如果表中已存在数据（Ado.net）

本文介绍了如果表中已存在数据（Ado）的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

以下是使用Ado存储过程在表格中插入行的代码。

Here is the code for inserting rows in a table using Ado stored procedure.

<pre lang="c#"> IDbConnection conn = null; try { conn = this.GetConnection(); conn.Open(); IDbCommand cmd = conn.CreateCommand(); //string insertSQL = @"insert into Routes(FromCityId,ToCityId,DistanceInKms,Status) values(@fromcityID,@toCityID,@dis,@st);"; //cmd.CommandText = insertSQL; //cmd.CommandType = CommandType.Text; cmd.CommandText = "StoredProcedureName"; cmd.CommandType = CommandType.StoredProcedure; IDataParameter p1 = cmd.CreateParameter(); p1.ParameterName = "@FromCity"; p1.Value = RouteInfo.FromCity.CityId; cmd.Parameters.Add(p1); //........................ return cmd.ExecuteNonQuery(); } } catch (Common.ConnectToDatabaseException) { throw new RouteDAOException("Unable to add route"); } catch (Exception) { throw new RouteDAOException("Unable to add route"); } finally { conn.Close(); }

我需要提示写一个代码来检查行是否是已存在，如果是，我将不得不创建一个例外。 最好的问候，

I need a hint to write a code for checking if the row is already exists , if yes , I will have to create an exception. best regards,

推荐答案

在存储过程中使用以下IF语法 use following IF syntax in the stored procedure IF NOT EXISTS(SELECT * FROM TABLE NAME WHERE <duplicate condition="">) BEING --INSERT INTO TABLENAME (columnName1,..) VALUES (...) END </duplicate>

您需要在Sql中检查它。 在SQL中你做 You will want to check for it in Sql. In SQL you do IF EXISTS(SELECT * FROM table WHERE field = value) BEGIN -- do an update since it exists UPDATE table SET field1 = value. field2 = value2 WHERE field = value END ELSE BEGIN -- Since it does not exist, do an insert INSERT INTO ... END