diff --git a/src/deveeldb-nunit/Deveel.Data/ShowTests.cs b/src/deveeldb-nunit/Deveel.Data/ShowTests.cs
index a33a1475..d00d92a6 100644
--- a/src/deveeldb-nunit/Deveel.Data/ShowTests.cs
+++ b/src/deveeldb-nunit/Deveel.Data/ShowTests.cs
@@ -14,19 +14,76 @@
 //    limitations under the License.
 
 using System;
+using System.Linq;
+
+using Deveel.Data.Security;
+using Deveel.Data.Sql;
+using Deveel.Data.Sql.Cursors;
+using Deveel.Data.Sql.Tables;
+using Deveel.Data.Sql.Types;
 
 using NUnit.Framework;
 
 namespace Deveel.Data {
 	[TestFixture]
 	public sealed class ShowTests : ContextBasedTest {
+		protected override bool OnSetUp(string testName, IQuery query) {
+			var tableName = ObjectName.Parse("SYSTEM.test_table");
+			var tableInfo = new TableInfo(tableName);
+			tableInfo.AddColumn("a", PrimitiveTypes.Integer());
+			tableInfo.AddColumn("b", PrimitiveTypes.String());
+
+			query.Access().CreateObject(tableInfo);
+			query.Access().GrantOnTable(tableName, User.PublicName, Privileges.TableAll);
+
+			return true;
+		}
+
+		protected override bool OnTearDown(string testName, IQuery query) {
+			var tableName = ObjectName.Parse("SYSTEM.test_table");
+			query.Access().RevokeAllGrantsOn(DbObjectType.Table, tableName);
+			query.Access().DropObject(DbObjectType.Table, tableName);
+			return true;
+		}
+
 		[Test]
 		public void ShowSchema() {
 			var result = Query.ShowSchema();
 
 			Assert.IsNotNull(result);
 
-			// TODO: Verify the list of schema is coherent
+			Row row = null;
+			Assert.DoesNotThrow(() => row = result.ElementAt(0));
+			Assert.IsNotNull(row);
+
+			var schemaName = row.GetValue(0).Value.ToString();
+			var schemaType = row.GetValue(1).Value.ToString();
+
+			Assert.AreEqual("INFORMATION_SCHEMA", schemaName);
+			Assert.AreEqual("SYSTEM", schemaType);
+		}
+
+		[Test]
+		public void ShowTables() {
+			var result = Query.ShowTables();
+
+			Assert.IsNotNull(result);
+
+			// TODO: There's probably an error on the views to select
+			//        the tables the current user has access to... so for the moment
+			//        just be happy it doesn't throw an error: we will come back later
+		}
+
+		[Test]
+		public void ShowProduct() {
+			var result = Query.ShowProduct();
+
+			Assert.IsNotNull(result);
+
+			// TODO: the product information come from the variables table,
+			//        that is not yet finalized: so the execution succeeds but
+			//        no data are retrieved. come back later when database vars
+			//        are implemented
 		}
 	}
 }
diff --git a/src/deveeldb/Deveel.Data.Routines/InvokeArgument.cs b/src/deveeldb/Deveel.Data.Routines/InvokeArgument.cs
index e7588fe2..41f8260e 100644
--- a/src/deveeldb/Deveel.Data.Routines/InvokeArgument.cs
+++ b/src/deveeldb/Deveel.Data.Routines/InvokeArgument.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Runtime.Serialization;
+using System.Text;
 
 using Deveel.Data.Sql.Expressions;
 
@@ -40,5 +41,16 @@ public InvokeArgument(SqlExpression value)
 			var preparedValue = Value.Prepare(preparer);
 			return new InvokeArgument(Name, preparedValue);
 		}
+
+		public override string ToString() {
+			var sb = new StringBuilder();
+			if (IsNamed) {
+				sb.AppendFormat("{0} => ", Name);
+			}
+
+			sb.Append(Value);
+
+			return sb.ToString();
+		}
 	}
 }
diff --git a/src/deveeldb/Deveel.Data.Routines/SystemFunctions.cs b/src/deveeldb/Deveel.Data.Routines/SystemFunctions.cs
index f36970d9..e6e5375d 100644
--- a/src/deveeldb/Deveel.Data.Routines/SystemFunctions.cs
+++ b/src/deveeldb/Deveel.Data.Routines/SystemFunctions.cs
@@ -16,8 +16,11 @@
 
 
 using System;
+using System.Globalization;
+using System.Text;
 
 using Deveel.Data;
+using Deveel.Data.Security;
 using Deveel.Data.Sql;
 using Deveel.Data.Sql.Expressions;
 using Deveel.Data.Sql.Objects;
@@ -282,6 +285,30 @@ public static class SystemFunctions {
 
