Table creation implemented

lib/models/table_column_definition.dart

@@ -0,0 +1,88 @@
+abstract class TableColumnDefinition {
+  final String columnName;
+  final bool isUnique;
+
+  TableColumnDefinition({
+    required this.columnName,
+    required this.isUnique,
+  });
+
+  String get def => throw UnimplementedError("def getter not implemented");
+}
+
+class SerialPrimaryColumnDefinition extends TableColumnDefinition {
+  SerialPrimaryColumnDefinition({
+    required super.columnName,
+  }) : super(isUnique: true);
+
+  @override
+  String get def => "$columnName:serial:primary";
+}
+
+class TextColumnDefinition extends TableColumnDefinition {
+  TextColumnDefinition({
+    required super.columnName,
+    required super.isUnique,
+  });
+
+  @override
+  String get def => "$columnName:str${isUnique ? ":unique" : ""}";
+}
+
+class BooleanColumnDefinition extends TableColumnDefinition {
+  BooleanColumnDefinition({
+    required super.columnName,
+    required super.isUnique,
+  });
+
+  @override
+  String get def => "$columnName:bool${isUnique ? ":unique" : ""}";
+}
+
+class TimestampColumnDefinition extends TableColumnDefinition {
+  TimestampColumnDefinition({
+    required super.columnName,
+    required super.isUnique,
+  });
+
+  @override
+  String get def => "$columnName:datetime${isUnique ? ":unique" : ""}";
+}
+
+class DoubleColumnDefinition extends TableColumnDefinition {
+  DoubleColumnDefinition({
+    required super.columnName,
+    required super.isUnique,
+  });
+
+  @override
+  String get def => "$columnName:float${isUnique ? ":unique" : ""}";
+}
+
+class IntegerColumnDefinition extends TableColumnDefinition {
+  IntegerColumnDefinition({
+    required super.columnName,
+    required super.isUnique,
+  });
+
+  @override
+  String get def => "$columnName:int${isUnique ? ":unique" : ""}";
+}
+
+class UserRefColumnDefinition extends TableColumnDefinition {
+  UserRefColumnDefinition({
+    required super.columnName,
+  }) : super(isUnique: false);
+
+  @override
+  String get def => "$columnName:int-user";
+}
+
+class AssetRefColumnDefinition extends TableColumnDefinition {
+  AssetRefColumnDefinition({
+    required super.columnName,
+  }) : super(isUnique: false);
+
+  @override
+  String get def => "$columnName:int-asset";
+}