--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Lib/Schema/DB/Constraint.pm	Tue Jul 14 12:54:37 2009 +0400
@@ -0,0 +1,48 @@
+package Schema::DB::Constraint;
+use Common;
+our @ISA = qw(Object);
+
+BEGIN {
+    DeclareProperty Name => ACCESS_READ;
+    DeclareProperty Table => ACCESS_READ;
+    DeclareProperty Columns => ACCESS_READ;
+}
+
+sub CTOR {
+    my ($this,%args) = @_;
+    die new Exception("The table argument must be an instance of a table object") if not UNIVERSAL::isa($args{'Table'},'Schema::DB::Table');
+    $this->{$Name} = $args{'Name'};
+    $this->{$Table} = $args{'Table'};
+    $this->{$Columns} = [map { ResolveColumn($this->Table,$_) } @{$args{'Columns'}}];
+}
+
+sub ResolveColumn {
+    my ($Table,$Column) = @_;
+    
+    my $cn = UNIVERSAL::isa($Column,'Schema::DB::Column') ? $Column->Name : $Column;
+    
+    my $resolved = $Table->Column($cn);
+    die new Exception("The column is not found in the table", $cn, $Table->Name) if not $resolved;
+    return $resolved;
+}
+
+sub HasColumn {
+    my ($this,@Columns) = @_;
+    
+    my %Columns = map { $_, 1} @Columns;
+    
+    return scalar(grep { $Columns{$_->Name} } $this->Columns) == scalar(@Columns);
+}
+
+sub UniqName {
+    my ($this) = @_;
+    return $this->{$Table}->Name.'_'.$this->{$Name};
+}
+
+sub Dispose {
+    my ($this) = @_;
+    
+    delete @$this{$Table,$Columns};
+    $this->SUPER::Dispose;
+}
+1;
\ No newline at end of file