 		#endregion
 
+		public static Field Concat(Field[] args) {
+			var cc = new StringBuilder();
+
+			CultureInfo locale = null;
+			foreach (var ob in args) {
+				if (ob.IsNull)
+					return ob;
+
+				cc.Append(ob.Value);
+
+				var type1 = ob.Type;
+				if (locale == null && type1 is StringType) {
+					var strType = (StringType)type1;
+					locale = strType.Locale;
+				}
+			}
+
+			// We inherit the locale from the first string parameter with a locale,
+			// or use a default VarString if no locale found.
+			var type = locale != null ? PrimitiveTypes.VarChar(locale) : PrimitiveTypes.VarChar();
+
+			return new Field(type, new SqlString(cc.ToString()));
+		}
+
 		internal static InvokeResult Iif(InvokeContext context) {
 			var result = Field.Null();
 
@@ -343,5 +370,11 @@ public static class SystemFunctions {
 
 			throw new InvalidOperationException("Unsupported type in function argument");
 		}
+
+		internal static Field PrivilegeString(Field ob) {
+			int privBit = ((SqlNumber)ob.Value).ToInt32();
+			var privs = (Privileges)privBit;
+			return Field.String(privs.ToString());
+		}
 	}
 }
\ No newline at end of file
diff --git a/src/deveeldb/Deveel.Data.Routines/SystemFunctionsProvider.cs b/src/deveeldb/Deveel.Data.Routines/SystemFunctionsProvider.cs
index d8e9ac6e..2c2d4765 100644
--- a/src/deveeldb/Deveel.Data.Routines/SystemFunctionsProvider.cs
+++ b/src/deveeldb/Deveel.Data.Routines/SystemFunctionsProvider.cs
@@ -17,6 +17,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 
 using Deveel.Data;
 using Deveel.Data.Sql;
@@ -50,6 +51,20 @@ class SystemFunctionsProvider : FunctionProvider {
 			return exp.ReturnType(context.Request, context.VariableResolver);
 		}
 
+		private static SqlType ConcatReturnType(InvokeContext context) {
+			// Determine the locale of the first string parameter.
+			CultureInfo locale = null;
+			for (int i = 0; i < context.ArgumentCount && locale == null; ++i) {
+				var type = ReturnType(context.Arguments[i].Value, context);
+				if (type is StringType) {
+					StringType strType = (StringType)type;
+					locale = strType.Locale;
+				}
+			}
+
+			return locale != null ? PrimitiveTypes.VarChar(locale) : PrimitiveTypes.VarChar();
+		}
+
 		#endregion
 
 		#region Aggregate Functions
@@ -60,7 +75,9 @@ class SystemFunctionsProvider : FunctionProvider {
 				.Named("aggor")
 				.WithParameter(p => p.Named("args").Unbounded().OfDynamicType())
 				.OfAggregateType()
-				.WhenExecute(context => Binary(context, SystemFunctions.Or)));
+				.WhenExecute(context => {
+					return Binary(context, SystemFunctions.Or);
+				}));
 
 			// COUNT
 			Register(config => config.Named("count")
@@ -451,6 +468,11 @@ class DistinctComparer : IComparer<int> {
 					return argType is StringType ? (SqlType) PrimitiveTypes.Numeric() : (SqlType) PrimitiveTypes.String();
 				}));
 
+			Register(config => config.Named("i_privilege_string")
+				.WithNumericParameter("privBit")
+				.WhenExecute(context => Simple(context, args => SystemFunctions.PrivilegeString(args[0])))
+				.ReturnsString());
+
 			// VERSION
 			Register(config => config
 			.Named("version")
@@ -544,6 +566,18 @@ class DistinctComparer : IComparer<int> {
 
