Question

谁会用SQL Server做一个简单的数据库系统?只需要实现简单的查询删除，添加修改等简单的功能就可以，很急啊

Answer 1

把下面这段代码放在一个Class里面，同时修改相应的连接串和表名称表字段，就可以实现增加删除修改查询四个功能：
------------------------------在web.config中
<connectionStrings>
<add name="Northwind" connectionString="Data Source=192.168.1.100;Initial Catalog=Northwind;User ID=sa;PassWord=sa" providerName="System.Data.SqlClient"/>
</connectionStrings>
---------------------------在C#中调用：
String ConnectionString = System.Configuration.ConfigurationManager.ConnectionStrings["Northwind"].ConnectionString
-----------------------------增删改查方法：
public int New(Entities.Ammeter obj)
{
String sql = "insert into Ammeter(AmmeterName,AmmeterNO,AmmeterTypeObjID,ApartmentObjID,BHNO,IsUsed,Multiplicator,ObjectID,ParentID,RealtyObjID,System) values(@AmmeterName,@AmmeterNO,@AmmeterTypeObjID,@ApartmentObjID,@BHNO,@IsUsed,@Multiplicator,@ObjectID,@ParentID,@RealtyObjID,@System)";

SqlConnection cn = new SqlConnection(this._ConnectionString);
SqlCommand cmd = new SqlCommand(sql, cn);
cmd.Parameters.AddWithValue("@AmmeterName", obj.AmmeterName);
cmd.Parameters.AddWithValue("@AmmeterNO", obj.AmmeterNO);
cmd.Parameters.AddWithValue("@AmmeterTypeObjID", obj.AmmeterTypeObjID);
cmd.Parameters.AddWithValue("@ApartmentObjID", obj.ApartmentObjID);
cmd.Parameters.AddWithValue("@BHNO", obj.BHNO);
cmd.Parameters.AddWithValue("@IsUsed", obj.IsUsed);
cmd.Parameters.AddWithValue("@Multiplicator", obj.Multiplicator);
cmd.Parameters.AddWithValue("@ObjectID",
String.Empty.Equals(obj.ObjectID) ? System.Guid.NewGuid().ToString() : obj.ObjectID);
cmd.Parameters.AddWithValue("@ParentID", obj.ParentID);
cmd.Parameters.AddWithValue("@RealtyObjID", obj.RealtyObjID);
cmd.Parameters.AddWithValue("@System", obj.System);
try
{
if (cn.State != ConnectionState.Open)
cn.Open();
return cmd.ExecuteNonQuery();
}
catch
{
return -1;
}
finally
{
if (cn.State != ConnectionState.Closed)
cn.Close();
}
}
public int Update(Entities.Ammeter obj)
{
String sql = "Update Ammeter Set AmmeterName=@AmmeterName,AmmeterNO=@AmmeterNO,AmmeterTypeObjID=@AmmeterTypeObjID,ApartmentObjID=@ApartmentObjID,BHNO=@BHNO,IsUsed=@IsUsed,Multiplicator=@Multiplicator,ParentID=@ParentID,RealtyObjID=@RealtyObjID,System=@System Where ObjectID=@ObjectID";

SqlConnection cn = new SqlConnection(this._ConnectionString);
SqlCommand cmd = new SqlCommand(sql, cn);
cmd.Parameters.AddWithValue("@AmmeterName", obj.AmmeterName);
cmd.Parameters.AddWithValue("@AmmeterNO", obj.AmmeterNO);
cmd.Parameters.AddWithValue("@AmmeterTypeObjID", obj.AmmeterTypeObjID);
cmd.Parameters.AddWithValue("@ApartmentObjID", obj.ApartmentObjID);
cmd.Parameters.AddWithValue("@BHNO", obj.BHNO);
cmd.Parameters.AddWithValue("@IsUsed", obj.IsUsed);
cmd.Parameters.AddWithValue("@Multiplicator", obj.Multiplicator);
cmd.Parameters.AddWithValue("@ObjectID", obj.ObjectID);
cmd.Parameters.AddWithValue("@ParentID", obj.ParentID);
cmd.Parameters.AddWithValue("@RealtyObjID", obj.RealtyObjID);
cmd.Parameters.AddWithValue("@System", obj.System);
try
{
if (cn.State != ConnectionState.Open)
cn.Open();
return cmd.ExecuteNonQuery();
}
catch
{
return -1;
}
finally
{
if (cn.State != ConnectionState.Closed)
cn.Close();
}
}
public int Del(Entities.Ammeter obj)
{
String sql = "delete from Ammeter Where ObjectID=@ObjectID";

