C#中连接数据库的方式

Sql Sever数据库

1.连接本地数据库（Windows验证登录方式）
string constr = “server=本地服务器;Initial Catalog=数据库名称;Integrated Security=True”;
Windows验证登录方式以SQLSever2008R2为例，如图所示

2.连接sa账户（SQL Server验证登录方式）
string constr = “Data Source =服务器;Initial Catalog=数据库名称;User Id=登录名;Password=密码”;
SQL Server验证：SQLSever2008R2为例，如图所示

实现数据库连接的C#代码如下：
1.方法1：连接数据库，返回DataTable的数据

class Sqlconnn{private static string constr = "server=.;Initial Catalog=D_total;Integrated Security=True";//本地数据库// private static string constr = "Data Source =192.168.1.200;Initial Catalog=D_total ;User Id=sa;Password=123456";//sa账户public DataTable f1()//应用实例{string A = "select * from user";return Conn(A);}//连接数据库，返回DataTable数据--用于查询public DataTable Conn(string exec){System.Data.DataTable dt_jdl = new DataTable();try{using (SqlConnection con = new SqlConnection(constr)){if (con.State == ConnectionState.Closed){con.Open();} if (con.State == ConnectionState.Open || con.State == ConnectionState.Connecting){SqlDataAdapter sda2 = new SqlDataAdapter(exec, con);//全部通過寫存儲過程即可DataSet ds2 = new DataSet();sda2.Fill(ds2, "cxq");dt_jdl = ds2.Tables["cxq"];sda2.Dispose();ds2.Dispose();}con.Close();}return dt_jdl;}catch (Exception EX){return null;}}//通用的增删改public static int excuteNoQuery(string sql){int count=0;try{using (SqlConnection con = new SqlConnection(constr)){if (con.State == ConnectionState.Closed){con.Open();} if (con.State == ConnectionState.Open || con.State == ConnectionState.Connecting){//创建命令对象SqlCommand cmd = new SqlCommand(sql, con);count = cmd.ExecuteNonQuery();cmd.Dispose();}con.Close();}return count;}catch (Exception EX){return 0;}         }   }

2.方法2：连接数据库方法

 class SqlCon{#region 全局变量//定义一个SqlConnection类型的静态公共变量My_con，用于判断数据库是否连接成功public static SqlConnection My_con;//定义数据库连接字符串public static string Str_sqlcon1 = "server=(local);Initial Catalog=D_total;Integrated Security=True";public static string Str_sqlcon2 = "Data Source=.;Database=D_total;Userid=sa;PWD=123";public static string Str_sqlcon3 = "Data Source =192.168.1.200;Initial Catalog=D_total ;User Id=sa;Password=123";#endregion/// <summary>/// 建立数据库连接/// </summary>/// <returns></returns>public static SqlConnection getcon(){My_con = new SqlConnection(Str_sqlcon1);//用SqlConnection对象与指定的数据库相连接  My_con.Open();//打开数据库连接return My_con;//返回SqlConnection对象信息}/// <summary>/// 关闭数据库连接/// </summary>public void con_close(){if (My_con.State == ConnectionState.Open)//判断是否打开与数据库的连接{My_con.Close();//关闭数据库的连接My_con.Dispose();//释放My_con变量的所有空间}}/// <summary>/// 以只读方式读取数据库信息/// </summary>/// <param name="SQLstr">表示传递的SQL语句</param>/// <returns></returns>public SqlDataReader getcom(string SQLstr){getcon();//打开数据库连接SqlCommand My_com = My_con.CreateCommand();//创建SqlConnection对象，用于执行SQL语句My_com.CommandText = SQLstr;//获取指定的SQL语句SqlDataReader My_read = My_com.ExecuteReader();//执行SQL语句，生成一个SqlDataReader对象return My_read;}/// <summary>/// 通过SqlCommand对象执行数据库中的添加、修改和删除操作/// </summary>/// <param name="SQLstr">表示传递的SQL语句</param>public void getsqlcom(string SQLstr){getcon();//打开数据库连接SqlCommand SQLcom = new SqlCommand(SQLstr, My_con);//创建SqlConnection对象，用于执行SQL语句SQLcom.ExecuteNonQuery();//执行SQL语句SQLcom.Dispose();//释放所有空间con_close();//关闭数据库连接}      /// <summary>/// 通过SqlCommand对象执行数据库中的添加、修改和删除操作/// </summary>/// <param name="SQLstr">传递的SQL语句</param>/// <param name="tableName"></param>/// <returns>DataSet</returns>public DataSet getDataSet(string SQLstr, string tableName){getcon();//打开数据库连接SqlDataAdapter SQLda = new SqlDataAdapter(SQLstr, My_con);DataSet ds = new DataSet();//创建DataSet对象SQLda.Fill(ds, tableName);con_close();//关闭数据库连接return ds;//返回DataSet对象信息}/// <summary>/// 通过SqlCommand对象执行数据库中的添加、修改和删除操作/// </summary>/// <param name="SQLstr">传递的SQL语句</param>/// <param name="tableName"></param>/// <returns>DataTable</returns>public DataTable  getDataTable(string SQLstr, string tableName){DataTable dt = new DataTable();getcon();//打开数据库连接SqlDataAdapter SQLda = new SqlDataAdapter(SQLstr, My_con);DataSet ds = new DataSet();SQLda.Fill(ds, tableName);dt = ds.Tables[tableName];con_close();//关闭数据库连接return dt;//返回DataSet对象信息}}