 		#endregion
 
+		#region String Functions
+
+		private void StringFunctions() {
+			// CONCAT([STRING])
+			Register(config => config.Named("concat")
+				.WithUnoundedParameter("strings", PrimitiveTypes.VarChar())
+				.WhenExecute(context => Simple(context, args => SystemFunctions.Concat(args)))
+				.ReturnsType(ConcatReturnType));
+		}
+
+		#endregion
+
 		protected override void OnInit() {
 			AggregateFunctions();
 
@@ -551,6 +585,7 @@ class DistinctComparer : IComparer<int> {
 			SecurityFunctions();
 			SequenceFunctions();
 			DateFunctions();
+			StringFunctions();
 
 			MiscFunctions();
 		}
diff --git a/src/deveeldb/Deveel.Data.Sql.Cursors/NativeCursor.cs b/src/deveeldb/Deveel.Data.Sql.Cursors/NativeCursor.cs
index 1190a72e..6cc49b44 100644
--- a/src/deveeldb/Deveel.Data.Sql.Cursors/NativeCursor.cs
+++ b/src/deveeldb/Deveel.Data.Sql.Cursors/NativeCursor.cs
@@ -129,6 +129,9 @@ class NativeCursor : ICursor {
 		public CursorStatus Status { get; private set; }
 
 		public Row Fetch(FetchDirection direction, int offset) {
+			if (Result == null)
+				return null;
+
 			if (direction != FetchDirection.Absolute &&
 				direction != FetchDirection.Relative &&
 				offset > -1)
diff --git a/src/deveeldb/Deveel.Data.Sql.Expressions/PreparerVisitor.cs b/src/deveeldb/Deveel.Data.Sql.Expressions/PreparerVisitor.cs
index 92c062c0..08a04248 100644
--- a/src/deveeldb/Deveel.Data.Sql.Expressions/PreparerVisitor.cs
+++ b/src/deveeldb/Deveel.Data.Sql.Expressions/PreparerVisitor.cs
@@ -87,7 +87,22 @@ private static IEnumerable<T> Prepare<T>(IEnumerable<T> list, IExpressionPrepare
 			if (nextComposite != null)
 				nextComposite = (SqlQueryExpression) nextComposite.Prepare(preparer);
 
+			var groupBy = query.GroupBy;
+			if (groupBy != null) {
+				var newGroupBy = new List<SqlExpression>();
+				foreach (var groupExpression in groupBy) {
+					var newGroupByExp = groupExpression.Prepare(preparer);
+					newGroupBy.Add(newGroupByExp);
+				}
+
+				newExpression.GroupBy = newGroupBy;
+			}
+
 			newExpression.NextComposite = nextComposite;
+			newExpression.CompositeFunction = query.CompositeFunction;
+			newExpression.IsCompositeAll = query.IsCompositeAll;
+
+			newExpression.Distinct = query.Distinct;
 
 			return newExpression;
 		}
diff --git a/src/deveeldb/Deveel.Data.Sql.Query/SubsetNode.cs b/src/deveeldb/Deveel.Data.Sql.Query/SubsetNode.cs
index 000d04c1..2731978c 100644
--- a/src/deveeldb/Deveel.Data.Sql.Query/SubsetNode.cs
+++ b/src/deveeldb/Deveel.Data.Sql.Query/SubsetNode.cs
@@ -46,12 +46,14 @@ private SubsetNode(SerializationInfo info, StreamingContext context)
 		}
 
 		public void SetAliasParentName(ObjectName parentName) {
-			var aliases = new ObjectName[AliasColumnNames.Length];
-			for (int i = 0; i < aliases.Length; i++) {
-				aliases[i] = new ObjectName(parentName, AliasColumnNames[i].Name);
-			}
+			if (parentName != null) {
+				var aliases = new ObjectName[AliasColumnNames.Length];
+				for (int i = 0; i < aliases.Length; i++) {
+					aliases[i] = new ObjectName(parentName, AliasColumnNames[i].Name);
+				}
 
