SqlConnection conn = new SqlConnection("server=10.126.64.11;user=it_oper;pwd=IT@SME2018;database=MESOtheata;"); conn.Open(); SqlCommand cmd = new SqlCommand("select * from [A_Emp_Dept_20190522]", conn);// 或者 //或者 SqlCommand cmd=conn.CreateCommand();cmd.CommandText=""; SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);//读取完毕自动关闭连接 for (int i = 0; i < reader.FieldCount - 1; i++) { Console.WriteLine(reader.GetName(i));//获取字段名 while (reader.Read())//或者使用reader.HasRows属性判断时候有记录 { Console.WriteLine(reader.GetDateTime(0).ToString()); //或者 Console.WriteLine(Convert.ToDateTime(reader[0]).ToString()); object[] values = new object[reader.FieldCount - 1]; reader.GetValues(values);//读取一行所有字段的内容到Values字段中 if (reader.IsDBNull(0) { //判断某字段是否为null值。 } } } reader.Close(); //系统未关闭时,本Command更改CommandText后或新建Command还有继续使用此连接。 //conn.Close();
1、使用SQLClient:
SqlCommand cmd = new SqlCommand("select * from [A_Emp_Dept_20190522] where empname=@empname", conn); SqlParameter para = new SqlParameter("@empname", SqlDbType.NVarChar, 10); para.Value = "曾亮"; cmd.Parameters.Add(para); //或者直接 cmd.Parameters.AddWithValue("@empname","曾亮");
2、使用OleDb:
OleDbCommand cmd = new OleDbCommand("select * from [A_Emp_Dept_20190522] where empname like ? and line like ?", conn); cmd.Parameters.AddWithValue("@empname", "曾亮"); cmd.Parameters.AddWithValue("@line", "ODMZ%");//参加的参数的顺序应与?号的顺序相同,参数名可随意执行,甚至可以是空串。
SqlCommand cmd = new SqlCommand("update [A_Emp_Dept_20190522] set dept='aa' where dept='' ", conn); int RecordAffected = cmd.ExecuteNonQuery(); if (RecordAffected == 0) { Console.Write("操作失败"); }
SqlCommand cmd = new SqlCommand("select count(*) from [A_Emp_Dept_20190522] ", conn); if (Convert.ToInt32(cmd.ExecuteScalar()) == 0)//无记录,返回null { Console.Write("无记录"); }
SqlTransaction trans = null; try { trans = conn.BeginTransaction();//默认事务隔离级别为ISolationLevel.Serilizable,Oracle为ISolationLevel.ReadCommited SqlCommand cmd = new SqlCommand("Insert int **", conn); cmd.Transaction = trans;//为命令指定一个事务 cmd.ExecuteNonQuery(); //可以有多个SqlCommand一并执行,一起提交或回滚 trans.Commit(); } catch { trans.Rollback(); }
Transaction事务隔离级别:
SqlCommand cmd = new SqlCommand("GetCustomer", conn); cmd.CommandType = CommandType.StoredProcedure; SqlParameter para1 = new SqlParameter("@CustomerID", SqlDbType.NChar, 10); para1.Value = "UINET"; cmd.Parameters.Add(para1); SqlParameter para2 = new SqlParameter("@CompanyName", SqlDbType.NVarChar, 30); para2.Direction = ParameterDirection.Output; cmd.Parameters.Add(para2); cmd.ExecuteNonQuery(); Console.WriteLine(cmd.Parameters["@CompanyName"].Value);
SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.SchemaOnly);//仅仅读取模式信息 DataTable table = reader.GetSchemaTable(); foreach (DataRow row in table.Rows) { foreach (DataColumn col in table.Columns) { Console.WriteLine(col.ColumnName + row[col.ColumnName]); } }
SqlCommand cmd = new SqlCommand("select * from Catogories;select * from Customers", conn); SqlDataReader reader = cmd.ExecuteReader();//仅仅读取模式信息 DataTable table = reader.GetSchemaTable(); do//首先自动定位在第一个结果集上 { while (reader.Read()) { Console.Write(reader[0]); } } while (reader.NextResult());
从数据源中读取行的只进流,包含SqlDataReader ,OleDbDataReader ,OdbcDataReader ,实现了IDataReader IDataRecord 接口
到此这篇关于C#SQLCommand命令与DbTransaction事务处理的文章就介绍到这了。希望对大家的学习有所帮助,也希望大家多多支持。