How to build a dynamic query with values from a search form in Access
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This article applies to either a Microsoft Access database (.mdb) file or to a Microsoft Access database (.accdb) file, and to a Microsoft Access project (.adp) file.
This article shows you how to dynamically build criteria for a query string with values from a search form in Microsoft Access.
Sometimes, you may want to create a form that serves as a search form. You want to be able to enter values on the form and dynamically build the appropriate SQL string. The following steps show you how to dynamically build a query string that uses the BuildCriteria method.
Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements.CAUTION: If you follow the steps in this example, you modify the sample database Northwind.mdb. You may want to back up the Northwind.mdb file and follow these steps on a copy of the database.
- Start Access.
- On the Help menu, point to Sample Databases, and then click Northwind Sample Database.
- Open the Customers form in Design view.
- Add a command button and a text box to the form, and then set the following properties:
Command Button ------------------------ Name: cmdSearch Caption: Search OnClick: Event Procedure Text Box -------------- Name: txtSQL Width: 4.4583" Height: 1.25"
- Set the OnClick property of the command button to the following event procedure:
Private Sub cmdSearch_Click() On Error Resume Next Dim ctl As Control Dim sSQL As String Dim sWhereClause As String 'Initialize the Where Clause variable. sWhereClause = " Where " 'Start the first part of the select statement. sSQL = "select * from customers " 'Loop through each control on the form to get its value. For Each ctl In Me.Controls With ctl 'The only Control you are using is the text box. 'However, you can add as many types of controls as you want. Select Case .ControlType Case acTextBox .SetFocus 'This is the function that actually builds 'the clause. If sWhereClause = " Where " Then sWhereClause = sWhereClause & BuildCriteria(.Name, dbtext, .Text) Else sWhereClause = sWhereClause & " and " & BuildCriteria(.Name, dbtext, .Text) End If End Select End With Next ctl 'Set the forms recordsource equal to the new 'select statement. Me.txtSQL = sSQL & sWhereClause Me.RecordSource = sSQL & sWhereClause Me.Requery End Sub
Save the form, and then open it in Form view.
Note that when you click the Search command button, the txtSQL text box reflects the query that was created from the values on the Customers form. Also, the Customers form has been requeried so that it reflects the results of the new SQL string.
For more information about the BuildCriteria method, in the Visual Basic Editor, click Microsoft Visual Basic Help on the Help menu, type buildcriteria method in the Office Assistant or the Answer Wizard, and then click Search to view the topic.