Qracle数据库

以Oracle.ManagedDataAccess.dll方式连接Qracle数据库服务器，亲测可用
参考链接：https://www.cnblogs.com/youguess/p/9854408.html
连接字符串： private static string connStr = “User Id=使用者名称;Password=密码;Data Source=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=主机名称)(PORT=端口号)))(CONNECT_DATA=(SERVICE_NAME=服务器名称)))”;
说明：其中User Id为使用者名称；Password为密码；HOST为主机名称；PORT为端口号；SERVICE_NAME为服务器名称
这些根据个人数据库修改

1.dll下载：https://files.cnblogs.com/yjmyzz/Oracle.ManagedDataAccess.zip
2.可以直接添加引用
3.使用代码：

 /// <summary>/// oracle数据库基础类/// </summary>     public  class OracleHepler{ private static string connStr = "User Id=ae_re;Password=123;Data Source=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=10.3.12.202)(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=PACKSTB)))";#region 执行SQL语句,返回受影响行数public static int ExecuteNonQuery(string sql, params OracleParameter[] parameters){using (OracleConnection conn = new OracleConnection(connStr)){conn.Open();using (OracleCommand cmd = conn.CreateCommand()){cmd.CommandText = sql;cmd.Parameters.AddRange(parameters);return cmd.ExecuteNonQuery();}}}#endregion#region 执行SQL语句,返回DataTable;只用来执行查询结果比较少的情况public static DataTable ExecuteDataTable(string sql, params OracleParameter[] parameters){using (OracleConnection conn = new OracleConnection(connStr)){conn.Open();using (OracleCommand cmd = conn.CreateCommand()){cmd.CommandText = sql;cmd.Parameters.AddRange(parameters);OracleDataAdapter adapter = new OracleDataAdapter(cmd);DataTable datatable = new DataTable();adapter.Fill(datatable);return datatable;}}}#endregion}   private void button1_Click(object sender, EventArgs e)//winform程式：里面一个button和一个dataGridView{string sqlString = "select * from (select * from scqhp.cell_sort_info_by_customer) where ROWNUM<=10 ORDER BY ROWNUM asc";DataTable dt = OracleHepler.ExecuteDataTable(sqlString, new OracleParameter());dataGridView1.DataSource = dt;}