SqlConnection cn = new SqlConnection(this._ConnectionString);
SqlCommand cmd = new SqlCommand(sql, cn);
cmd.Parameters.AddWithValue("@ObjectID", obj.ObjectID);
try
{
if (cn.State != ConnectionState.Open)
cn.Open();
return cmd.ExecuteNonQuery();
}
catch
{
return -1;
}
finally
{
if (cn.State != ConnectionState.Closed)
cn.Close();
}
}
public int Del(String where)
{
String sql = String.Format("delete from Ammeter Where {0}", where.ToLower().Replace("update", "").Replace("delete", ""));

SqlConnection cn = new SqlConnection(this._ConnectionString);
SqlCommand cmd = new SqlCommand(sql, cn);
try
{
if (cn.State != ConnectionState.Open)
cn.Open();
return cmd.ExecuteNonQuery();
}
catch
{
return -1;
}
finally
{
if (cn.State != ConnectionState.Closed)
cn.Close();
}
}
public DataTable Query(String pkField, Object pkid)
{
String sql = String.Format("select * from Ammeter Where {0}='{1}'", pkField.ToLower().Replace("update", "").Replace("delete", "").Replace("insert", "").Replace(";", "").Replace("--", "").Replace("exec", ""), pkid.ToString().ToLower().Replace("update", "").Replace("delete", "").Replace("insert", "").Replace(";", "").Replace("--", "").Replace("exec", ""));
try
{

SqlDataAdapter da = new SqlDataAdapter(sql, new SqlConnection(this._ConnectionString));
DataTable dt = new DataTable();
da.Fill(dt);
return dt;
}
catch
{
return null;
}
}
public DataTable Query(String where)
{
String sql = String.Format("select * from Ammeter Where {0}", where.ToLower().Replace("update", "").Replace("delete", "").Replace("insert", "").Replace(";", "").Replace("--", "").Replace("exec", ""));
try
{

SqlDataAdapter da = new SqlDataAdapter(sql, new SqlConnection(this._ConnectionString));
DataTable dt = new DataTable();
da.Fill(dt);
return dt;
}
catch
{
return null;
}
}

追问

怎么修改？还有在什么中调用啊，在web中实现是什么？

追答

1.数据库建表，
create table mytable(
pkid nvarchar(40) not null,
a nvarchar(40) null,
b nvarchar(40) null,
c nvarchar(40) null
)
2.新建对应此表的实体类
[Serializable]
public class mytable
{
private String _pkid = "";
public String pkid
{
get { return _a; }
set { _a = value; }
}
private String _a = "";
public String a
{
get { return _a; }
set { _a = value; }
}
private String _b = "";
public String b
{
get { return _b; }
set { _b = value; }
}
private String _c = "";
public String c
{
get { return _c; }
set { _c = value; }
}
}
3.新建操作类：
public class mytableDAO
{
private String _ConnectionString;
public mytableDAO(String ConnectionString)
{
this._ConnectionString = ConnectionString;
}
public int New(Entities.MsgRecord obj)
{
String sql = "insert into mytable(pkid,a,b,c) values(@pkid,@a,@b,@c)";
SqlConnection cn = new SqlConnection(this._ConnectionString);
SqlCommand cmd = new SqlCommand(sql, cn);
cmd.Parameters.AddWithValue("@a", obj.a);
cmd.Parameters.AddWithValue("@b", obj.b);
cmd.Parameters.AddWithValue("@c", obj.c);
cmd.Parameters.AddWithValue("@pkid",
String.Empty.Equals(obj.pkid) ? System.Guid.NewGuid().ToString() : obj.pkid);
try
{
if (cn.State != ConnectionState.Open)
cn.Open();
return cmd.ExecuteNonQuery();
---------内容未完，只允许写999个字，没办法，还有一大半放不上去。

Answer 2

不懂你的问题。sql的语句就可以实现你说的功能了。

Answer 3

是写SQL语句吗