Class

DatabaseColumn

Description

Used to access the values of columns in a row in a database table.

Properties

Name	Type	Read-Only
BlobValue	String
BooleanValue	Boolean
CurrencyValue	Currency
DateTimeValue	DateTime
DoubleValue	Double
Int64Value	Int64
IntegerValue	Integer
Name	String	✓
NativeValue	String	✓
PictureValue	Picture	✓
StringValue	String
Type	Integer	✓
Value	Variant

Methods

Name	Parameters	Returns	Shared
PictureValue	format As Picture.Formats, quality As Integer = Picture.QualityDefault, Assigns value As Picture

Property descriptions

DatabaseColumn.BlobValue

BlobValue As String

Used to get and set the values of Blob (Binary Large OBject) field types.

If the field is not of this type, BlobValue will try to return the value as a String. SQLiteDatabase converts text to UTF-8 text encoding.

When using this property to assign binary data, no encoding is added.

DatabaseColumn.BooleanValue

BooleanValue As Boolean

Used to get and set the values of Boolean field types.

The values 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. Use StringValue to retrieve the original values in the field.

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

rs.EditRow
rs.Column("MyBooleanColumn").Value = Nil ' sets to NULL in the database
rs.SaveRow

Get the boolean value of a column in a RowSet:

' rs is a RowSet with a boolean column called "AllowEmails"
If rs.Column("AllowEmails").BooleanValue Then
  MessageBox("Emails are allowed.")
End If

Set the boolean value of a column in a RowSet:

' rs is a RowSet with a boolean column called "AllowEmails":
rs.EditRow
rs.Column("AllowEmails").BooleanValue = True
rs.SaveRow

DatabaseColumn.CurrencyValue

CurrencyValue As Currency

Used to get and set the values of Currency field types.

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

rs.EditRow
rs.Column("MyCurrencyColumn").Value = Nil ' sets to NULL in the database
rs.SaveRow

Get the currency value of a column in a RowSet:

' rs is a RowSet with a currency column called "Amount"
Var amount As Currency
amount = rs.Column("Amount").CurrencyValue

Set the currency value of a column in a RowSet:

' rs is a RowSet with a currency column called "Amount":
rs.EditRow
rs.Column("Amount").CurrencyValue = 123.45
rs.SaveRow

DatabaseColumn.DateTimeValue

DateTimeValue As DateTime

Used to get and set the values of DateTime field types.

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

rs.EditRow
rs.DateTimeColumn("MyDateColumn").Value = Nil ' sets to NULL in the database
rs.SaveRow

Get the date value of a column in a RowSet:

' rs is a RowSet with a date column called "InvoiceDate"
Var invoiceDate As DateTime
invoiceDate = rs.Column("InvoiceDate").DateTimeValue

Set the date value of a column in a RowSet:

' rs is a RowSet with a date column called "InvoiceDate":
rs.EditRow
Var d As DateTime = DateTime.Now
rs.DateTimeColumn("InvoiceDate").DateTime = d
rs.SaveRow

DatabaseColumn.DoubleValue

DoubleValue As Double

Used to get and set the values of Double field types.

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

rs.EditRow
rs.Column("MyDoubleColumn").Value = Nil ' sets to NULL in the database
rs.SaveRow

Get the double value of a column in a RowSet:

' rs is a RowSet with a double column called "InterestRate"
Var interestRate As Double
interestRate = rs.Column("InterestRate").DoubleValue

Set the double value of a column in a RowSet:

' rs is a RowSet with a double column called "InterestRate":
rs.EditRow
rs.Column("InterestRate").DoubleValue = 3.625
rs.SaveRow

DatabaseColumn.Int64Value

Int64Value As Int64

Used to get and set the values of Int64 field types.

Support for 64-bit integers is at the framework level. Database plug-ins need to be updated to support 64-bit integers.

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

rs.EditRow
rs.Column("MyColumn").Value = Nil ' sets to NULL in the database
rs.SaveRow

Get the Int64 value of a column in a RowSet:

' rs is a RowSet with a Int64 column called "ID"
Var id As Int64
id = rs.Column("ID").Int64Value

Set the Int64 value of a column in a RowSet:

' rs is a RowSet with a Int64 column called "ID":
rs.EditRow
rs.Column("ID").Int64Value = 456789
rs.SaveRow

DatabaseColumn.IntegerValue

IntegerValue As Integer

Used to get and set the values of Integer field types.

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

rs.EditRow
rs.Column("MyIntegerColumn").Value = Nil ' sets to NULL in the database
rs.SaveRow

Get the integer value of a column in a RowSet:

' rs is a RowSet with an integer column called "Quantity"
Var quantity As Integer
quantity = rs.Column("Quantity").IntegerValue

Set the integer value of a column in a RowSet:

' rs is a RowSet with an integer column called "Quantity":
rs.EditRow
rs.Column("Quantity").IntegerValue = 3
rs.SaveRow

DatabaseColumn.Name

Name As String

Used to get the name of the column.

This property is read-only.

