重拾MVC——第一天：数据库连接与SqlDbHelper
2024-09-05 05:47:51
这个 SqlDbHelper 是我参考网上的和以前用过的 SqlDbHelper 自己写的一个非常简单的东西，主要是记录自己的学习情况
首先在Web.config中配置数据库连接字符串:
<connectionStrings>
<add name="TestConnectionStrings" connectionString="Data Source=服务器地址;Initial Catalog=数据库名称;User ID=sa;Password=密码" providerName="System.Data.SqlClient" />
</connectionStrings>
然后新建DbHelper文件夹，创建SqlDbHelper类：
public class DbHelper
{
private string connectionString = "";
protected SqlConnection conn = null; #region //构造函数
public DbHelper()
{
//this.connectionString = System.Web.Configuration.WebConfigurationManager.ConnectionStrings["DBConnectionString"].ToString();
this.connectionString = ConfigurationManager.ConnectionStrings["TestConnectionStrings"].ConnectionString;
this.conn = new SqlConnection(connectionString);
}
#endregion #region //打开连接
public void OpenDb()
{
if (conn.State != ConnectionState.Open)
{
try
{
conn.Open();
}
catch (SqlException ex)
{
throw ex;
}
}
}
#endregion #region //关闭连接
public void CloseDb()
{
if (!object.Equals(conn, null) && (conn.State != ConnectionState.Closed))
{
conn.Close();
}
}
#endregion #region //释放连接
public void Dispose()
{
if (conn != null)
{
conn.Dispose();
conn = null;
}
}
#endregion #region //执行单条SQL(插入、更新、删除)
/// <summary>
/// 执行单条SQL(插入、更新、删除)
/// </summary>
/// <param name="sql_"></param>
public void ExecuteNonQuery(string sql_)
{
try
{
OpenDb();
SqlCommand cm = new SqlCommand(sql_, conn);
cm.ExecuteNonQuery();
cm.Dispose();
cm = null;
CloseDb();
}
catch (Exception ex)
{
throw new Exception(ex.ToString() + " " + sql_);
}
}
#endregion #region //用于执行带参的SQL(插入、更新、删除)
/// <summary>
/// 用于执行带参的SQL(插入、更新、删除)
/// </summary>
/// <param name="sql">sql语句</param>
/// <param name="parameter">参数化查询</param>
/// <returns>有多少语句执行成功</returns>
public int ExecuteNonQuery(string sql, params SqlParameter[] parameter)
{
try
{
OpenDb();
SqlCommand cmd = conn.CreateCommand();
//SqlCommand cm = new SqlCommand(sql_, conn);
cmd.CommandText = sql;
cmd.Parameters.AddRange(parameter);
int rows = cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return rows;
}
catch (Exception ex)
{
throw new Exception(ex.ToString() + " " + sql);
}
}
#endregion #region //执行查询语句，返回SqlDataReader
/// <summary>
/// 执行查询语句，返回SqlDataReader
/// </summary>
/// <param name="sql"></param>
/// <param name="parameter"></param>
/// <returns></returns>
public SqlDataReader ExecuteReader(string sql, params SqlParameter[] parameter)
{
try
{
conn.Open();
SqlCommand cmd = conn.CreateCommand();
cmd.CommandText = sql;
cmd.Parameters.AddRange(parameter);
//return cmd.ExecuteReader(CommandBehavior.CloseConnection);
SqlDataReader myReader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
cmd.Parameters.Clear();
return myReader;
}
catch (Exception ex)
{
throw new Exception(ex.ToString() + " " + sql);
}
}
#endregion #region //执行查询语句，返回DataTable
/// <summary>
/// 执行查询语句，返回DataTable
/// </summary>
/// <param name="sqlString">查询语句</param>
/// <param name="cmdParms"></param>
/// <returns>DataSet</returns>
public DataTable GetDataTable(string sql, params SqlParameter[] parameter)
{
try
{
conn.Open();
SqlCommand cmd = conn.CreateCommand();
cmd.CommandText = sql;
cmd.Parameters.AddRange(parameter); using (var da = new SqlDataAdapter(cmd))
{
var dt = new DataTable();
var ds = new DataSet();
try
{
da.Fill(ds, "ds");
if (ds.Tables.Count <= 0)
return null;
dt = ds.Tables[0]; cmd.Parameters.Clear();
}
catch (SqlException ex)
{
throw new Exception(ex.Message);
}
return dt;
}
}
catch (Exception ex)
{
throw new Exception(ex.ToString() + " " + sql);
}
}
#endregion #region //执行查询语句，返回DataSet
/// <summary>
/// 执行查询语句，返回DataSet
/// </summary>
/// <param name="sqlString">查询语句</param>
/// <param name="cmdParms"></param>
/// <returns>DataSet</returns>
public DataSet GetDataSet(string sql, params SqlParameter[] parameter)
{
using (var connection = new SqlConnection(connectionString))
{
conn.Open();
SqlCommand cmd = conn.CreateCommand();
cmd.CommandText = sql;
cmd.Parameters.AddRange(parameter); using (var da = new SqlDataAdapter(cmd))
{
var ds = new DataSet();
try
{
da.Fill(ds, "ds");
cmd.Parameters.Clear();
}
catch (SqlException ex)
{
throw new Exception(ex.Message);
}
return ds;
}
}
}
#endregion }
在这其中，先获得Web.config中的连接数据库的字符串：
private string connectionString = "";
protected SqlConnection conn = null; #region //构造函数
public DbHelper()
{
