From Xojo Documentation

You are currently browsing the old Xojo documentation site. Please visit the new Xojo documentation site!

Class (inherits from DatabaseColumn)

Used to access the values of fields in a record in a database table.

BooleanValue Int64Value PictureValue
CurrencyValue IntegerValue StringValue
DateValue Name fa-lock-32.png Value
DoubleValue NativeValue fa-lock-32.png
GetString SetString


Assignments to the DateValue property store the time as well as the date, as with DatabaseRecords. When getting a value, the resulting Date object may contain a time as well as a date. For fields of type Date, the time will be 00:00:00 (midnight); and for fields of type Time, the date will be January 1, 0001. Fields of type TimeStamp contain valid data for both the date and time.

Boolean fields are strict about what they expect when using the BooleanValue function: "0" and "False" are treated as False and "1" and "True" are treated as True. The behavior of any other values is undefined when retrieved using BooleanValue. The StringValue property, on the other hand, should be able to retrieve the original data if it can't be identified as a Boolean.

The conversion operator, Operator_Convert, has been added to StringValue, BooleanValue, DateValue, IntegerValue, and DoubleValue.

Typically you should use the type-specific "Value" properties to get and set values from the database.

NULL Columns

The properties that return intrinsic value types (Boolean, Currency, Double, Int64, Integer, String) all return their appropriate default value if the database column is NULL.

To check if a column is NULL, use the Value property like this:

If rs.Field("MyColumn").Value Is Nil Then
// Column value is NULL
End If

For situations where you need to set a database column to NULL, you should use the Value property like this:

rs.Field("MyColumn").Value = Nil // sets to NULL in the database

Sample Code

The following method populates a ListBox with a RecordSet. It uses the Name and StringValue properties to obtain the fieldnames and values:

Sub PopulateListBox(dataList As Listbox, rs As RecordSet)
If rs Is Nil Then Return

// set up listbox state for population
dataList.Columncount = rs.Fieldcount

// Add the DB columns as the heades for the ListBox
dataList.ColumnCount = rs.FieldCount
dataList.Column(-1).WidthExpression = "100"
For i As Integer = 0 To rs.FieldCount - 1
dataList.Heading(i) = rs.IdxField(i + 1).Name

// Add the data from the table
While Not rs.EOF

For i As Integer = 0 To rs.FieldCount - 1
dataList.Cell(dataList.LastIndex, i) = rs.IdxField(i + 1).StringValue

End Sub

The following code uses the Value property to set the values of fields of different data types.

Dim myDB As RealSQLDatabase
Dim rs As RecordSet
rs = myDB.SQLSelect("SELECT * FROM MyTable")
rs.Field("MyName").Value = Nil // NULL this field, does not work for all database plugins
rs.Field("MyID").Value = 23
rs.Field("MyText").Value = "Test"
If Not myDB.Error Then
MsgBox("Error: " + myDB.ErrorMessage)
End If

See Also

Database, DatabaseRecord, RecordSet classes.