Add support for concatenating expressions. Closes #51.

DatabaseObjects.vbproj

@@ -192,6 +192,7 @@
     <Compile Include="Misc\AssemblyInfo.vb" />
     <Compile Include="SQL\Amend\SQLInsertFromSelect.vb" />
     <Compile Include="SQL\Amend\SQLUpdateField.vb" />
+    <Compile Include="SQL\Expressions\SQLStringConcatExpression.vb" />
     <Compile Include="SQL\Expressions\SQLAggregateExpression.vb" />
     <Compile Include="SQL\Expressions\SQLAllFieldsExpression.vb" />
     <Compile Include="SQL\Expressions\SQLRightFunctionExpression.vb" />

SQL/Expressions/SQLStringConcatExpression.vb

@@ -0,0 +1,116 @@
+' ___________________________________________________
+'
+'  © Hi-Integrity Systems 2012. All rights reserved.
+'  www.hisystems.com.au - Toby Wicks
+' ___________________________________________________
+'
+
+Option Strict On
+Option Explicit On
+Option Infer On
+
+Imports System.Linq
+
+Namespace SQL
+
+    Public Class SQLStringConcatExpression
+        Inherits SQLExpression
+
+        Private _left As SQLExpression
+        Private _right As SQLExpression
+
+        Public Sub New()
+
+
+        End Sub
+
+        Public Sub New(ByVal leftString As String, ByVal rightString As String)
+
+            Me.New(New SQLValueExpression(leftString), New SQLValueExpression(rightString))
+
+        End Sub
+
+        Public Sub New(ByVal leftExpression As SQLExpression, ByVal rightExpression As SQLExpression)
+
+            Me.LeftExpression = leftExpression
+            Me.RightExpression = rightExpression
+
+        End Sub
+
+        Public Property LeftExpression() As SQLExpression
+            Get
+
+                Return _left
+
+            End Get
+
+            Set(ByVal value As SQLExpression)
+
+                If value Is Nothing Then
+                    Throw New ArgumentNullException
+                End If
+
+                _left = value
+
+            End Set
+        End Property
+
+        Public Property RightExpression() As SQLExpression
+            Get
+
+                Return _right
+
+            End Get
+
+            Set(ByVal value As SQLExpression)
+
+                If value Is Nothing Then
+                    Throw New ArgumentNullException
+                End If
+
+                _right = value
+
+            End Set
+        End Property
+
+        Friend Overrides Function SQL(ByVal eConnectionType As Database.ConnectionType) As String
+
+            If _left Is Nothing Then
+                Throw New ArgumentNullException(Me.GetType.Name & ".LeftExpression")
+            ElseIf _right Is Nothing Then
+                Throw New ArgumentNullException(Me.GetType.Name & ".RightExpression")
+            End If
+
+            Return _left.SQL(eConnectionType) & " + " & _right.SQL(eConnectionType)
+
+        End Function
+
+        Public Shared Function ConcatenateAll(ParamArray sqlExpressions() As SQLExpression) As SQLExpression
+
+            If sqlExpressions.Length < 2 Then
+                Throw New ArgumentException("Two or more expressions are required for string concatenation")
+            End If
+
+            Dim currentExpression As SQLStringConcatExpression = Nothing
+
+            currentExpression = New SQLStringConcatExpression()
+            currentExpression.LeftExpression = sqlExpressions(0)
+            currentExpression.RightExpression = sqlExpressions(1)
+
+            For Each sqlExpression In sqlExpressions.Skip(2)
+
+                Dim newExpression As New SQLStringConcatExpression()
+                newExpression.LeftExpression = currentExpression
+                newExpression.RightExpression = sqlExpression
+
+                currentExpression = newExpression
+            Next
+
+            Return currentExpression
+
+        End Function
+
+    End Class
+
+End Namespace
+