-			AliasColumnNames = aliases;
+				AliasColumnNames = aliases;
+			}
 		}
 
 		protected override void GetData(SerializationInfo info, StreamingContext context) {
diff --git a/src/deveeldb/Deveel.Data.Sql.Schemas/InfortmationSchemaCreate.cs b/src/deveeldb/Deveel.Data.Sql.Schemas/InfortmationSchemaCreate.cs
index 4b6294ec..831fdca9 100644
--- a/src/deveeldb/Deveel.Data.Sql.Schemas/InfortmationSchemaCreate.cs
+++ b/src/deveeldb/Deveel.Data.Sql.Schemas/InfortmationSchemaCreate.cs
@@ -28,14 +28,14 @@ class InfortmationSchemaCreate : IDatabaseCreateCallback {
 			                   "  SELECT \"priv_bit\", \"object\", \"name\", \"grantee\", " +
 			                   "         \"grant_option\", \"granter\" " +
 			                   "    FROM " + SystemSchema.GrantsTableName +
-			                   "   WHERE ( grantee = user() OR grantee = '@PUBLIC' )");
+			                   "   WHERE ( grantee = user() OR grantee = '" + User.PublicName + "' )");
 
 			// This view shows the grants that the user is allowed to see
 			query.ExecuteQuery("CREATE VIEW " + InformationSchema.ThisUserGrantViewName + " AS " +
 			                   "  SELECT \"description\", \"object\", \"name\", \"grantee\", " +
 			                   "         \"grant_option\", \"granter\" " +
 			                   "    FROM " + SystemSchema.GrantsTableName + ", " + SystemSchema.PrivilegesTableName +
-			                   "   WHERE ( grantee = user() OR grantee = '@PUBLIC' )" +
+			                   "   WHERE ( grantee = user() OR grantee = '" + User.PublicName + "' )" +
 			                   "     AND " + SystemSchema.GrantsTableName + ".priv_bit = " +
 			                   SystemSchema.PrivilegesTableName + ".priv_bit");
 
@@ -112,9 +112,9 @@ class InfortmationSchemaCreate : IDatabaseCreateCallback {
 			                   "         \"TABLE_SCHEMA\",\n" +
 			                   "         \"TABLE_NAME\",\n" +
 			                   "         \"COLUMN_NAME\",\n" +
-			                   "         IIF(\"" + InformationSchema.ThisUserGrantViewName + ".granter\" = '@SYSTEM', \n" +
+			                   "         IIF(\"" + InformationSchema.ThisUserGrantViewName + ".granter\" = '" + User.SystemName + "', \n" +
 			                   "                        NULL, \"ThisUserGrant.granter\") AS \"GRANTOR\",\n" +
-			                   "         IIF(\"" + InformationSchema.ThisUserGrantViewName + ".grantee\" = '@PUBLIC', \n" +
+			                   "         IIF(\"" + InformationSchema.ThisUserGrantViewName + ".grantee\" = '" + User.PublicName +"', \n" +
 			                   "                    'public', \"ThisUserGrant.grantee\") AS \"GRANTEE\",\n" +
 			                   "         \"" + InformationSchema.ThisUserGrantViewName + ".description\" AS \"PRIVILEGE\",\n" +
 			                   "         IIF(\"grant_option\" = 'true', 'YES', 'NO') AS \"IS_GRANTABLE\" \n" +
@@ -128,9 +128,9 @@ class InfortmationSchemaCreate : IDatabaseCreateCallback {
 			                   "  SELECT \"TABLE_CATALOG\",\n" +
 			                   "         \"TABLE_SCHEMA\",\n" +
 			                   "         \"TABLE_NAME\",\n" +
-			                   "         IIF(\"" + InformationSchema.ThisUserGrantViewName + ".granter\" = '@SYSTEM', \n" +
+			                   "         IIF(\"" + InformationSchema.ThisUserGrantViewName + ".granter\" = '" + User.SystemName + "', \n" +
 			                   "                        NULL, \"ThisUserGrant.granter\") AS \"GRANTOR\",\n" +
-			                   "         IIF(\"" + InformationSchema.ThisUserGrantViewName + ".grantee\" = '@PUBLIC', \n" +
+			                   "         IIF(\"" + InformationSchema.ThisUserGrantViewName + ".grantee\" = '" + User.PublicName + "', \n" +
 			                   "                    'public', \"ThisUserGrant.grantee\") AS \"GRANTEE\",\n" +
 			                   "         \"" + InformationSchema.ThisUserGrantViewName + ".description\" AS \"PRIVILEGE\",\n" +
 			                   "         IIF(\"grant_option\" = 'true', 'YES', 'NO') AS \"IS_GRANTABLE\" \n" +
diff --git a/src/deveeldb/Deveel.Data.Sql.Statements/SelectStatement.cs b/src/deveeldb/Deveel.Data.Sql.Statements/SelectStatement.cs
index 2ebdf784..2c12b58d 100644
--- a/src/deveeldb/Deveel.Data.Sql.Statements/SelectStatement.cs
+++ b/src/deveeldb/Deveel.Data.Sql.Statements/SelectStatement.cs
@@ -78,6 +78,24 @@ private SelectStatement(SerializationInfo info, StreamingContext context)
 			}
 		}
 
