c# combobox fill from database

To get only the unique /distinct/ data table records from any database connected to DataSet in C# project and to put them inside combobox.Fill the table adapter with the records from database.
this.myDBTable_TableAdapter.Fill(this.myDB_DataSet.myDBTable);
Create a view containing the database table
DataView view = new DataView(this.myDB_DataSet.myDBTable);

Copy only the distinct records to new data table.
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2017/10/05 03:18

Get latest date record - SQL query

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To return the latest record (one record only) from data base table where one of the fields is in Date/Time format:
SELECT TOP 1 * FROM table_name ORDER BY date_time_column_name DESC
Notes:
  • for ORACLE instead of TOP 1,  ROWNUM shall be used
  • the query may return NULL value - suitable exception handling must be provided
2017/10/05 03:02

c# combobox set selected item by item's text

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C# Combobox defined with name my_combobox
private System.Windows.Forms.ComboBox my_combobox;

Define string variable with the text of the combobox item that has to be selected. For example, if the combobox items have text values "item_a" "item_b" "item_c" ... and the item which text is "item_b" has to be selected
2017/10/05 02:52

C# - Get database connection string from Web.config file

To get the database connection string from IIS Web.config file using C# code, include System.Configuration directive and then create a string variable to assign the connection string like this:
using System.Configuration;
string connStr = ConfigurationManager.
                  ConnectionStrings["connectionString_Name"].ConnectionString;

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2017/10/05 02:45

C# Textbox - enter only positive numbers on KeyPress event in Windows form application

To prevent users from entering incorrect data in Windows form application, set restriction to allow only specific characters to be entered in the text box.This example uses KeyPress event to monitor the users input and to apply the restriction required.To avoid code duplication in Windows multiform applications for example, a separate class file is created “CommonFunctions.cs”.
The function to allow only numbers in textbox control is named InputNumbers.
For each Windows form, create a single KeyPress event and call the InputNumbers function inside it.
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2017/10/05 02:27

c# passing data between forms

C# project with two forms
public partial class Form1 : Form // this is the main form

public partial class Form2 : Form // this is the second form
To pass variables (values, data) from Form1 to Form2
Case: public variables in Form2
public string input_variable; // put this in Form2 as global variable

public string output_variable; // put this in Form2 as global variable

in Form1 inside the function that run (call) Form2
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2017/10/05 02:07