我想如何检查数据库是否找到了输入的数据 [英] i want how to check the database whether the entered data is found or not

问题描述

我在表中有某些数据..im在表中有国家/地区名称和国家/地区名称作为列名...我想在Web应用程序中使用示例C#编码..这个概念是我必须检查该国家/地区的名称和ID必须在前端进行检查

im having certain data in the table..im having country id and country name as column name in table...i want sample C# coding in web application..the concept is that i have to check that country name and id has to checked in front end

推荐答案

最好在SQL本身中进行处理.将列国家/地区名称作为唯一键.将您的Insert查询放入try catch中这样的SQL，

开始尝试
开始
INSERT查询
结束
结束尝试

开始捕捉
如果ERROR_NUMBER()= 2601-重复记录
开始
SELECT -1
END
结束观看


在前端检查返回值是否为-1.如果为-1，则给出相应的错误消息

It is better to handle it in SQL itself.Make columns Country name as Unique key.Put your Insert query inside a try catch in SQL like this,

BEGIN TRY
BEGIN
INSERT query
END
END TRY

BEGIN CATCH
IF ERROR_NUMBER()=2601 -- Duplicate Record
BEGIN
SELECT -1
END
END CATCH


In frontend , check whether the return value is -1 .If it is -1 give the corresponding error message

您需要从前端编写查询……查询包含count函数，并在前端使用execute标量函数执行该查询.

例如:
str =从表名中选择count(*)"
cmd.Executescalar()

you need to write a query from front end......query contains count function and execute that query using execute scalar function in front end.

For example :
str = "select count(*) from table_name"
cmd.Executescalar()

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