C# 封装的DBHelper
内容不全，以后会添加。
C#与 SQL 链接。
1.链接字符串配置信息保存于App.config中
<!--连接数据库字符串-->
<connectionStrings>
<add name="DBStrConn" connectionString="Data Source=.; initial Catalog=数据库; user id=用户名; password=密码"/>
</connectionStrings>
2.添加 System.configuration 引用
3.在DBHelper中获取链接字符串
/* * 获取连接数据库字符串 * 此字符串存在App.config应用配置文件中 */ private static string strConnection = ConfigurationManager.ConnectionStrings["DBStrConn"].ConnectionString; //DBStrConn为在App.config中的"name"名
4.1 ExecuteNonQuery方法执行 插入、修改、删除
public static int ToInUpDel_ExecuteNonQuery(string sql)
{
//连接命令
using (SqlConnection conn = new SqlConnection(strConnection))
{
conn.Open(); //打开连接
using (SqlCommand cmd = conn.CreateCommand())
{
//执行sql语句
cmd.CommandText = sql;
//返回受影响的行数
return cmd.ExecuteNonQuery();
}
}
}
4.2 ExecuteScalar方法 执行 查询
public static int ToSelect_ExecuteScalar(string sql)
{
using (SqlConnection conn = new SqlConnection(strConnection))
{
conn.Open();
using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = sql;
//返回结果
return (int)cmd.ExecuteScalar();
}
}
}
4.3 DataTable 用来查询结果比较少的sql
public static DataTable ExecuteDataTable(string sql)
{
using (SqlConnection conn = new SqlConnection(strConnection))
{
conn.Open();
using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = sql;
SqlDataAdapter adapter = new SqlDataAdapter(cmd);
DataSet dataset = new DataSet();
adapter.Fill(dataset);
return dataset.Tables[0];
}
}
}
4.4 SqlDataReader 需要手动关闭
public static SqlDataReader ExecuteReader(string sql)
{
SqlConnection conn = new SqlConnection(strConnection);
SqlCommand cmd = new SqlCommand(sql,conn);
try
{
conn.Open();
SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection); //CommandBehavior.CloseConnection 在关闭DataReader的时候自动关闭Connection
return reader;
}
catch(SqlException ex)
{
throw ex;
}
}
-------------------------------------------分割线-----------------------------------------------
---------------------------------------以下是修改的--------------------------------------------
-----------------------------------修改时间：2015.3.2----------------------------------------
5.1 执行insert\update\delete 带参数
public static int ExecuteNonQuery(string sql, CommandType cmdType, params SqlParameter[] pms)
{
using (SqlConnection conn = new SqlConnection(connStr))
{
using (SqlCommand cmd = new SqlCommand(sql, conn))
{
cmd.CommandType = cmdType; //设置当前执行的是存储过程还是带参数的sql语句
if (pms != null)
{
cmd.Parameters.AddRange(pms);
}
conn.Open();
return cmd.ExecuteNonQuery();
}
}
}
5.2 执行select(执行返回单个值的方法) 带参数
public static object ExecuteScalar(string sql, CommandType cmdType, params SqlParameter[] pms)
{
using (SqlConnection conn = new SqlConnection(connStr))
{
using (SqlCommand cmd = new SqlCommand(sql, conn))
{
cmd.CommandType = cmdType;
if (pms != null)
{
cmd.Parameters.AddRange(pms);
}
conn.Open();
return cmd.ExecuteScalar();
}
}
}
5.3 返回SqlDataReader的方法 带参数
public static SqlDataReader ExecuteReader(string sql, CommandType cmdType, params SqlParameter[] pms)
{
SqlConnection conn = new SqlConnection(connStr);
using (SqlCommand cmd = new SqlCommand(sql, conn))
{
cmd.CommandType = cmdType;
if (pms != null)
{
cmd.Parameters.AddRange(pms);
}
try
{
conn.Open();
return cmd.ExecuteReader(CommandBehavior.CloseConnection);
}
catch
{
conn.Close();
conn.Dispose();
throw;
}
}
}
5.4 返回DataTable的方法 带参数
public static DataTable ExecuteDataTable(string sql, CommandType cmdType, params SqlParameter[] pms)
{
DataTable dt = new DataTable();
using (SqlDataAdapter adapter = new SqlDataAdapter(sql, connStr))
{
adapter.SelectCommand.CommandType = cmdType;
if (pms != null)
{
adapter.SelectCommand.Parameters.AddRange(pms);
}
adapter.Fill(dt);
return dt;
}
}