--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Source/Data/Sql/SqlField.cs	Thu Mar 27 21:46:09 2014 +0400
@@ -0,0 +1,148 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace BLToolkit.Data.Sql
+{
+	using DataAccess;
+	using Mapping;
+
+	public class SqlField : IChild<ISqlTableSource>, ISqlExpression
+	{
+		public SqlField()
+		{
+		}
+
+		public SqlField(SqlField field)
+			: this(field.SystemType, field.Name, field.PhysicalName, field.Nullable, field.PrimaryKeyOrder, field._nonUpdatableAttribute, field.MemberMapper)
+		{
+		}
+
+		public SqlField(
+			Type                  systemType,
+			string                name,
+			string                physicalName,
+			bool                  nullable,
+			int                   pkOrder,
+			NonUpdatableAttribute nonUpdatableAttribute,
+			MemberMapper          memberMapper)
+		{
+			SystemType             = systemType;
+			Alias                  = name.Replace('.', '_');
+			Name                   = name;
+			Nullable               = nullable;
+			PrimaryKeyOrder        = pkOrder;
+			_memberMapper          = memberMapper;
+			_physicalName          = physicalName;
+			_nonUpdatableAttribute = nonUpdatableAttribute;
+		}
+
+		public Type            SystemType      { get; set; }
+		public string          Alias           { get; set; }
+		public string          Name            { get; set; }
+		public bool            Nullable        { get; set; }
+		public int             PrimaryKeyOrder { get; set; }
+		public ISqlTableSource Table           { get; private set; }
+
+		readonly MemberMapper _memberMapper;
+		public   MemberMapper  MemberMapper
+		{
+			get { return _memberMapper; }
+		}
+
+		private string _physicalName;
+		public  string  PhysicalName
+		{
+			get { return _physicalName ?? Name; }
+			set { _physicalName = value; }
+		}
+
+		public bool IsIdentity   { get { return _nonUpdatableAttribute != null && _nonUpdatableAttribute.IsIdentity; } }
+		public bool IsInsertable { get { return _nonUpdatableAttribute == null || !_nonUpdatableAttribute.OnInsert;  } }
+		public bool IsUpdatable  { get { return _nonUpdatableAttribute == null || !_nonUpdatableAttribute.OnUpdate;  } }
+
+		public bool IsPrimaryKey { get { return PrimaryKeyOrder != int.MinValue; } }
+
+		readonly NonUpdatableAttribute  _nonUpdatableAttribute;
+
+		ISqlTableSource IChild<ISqlTableSource>.Parent { get { return Table; } set { Table = value; } }
+
+		#region Overrides
+
+#if OVERRIDETOSTRING
+
+		public override string ToString()
+		{
+			return ((IQueryElement)this).ToString(new StringBuilder(), new Dictionary<IQueryElement,IQueryElement>()).ToString();
+		}
+
+#endif
+
+		#endregion
+
+		#region ISqlExpression Members
+
+		public bool CanBeNull()
+		{
+			return Nullable;
+		}
+
+		public bool Equals(ISqlExpression other, Func<ISqlExpression,ISqlExpression,bool> comparer)
+		{
+			return this == other;
+		}
+
+		public int Precedence
+		{
+			get { return Sql.Precedence.Primary; }
+		}
+
+		#endregion
+
+		#region ISqlExpressionWalkable Members
+
+		ISqlExpression ISqlExpressionWalkable.Walk(bool skipColumns, Func<ISqlExpression,ISqlExpression> func)
+		{
+			return func(this);
+		}
+
+		#endregion
+
+		#region IEquatable<ISqlExpression> Members
+
+		bool IEquatable<ISqlExpression>.Equals(ISqlExpression other)
+		{
+			return this == other;
+		}
+
+		#endregion
+
+		#region ICloneableElement Members
+
+		public ICloneableElement Clone(Dictionary<ICloneableElement, ICloneableElement> objectTree, Predicate<ICloneableElement> doClone)
+		{
+			if (!doClone(this))
+				return this;
+
+			Table.Clone(objectTree, doClone);
+			return objectTree[this];
+		}
+
+		#endregion
+
+		#region IQueryElement Members
+
+		public QueryElementType ElementType { get { return QueryElementType.SqlField; } }
+
+		StringBuilder IQueryElement.ToString(StringBuilder sb, Dictionary<IQueryElement,IQueryElement> dic)
+		{
+			return sb
+				.Append('t')
+				.Append(Table.SourceID)
+				.Append('.')
+				.Append(Name);
+		}
+
+		#endregion
+	}
+}