将文本框值与数据库字段进行比较 [英] Comparing textbox value with database field

问题描述

大家好



如何将用户输入的文本框值与数据库中的字段进行比较，以检查该值是否存在？我希望用户输入一个条形码，然后系统检查该bacode是否存在 - 用户可以根据结果进行任务处理。



谢谢。

解决方案

首先，您必须建立与数据库的连接。根据数据库的类型，您可以运行类似于/ b

  SELECT  *的SQL查询 FROM  tblBarcodes  WHERE 条形码= '  1234567890' 

我们需要有关用于协助此类连接的数据库的更多信息。也是网络上的数据库，或者它是否在本地PC上运行。

这是算法：



1。读取文本框值

2.将值发送到数据库，使用存储过程执行以下查询以检查值是否存在：

 声明  @ itexists   as   int ; 
 
 如果 存在（选择 * 来自 MyTable 其中条形码= @条形码）
  set  @ itexists = 1; 
  else  
  set  @ itexists = 0; 
 
  print   @ itexists ; 

3.使用ExecuteScalar获取结果并根据此值执行其余操作





在你的情况下。只需修改您的数据库代码如下：

  public   bool  CompareBarcode（ string 条形码）
 {
 使用（SqlConnection conn =  new  SqlConnection（ConnectionSTring））
 {
 SqlCommand cmd =  new  SqlCommand（  uspCheckBarcode，conn）; 
 cmd .CommandType = CommandType.StoredProcedure; 
 cmd.Parameters.AddWithValue（  @ barcode，条形码）; 
  return  Convert.ToBoolean（cmd.ExecuteScalar（））; 
 
} 
 

我正在使用SQL Server数据库..我创建了一个存储过程（SELECT Barcode FROM Equipment条形码= @barcode）

-当我执行该查询并输入已注册的条形码时，它会返回它，然后当我输入未注册的条形码时它不会返回任何内容。



>>>数据访问层

 public DataTable CompareBarcode（字符串条形码）
 {
 using（SqlConnection） conn = new SqlConnection（ConnectionSTring））
 {
 
 DataTable dtBarcode = new DataTable（）; 
 SqlCommand cmd = new SqlCommand（uspCheckBarcode'+ barcode +'，conn）; 
 dbAdapter = new SqlDataAdapter（cmd）; 
 dbAdapter.Fill（dtBarcode）; 
返回dtBarcode; 
 
} 
 

>>>演示层

  private   void  txtInputBarcode_TextChanged（ object  sender ，EventArgs e）
 {
  //  检查用户输入的条形码是否已注册，通过检查来自数据库 
 
 BusinessObject bo =  new  BusinessObject（）; 
 bo.CompareBarcode（txtInputBarcode.Text）; 
 
  //   lblBarcodeResult.Text =条形码注册;  
 
 
 
  //   lblBarcodeResult.Text =条形码未注册;  
 
} 

我需要一个if语句来检查是否有条形码，并返回一条lblresult消息

Hi All

How can I go about comparing a textbox value inputted by a user, with a field in a database to check whether that value exists? I want the user to enter a barcode , and the system to check whether that bacode exists or not-and the user may procceed with a task,depending on the result.

Thanks.

解决方案

Firstly you will have to make a connection to the database. Depending on the type of database it is you can then run a SQL query someting similar to

SELECT * FROM tblBarcodes WHERE Barcode = '1234567890'

We will need more information on the database being used to assist with such connection. Also is the database on a network or is it running on the local PC.

Here is the algorithm:

1. Read the textbox value
2. Send the value to database, using stored procedure execute the below query to check whether the values exist or not:

declare @itexists as int;

if exists(select * from MyTable where Barcode=@barcode)
    set @itexists=1;
else
    set @itexists=0;

print @itexists;

3. Get the result using ExecuteScalar and perform rest of the operations based on this value


In your case. just modify your database code as below:

public bool CompareBarcode(string barcode)
       {
           using (SqlConnection conn = new SqlConnection(ConnectionSTring))
           {
               SqlCommand cmd = new SqlCommand("uspCheckBarcode", conn);
               cmd .CommandType = CommandType.StoredProcedure;
               cmd.Parameters.AddWithValue("@barcode", barcode);
               return Convert.ToBoolean(cmd.ExecuteScalar());

           }

I am using an SQL Server database.. I created a stored procedure ( SELECT Barcode FROM Equipment WHERE barcode = @barcode)
-when I execute that query and type a registered barcode,it returns it and then when i type an unregistered barcode it doesnt return anything.

>>>Data Access layer

public DataTable CompareBarcode(string barcode)
       {
           using (SqlConnection conn = new SqlConnection(ConnectionSTring))
           {

               DataTable dtBarcode = new DataTable();
               SqlCommand cmd = new SqlCommand("uspCheckBarcode'" + barcode + "'", conn);
               dbAdapter = new SqlDataAdapter(cmd);
               dbAdapter.Fill(dtBarcode);
               return dtBarcode;

           }

>>>Presentation layer

private void txtInputBarcode_TextChanged(object sender, EventArgs e)
       {
           //checks whether barcode entered by user is registered, by checking from the database

               BusinessObject bo = new BusinessObject();
               bo.CompareBarcode(txtInputBarcode.Text);

               //lblBarcodeResult.Text = "Barcode registered";



               //lblBarcodeResult.Text = "Barcode is not registered";

       }

I need an "if" statement that's going to check whether barcode,and return one of the lblresult messages

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