalar(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            int result = (int)cmd.ExecuteScalar();
            return result;
        }

public static int ExecuteScalar(string sql, SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            int result = (int)cmd.ExecuteScalar();
            return result;
        }

public static int ExecuteScalar(string sql, SqlParameter value)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.Add(value);
            int result = (int)cmd.ExecuteScalar();
            return result;
        }

public static SqlDataReader ExecuteReader(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            SqlDataReader reader = cmd.ExecuteReader();
            return reader;
        }

public static SqlDataReader ExecuteReader(string sql, SqlParameter value)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.Add(value);
            SqlDataReader reader = cmd.ExecuteReader();
            return reader;
        }

public static SqlDataReader ExecuteReader(string sql, SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            SqlDataReader reader = cmd.ExecuteReader();
            return reader;
        }
        public static DataTable GetDataSet(string safeSql)
        {
            DataSet ds = new DataSet();
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(ds);
            return ds.Tables[0];
        }

public static DataTable GetDataSet(string sql, params SqlParameter[] values)
        {
            DataSet ds = new DataSet();
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(ds);
            return ds.Tables[0];
        }

public static SqlDataReader GetReader(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            SqlDataReader reader = cmd.ExecuteReader();
            return reader;
        }

public static SqlDataReader GetReader(string sql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            SqlDataReader reader = cmd.ExecuteReader();
            return reader;
        }

}
}

其中一个DAL：

using System;
using System.Collections.Generic;
using System.Text;
using PracticeMyBookShopModels;
using System.Data;
using System.Data.SqlClient;
namespace PracticeMyBookShopDAL
{
    public static class UserService
    {
        public static IList<User> GetAllUsers()
        {
            string sqlAll = "SELECT * FROM Users";
            return GetUsersBySql(sqlAll);
        }
        public static void DeleteUserById(int id)
        {
            string sql = "DELETE Users WHERE Id = @Id";

SqlParameter[] para = new SqlParameter[]
    {
     new SqlParameter("@Id", id)
    };

DBHelper.ExecuteCommand(sql, para);
          
          
        }
        public static IList<User> GetUserByRole(int userRoleId)
        {
            string sql = "SELECT * FROM Users WHERE UserRoleId = @UserRoleId";

return GetUsersBySql(sql, new SqlParameter("@UserRoleId", userRoleId));
          
        }
  private static IList<User> GetUsersBySql( string sql, params SqlParameter[] values )
        {
            List<User> list = new List<User>();

DataTable table = DBHelper.GetDataSet( sql, values );
    
    foreach (DataRow row in table.Rows)
    {
     User user = new User();
     
     user.Id = (int)row["Id"];
     user.LoginId = (string)row["LoginId"];
     user.LoginPwd = (string)row["LoginPwd"];
     user.Name = (string)row["Name"];
     user.Address = (string)row["Address"];
     user.Phone = (string)row["Phone"];
     user.Mail = (string)row["Mail"];
     user.UserState = UserStateService.GetUserStateById((int)row["UserStateId"]); //FK
     user.UserRole = UserRoleService.GetUserRoleById((int)row["UserRoleId"]); //FK
 
     list.Add(user);
    }
 
    return list;
   
    
      
  
 }

private static IList<User> GetUsersBySql(string safeSql)
        {
            List<User> list = new List<User>();

DataTable table = DBHelper.GetDataSet(safeSql);

foreach (DataRow row in table.Rows)
                {
                    User user = new User();

user.Id = (int)row["Id"];
                    user.LoginId = (string)row["LoginId"];
                    user.LoginPwd = (string)row["LoginPwd"];
                    user.Name = (string)row["Name"];
                    user.Address = (string)row["Address"];
                    user.Phone = (string)row["Phone"];
                    user.Mail = (string)row["Mail"];
                    user.UserState = UserStateService.GetUserStateById((int)row["UserStateId"]); //FK
                    user.UserRole = UserRoleService.GetUserRoleById((int)row["UserRoleId"]); //FK

list.Add(user);
                }

return list;
            }

/// 更改会员状态
         
            public static void ModifyUserStatus(int id, int status)
            {
                string sql = "Update users SET userstateid =" + status + " WHERE Id = @UserId";

DBHelper.ExecuteCommand(sql, new SqlParameter("@UserId", id));

}

}
}

///

///

4.