The following method populates a DesktopListBox with a RowSet. It uses the Name and StringValue properties to obtain the columnnames and values:

Sub PopulateListBox(dataList As DesktopListBox, rs As RowSet)
  If rs Is Nil Then Return

  ' set up listbox state for population
  dataList.RemoveAllRows

    ' Add the DB columns as the heades for the ListBox
    dataList.ColumnCount = rs.ColumnCount
    dataList.ColumnAttributesAt(-1).WidthExpression = "100"
    For i As Integer = 0 To rs.ColumnCount - 1
      dataList.HeaderAt(i) = rs.ColumnAt(i + 1).Name
    Next

    ' Add the data from the table
    While Not rs.AfterLastRow
      dataList.AddRow("")

      For i As Integer = 0 To rs.LastColumnIndex
        dataList.CellTextAt(dataList.LastAddedRowIndex, i) = rs.ColumnAt(i + 1).StringValue
      Next

      rs.MoveToNextRow
    Wend
End Sub

DatabaseColumn.NativeValue

NativeValue As String

Used to get the values of fields in their native encoding. Useful for reading blobs from database fields. Use Value or StringValue to set Blob values in database fields.

This property is read-only.

Get the native value of a column in a RowSet:

' rs is a RowSet with a BLOB column called "FileData"
Var data As String
data = rs.Column("FileData").NativeValue

DatabaseColumn.PictureValue

PictureValue As Picture

Gets the Picture value for the column. To set a picture value, use the method of the same name.

This property is read-only.

DatabaseColumn.StringValue

StringValue As String

Used to get and set the values of String/Character field types.

If the field is not of this type, StringValue will try to return the value as a String. SQLiteDatabase converts text to UTF-8 text encoding.

When using this property to assign binary data, no encoding is added.

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

rs.EditRow
rs.Column("MyStringColumn").Value = Nil ' sets to NULL in the database
rs.SaveRow

Get the string value of a column in a RowSet:

' rs is a RowSet with a string column called "ProductName"
Var productName As String
productName = rs.Column("ProductName").StringValue

Set the string value of a column in a RowSet:

' rs is a Rowset with a string column called "ProductName":
rs.EditRow
rs.Column("ProductName").StringValue = "Generic Widgets"
rs.SaveRow

DatabaseColumn.Type

Type As Integer

Used to get the values of type of a column.

This property is read-only.

See RowSet.ColumnType for a list of integers and their associated types.

DatabaseColumn.Value

Value As Variant

Used to get and set the value of a field of any data type.

The type-specific properties that get and set the values are recommended over Value.

When using this property to assign binary data, no encoding is added.

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

rs.EditRow
rs.Column("MyColumn").Value = Nil ' sets to NULL in the database
rs.SaveRow

Get the double value of a column in a RowSet:

' rs is a RowSet with a double column called "InterestRate"
Var interestRate As Double
interestRate = rs.Column("InterestRate").Value ' Converts from a Variant to a Double

Set the double value of a column in a RowSet:

' rs is a RowSet with a double column called "InterestRate":
rs.EditRow
rs.Column("InterestRate").Value = 3.625
rs.SaveRow

Method descriptions

DatabaseColumn.PictureValue

PictureValue(format As Picture.Formats, quality As Integer = Picture.QualityDefault, Assigns value As Picture)

Sets the Picture value for the column. You can get the picture value using the property of the same name.

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

rs.EditRow
rs.Column("MyIntegerColumn").Value = Nil ' sets to NULL in the database
rs.SaveRow

Get the picture value of a column in a RowSet:

' rs is a RowSet with an picture column called "Photo"
Var photo As Picture
photo = rs.Column("Photo").PictureValue

Set the picture value of a column in a RowSet:

' rs is a RowSet with an picture column called "Photo" and MyPhoto is a picture:
rs.EditRow
rs.Column("Photo").PictureValue(Picture.Formats.PNG) = MyPhoto
rs.SaveRow

Notes

Assignments to the DateTimeValue property store the time as well as the date. When getting a value, the resulting DateTime 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, DateTimeValue, 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.Column("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.EditRow
rs.Column("MyColumn").Value = Nil ' sets to NULL in the database
rs.SaveRow

Sample code

The following method populates a DesktopListBox with a RowSet. It uses the Name and StringValue properties to obtain the column names and values:

Sub PopulateListBox(dataList As DesktopListBox, rows As RowSet)
  If rows Is Nil Then Return

    ' set up listbox state for population
    dataList.RemoveAllRows

    ' Add the DB columns as the heades for the ListBox
    dataList.ColumnCount = rows.ColumnCount
    dataList.Column(-1).WidthExpression = "100"
    For i As Integer = 0 To rows.LastColumnIndex
      dataList.Heading(i) = rows.ColumnAt(i).Name
    Next

    ' Add the data from the table
   For Each row As DatabaseRow In rows
      dataList.AddRow("")

      For i As Integer = 0 To rows.LastColumnIndex
        dataList.CellTextAt(dataList.LastAddedRowIndex, i) = row.ColumnAt(i).StringValue
      Next

    Next
End Sub

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

Var myDB As SQLiteDatabase
Var rows As RowSet
rows = myDB.SelectSQL("SELECT * FROM MyTable")
Try
 rows.EditRow
 rows.Column("MyName").Value = Nil ' NULL this field, does not work for all database plugins
 rows.Column("MyID").Value = 23
 rows.Column("MyText").Value = "Test"
 rows.SaveRow
 myDB.CommitTransaction
Catch error As DatabaseException
  MessageBox("Error: " + error.Message)
End Try

Compatibility

All project types on all supported operating systems.

DatabaseColumn

Description

Properties

Methods

Property descriptions

Method descriptions

Notes

Null columns

Sample code

Compatibility

See also