Member Avatar for Amiet_1

I have DatagridView on form.

My database has three fields.
- userId (bigint)
- userName (varchar)
- userDob (date)

Now, on Form I have comboBox, which lists Months (Jan, Feb, March and so on...). I want my program to work like this.

If I select any month on ComboBox, birthdays of clients related to that month should only be displayed in DatagridView. Help me how to do it.

Edited by Amiet_1
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  • Latest Post Latest Post by djjeavons

Dani AI

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As requested, the goal is to show only rows whose DOB falls in the selected month. Both and are on the right track: filtering by month is the correct idea. A more robust pattern is to pass the month as a parameter from the ComboBox and let the SQL compare the month number (not a formatted string). This avoids localization/formatting pitfalls and eliminates string concatenation (safer and immune to injection).

Example VB.NET pattern (WinForms, SqlClient):

Imports System.Data.SqlClient

Private Sub cbMonth_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cbMonth.SelectedIndexChanged
    Dim monthNumber As Integer = cbMonth.SelectedIndex + 1   ' assumes items Jan..Dec in order
    LoadBirthdays(monthNumber)
End Sub

Private Sub LoadBirthdays(monthNumber As Integer)
    Dim sql As String =
        "SELECT userId, userName, userDob " &
        "FROM Users " &
        "WHERE MONTH(userDob) = @month " &
        "ORDER BY DATEPART(day, userDob)"

    Using cn As New SqlConnection(connectionString)
        Using cmd As New SqlCommand(sql, cn)
            cmd.Parameters.Add("@month", SqlDbType.TinyInt).Value = monthNumber
            Dim da As New SqlDataAdapter(cmd)
            Dim dt As New DataTable()
            da.Fill(dt)
            DataGridView1.DataSource = dt
        End Using
    End Using
End Sub

Notes and troubleshooting:

  • If userDob can be NULL, add an appropriate NULL check in the WHERE clause.
  • For large tables, applying a function to a column (MONTH(userDob)) prevents use of a plain index. Consider adding a computed, persisted month column and index it for performance:
ALTER TABLE Users ADD userDobMonth AS MONTH(userDob) PERSISTED;
CREATE INDEX IX_Users_userDobMonth ON Users(userDobMonth);
  • If the ComboBox is populated with month names, map names to numbers reliably (SelectedIndex+1 is simplest when months are listed in order). For non‑SQL Server backends the function name may differ (e.g., EXTRACT/MONTH equivalents).

Recommended Answers

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Member Avatar for JerrimePatient

add this to your query.

where userDob like '"+cbYear.Text+"-"+cbMonth.Text+"-%' order by userDob

example output: `where userDob like '2015-01-%' order by userDob`

the format of date is `yyyy-MM-dd`:


for `yyyy` represent 4 digit year.
    `MM` represent 2 digit month.
    `dd` represent 2 digit day.



Happy Programming and God Bless you.
Edited by JerrimePatient
Member Avatar for djjeavons

If this is SQL Server then you could use the DATENAME method:

SELECT * FROM YourTable where DATENAME(month, YourDateField) = 'July'

In this way, you can select all records that match a month regardless of year which is what I believe you want.

commented: May be this will solve my problem... I'll try this code ASAP +0
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