DBHelper.cs:

namespace BankDAL
{
    public static class DBHelper
    {
        private static SqlConnection connection;
        public static SqlConnection Connection
        {
            get
            {
                string connectionString = ConfigurationManager.ConnectionStrings["BankConnectionString"].ConnectionString;
                if (connection == null)
                {
                    connection = new SqlConnection(connectionString);
                    connection.Open();
                }
                else if (connection.State == System.Data.ConnectionState.Closed)
                {
                    connection.Open();
                }
                else if (connection.State == System.Data.ConnectionState.Broken)
                {
                    connection.Close();
                    connection.Open();
                }
                return connection;
            }
        }

public static int ExecuteCommand(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            int result = cmd.ExecuteNonQuery();
            return result;
        }

public static int ExecuteCommand(string sql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            return cmd.ExecuteNonQuery();
        }

public static int GetScalar(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            int result = Convert.ToInt32(cmd.ExecuteScalar());
            return result;
        }

public static int GetScalar(string sql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            int result = Convert.ToInt32(cmd.ExecuteScalar());
            return result;
        }

public static SqlDataReader GetReader(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            SqlDataReader reader = cmd.ExecuteReader();
            return reader;
        }

public static SqlDataReader GetReader(string sql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            SqlDataReader reader = cmd.ExecuteReader();
            return reader;
        }

public static DataTable GetDataSet(string safeSql)
        {
            DataSet ds = new DataSet();
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(ds);
            return ds.Tables[0];
        }

public static DataTable GetDataSet(string sql, params SqlParameter[] values)
        {
            DataSet ds = new DataSet();
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(ds);
            return ds.Tables[0];
        }
    }
}

DAL:

namespace Bank.DAL
{
    public static class UserService
    {
        /// <summary>
        /// 添加新用户
        /// </summary>
        /// <param name="user"></param>
        /// <returns></returns>
        public static Users AddUser(Users user)
        {
            string sql =
                "INSERT Users (Users_Account,Users_Pwd,Total_Money)" +
                "VALUES (@Users_Account, @Users_Pwd, @Total_Money)";
            sql += " ; SELECT @@IDENTITY";
            SqlParameter[] para = new SqlParameter[]
   {
    new SqlParameter("@Users_Account", user.Users_Account),
    new SqlParameter("@Users_Pwd", user.Users_Pwd),
    new SqlParameter("@Total_Money", user.Total_Money),

};
            int newId = DBHelper.GetScalar(sql, para);
            return GetUserById(newId);
        }

public static Users GetUserById(int id)
        {
            string sql = "SELECT * FROM Users WHERE Users_Id = @Id";
       
            using (SqlDataReader reader = DBHelper.GetReader(sql, new SqlParameter("@Id", id)))
            {
                if (reader.Read())
                {
                    Users user = new Users();
                    user.Users_Id = (int)reader["Users_Id"];
                    user.Users_Account = (string)reader["Users_Account"];
                    user.Users_Pwd = (string)reader["Users_Pwd"];
                    user.Total_Money= (double)reader["Total_Money"];
               
                    reader.Close();
                 
                    return user;
                }
                else
                {
                    reader.Close();
                    return null;
                }
            }
        }

public static Users GetUserByUsersAccount(string users_Account)
        {
            string sql = "SELECT * FROM Users WHERE Users_Account = @users_Account";

using (SqlDataReader reader = DBHelper.GetReader(sql, new SqlParameter("@Id", users_Account)))
            {
                if (reader.Read())
                {
                    Users user = new Users();
                    user.Users_Id = (int)reader["Users_Id"];
                    user.Users_Account = (string)reader["Users_Account"];
                    user.Users_Pwd = (string)reader["Users_Pwd"];
                    user.Total_Money = (double)reader["Total_Money"];

reader.Close();

return user;
                }
                else
                {
                    reader.Close();
                    return null;
                }
            }
        }
    
    }
}

BLL:

namespace BankBLL
{
    public static class UserManager
    {

public static bool Login(string users_Account, string users_Pwd, out Users validUser)
        {
            Users user = UserService.GetUserByUsersAccount(users_Account);
            if (user == null)
            {
                //用户名不存在
                validUser = null;
                return false;
            }

if (user.Users_Pwd == users_Pwd)
            {
                validUser = user;
                return true;
            }
            else
            {
                //密码错误
                validUser = null;
                return false;
            }
        }

public static string LoginValidate(string users_Account, string users_Pwd)
        {
            Users user = UserService.GetUserByUsersAccount(users_Account);
            if (user == null)
            {

return "failure";
            }

if (user.Users_Pwd == users_Pwd)
            {

return "success";
            }
            else
            {

return "failure";
            }
        }

public static string FindToAccount(string users_Account)
        {
            Users user = UserService.GetUserByUsersAccount(users_Account);
            if (user != null)
            {

return "success";
            }
            else
            {

return "failure";
            }
        }

public static string FindTotalMoney(double totalMoney)
        {
            throw new NotImplementedException();
        }
    }
}

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