//this.connectionString = System.Web.Configuration.WebConfigurationManager.ConnectionStrings["DBConnectionString"].ToString();
this.connectionString = ConfigurationManager.ConnectionStrings["TestConnectionStrings"].ConnectionString;
this.conn = new SqlConnection(connectionString);
}
#endregion
然后写连接打开/关闭/释放的方法
#region //打开连接
public void OpenDb()
{
if (conn.State != ConnectionState.Open)
{
try
{
conn.Open();
}
catch (SqlException ex)
{
throw ex;
}
}
}
#endregion #region //关闭连接
public void CloseDb()
{
if (!object.Equals(conn, null) && (conn.State != ConnectionState.Closed))
{
conn.Close();
}
}
#endregion #region //释放连接
public void Dispose()
{
if (conn != null)
{
conn.Dispose();
conn = null;
}
}
#endregion
下面写增删改的方法，我写了两种，带参的和不带参的
#region //执行单条SQL(插入、更新、删除)
/// <summary>
/// 执行单条SQL(插入、更新、删除)
/// </summary>
/// <param name="sql_"></param>
public void ExecuteNonQuery(string sql_)
{
try
{
OpenDb();
SqlCommand cm = new SqlCommand(sql_, conn);
cm.ExecuteNonQuery();
cm.Dispose();
cm = null;
CloseDb();
}
catch (Exception ex)
{
throw new Exception(ex.ToString() + " " + sql_);
}
}
#endregion #region //用于执行带参的SQL(插入、更新、删除)
/// <summary>
/// 用于执行带参的SQL(插入、更新、删除)
/// </summary>
/// <param name="sql">sql语句</param>
/// <param name="parameter">参数化查询</param>
/// <returns>有多少语句执行成功</returns>
public int ExecuteNonQuery(string sql, params SqlParameter[] parameter)
{
try
{
OpenDb();
SqlCommand cmd = conn.CreateCommand();
//SqlCommand cm = new SqlCommand(sql_, conn);
cmd.CommandText = sql;
cmd.Parameters.AddRange(parameter);
int rows = cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return rows;
}
catch (Exception ex)
{
throw new Exception(ex.ToString() + " " + sql);
}
}
#endregion
然后是查询，查询我写了三种，第一中返回的 SqlDataReader :
#region //执行查询语句，返回SqlDataReader
/// <summary>
/// 执行查询语句，返回SqlDataReader
/// </summary>
/// <param name="sql"></param>
/// <param name="parameter"></param>
/// <returns></returns>
public SqlDataReader ExecuteReader(string sql, params SqlParameter[] parameter)
{
try
{
conn.Open();
SqlCommand cmd = conn.CreateCommand();
cmd.CommandText = sql;
cmd.Parameters.AddRange(parameter);
//return cmd.ExecuteReader(CommandBehavior.CloseConnection);
SqlDataReader myReader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
cmd.Parameters.Clear();
return myReader;
}
catch (Exception ex)
{
throw new Exception(ex.ToString() + " " + sql);
}
}
#endregion
这里用完一定要对SqlDataReader进行Close
第二种返回的DateTable：
#region //执行查询语句，返回DataTable
/// <summary>
/// 执行查询语句，返回DataTable
/// </summary>
/// <param name="sqlString">查询语句</param>
/// <param name="cmdParms"></param>
/// <returns>DataSet</returns>
public DataTable GetDataTable(string sql, params SqlParameter[] parameter)
{
try
{
conn.Open();
SqlCommand cmd = conn.CreateCommand();
cmd.CommandText = sql;
cmd.Parameters.AddRange(parameter); using (var da = new SqlDataAdapter(cmd))
{
var dt = new DataTable();
var ds = new DataSet();
try
{
da.Fill(ds, "ds");
if (ds.Tables.Count <= 0)
return null;
dt = ds.Tables[0]; cmd.Parameters.Clear();
}
catch (SqlException ex)
{
throw new Exception(ex.Message);
}
return dt;
}
}
catch (Exception ex)
{
throw new Exception(ex.ToString() + " " + sql);
}
}
#endregion
第二种返回的DateSet：
#region //执行查询语句，返回DataSet
/// <summary>
/// 执行查询语句，返回DataSet
/// </summary>
/// <param name="sqlString">查询语句</param>
/// <param name="cmdParms"></param>
/// <returns>DataSet</returns>
public DataSet GetDataSet(string sql, params SqlParameter[] parameter)
{
using (var connection = new SqlConnection(connectionString))
{
conn.Open();
SqlCommand cmd = conn.CreateCommand();
cmd.CommandText = sql;
cmd.Parameters.AddRange(parameter); using (var da = new SqlDataAdapter(cmd))
{
var ds = new DataSet();
try
{
da.Fill(ds, "ds");
cmd.Parameters.Clear();
}
catch (SqlException ex)
{
throw new Exception(ex.Message);
}
return ds;
}
}
}
#endregion
最新文章
- angular作用域分析
- jQuery 遍历 - find() 方法
- mysql集群之MYSQL CLUSTER
- 使用percona xtradb cluster的IST方式添加新节点
- [Ruby01]Class, Module, Object,Kernel的关系
- [React] React Fundamentals: Component Lifecycle - Updating
- IE6下jquery ajax报error的原因
- 疑问：关于postgres的to_number()
- Python 项目实践二（下载数据）第三篇
- dblink实现不同用户之间的数据表访问
- git常用命令--转载
- 详解spl_autoload_register()  函数（转）
- js中创建命名空间的几种写法
- semantic-ui 模态窗口
- python 多线程小方法
- PAT A1138 Postorder Traversal （25 分）——大树的遍历
- web 常用颜色
- Camstar :新加的modeling对象没有在 modeling的下拉框中显示
- sequelize初使用
- hdu-1133