+		protected override SqlStatement PrepareExpressions(IExpressionPreparer preparer) {
+			var preparedQuery = QueryExpression.Prepare(preparer);
+			if (!(preparedQuery is SqlQueryExpression))
+				throw new StatementException("The preparation of the query expression resulted in an invalid expression.");
+
+			var orderBy = new List<SortColumn>();
+			if (OrderBy != null) {
+				foreach (var column in OrderBy) {
+					var prepared = (SortColumn) ((IPreparable) column).Prepare(preparer);
+					orderBy.Add(prepared);
+				}
+			}
+
+			var query = (SqlQueryExpression) preparedQuery;
+
+			return new SelectStatement(query, Limit, orderBy);
+		}
+
 		protected override SqlStatement PrepareStatement(IRequest context) {
 			var queryPlan = context.Query.Context.QueryPlanner().PlanQuery(new QueryInfo(context, QueryExpression, OrderBy, Limit));
 			return new Prepared(queryPlan);
diff --git a/src/deveeldb/Deveel.Data.Sql.Statements/ShowStatement.cs b/src/deveeldb/Deveel.Data.Sql.Statements/ShowStatement.cs
index f6a1f3c1..282c2ead 100644
--- a/src/deveeldb/Deveel.Data.Sql.Statements/ShowStatement.cs
+++ b/src/deveeldb/Deveel.Data.Sql.Statements/ShowStatement.cs
@@ -16,10 +16,13 @@
 
 
 using System;
+using System.Runtime.Serialization;
 
 using Deveel.Data.Sql.Expressions;
+using Deveel.Data.Sql.Objects;
 using Deveel.Data.Sql.Schemas;
 using Deveel.Data.Sql.Tables;
+using Deveel.Data.Sql.Types;
 
 namespace Deveel.Data.Sql.Statements {
 	[Serializable]
@@ -47,57 +50,118 @@ public ShowStatement(ShowTarget target)
 			}
 
 			if (Target == ShowTarget.Schema)
-				return ShowSchema(context.Context);
+				return ShowSchema();
 			if (Target == ShowTarget.SchemaTables)
-				return ShowSchemaTables(context.Query.CurrentSchema(), context.Context);
+				return ShowSchemaTables(context.Query.CurrentSchema());
+			if (Target == ShowTarget.Table)
+				return ShowTable(tableName);
+			if (Target == ShowTarget.Product)
+				return ShowProduct();
 
 			throw new StatementException(String.Format("The SHOW target {0} is not supported.", Target));
 		}
 
-		private static SqlStatement Show(IContext context, string sql, params SortColumn[] orderBy) {
-			var query = (SqlQueryExpression)SqlExpression.Parse(sql, context);
-			var select = new SelectStatement(query, orderBy);
-			return new Prepared(select);
+		private static SqlStatement Show(string sql, params QueryParameter[] parameters) {
+			var query = new SqlQuery(sql);
+			if (parameters != null && parameters.Length > 0) {
+				foreach (var parameter in parameters) {
+					query.Parameters.Add(parameter);
+				}
+			}
+
+			return new Prepared(query);
 		}
 
-		private SqlStatement ShowSchema(IContext systemContext) {
+		private SqlStatement ShowSchema() {
 			var sql = "SELECT \"name\" AS \"schema_name\", " +
 			          "       \"type\", " +
 			          "       \"other\" AS \"notes\" " +
-			          "    FROM " + InformationSchema.ThisUserSchemaInfoViewName;
+			          "    FROM " + InformationSchema.ThisUserSchemaInfoViewName + " " +
+					  "ORDER BY \"schema_name\"";
 
-			return Show(systemContext, sql, new SortColumn("schema_name"));
+			return Show(sql);
 		}
 
-		private SqlStatement ShowSchemaTables(string schema, IContext context) {
+		private SqlStatement ShowProduct() {
+			const string sql = "SELECT \"name\", \"version\" FROM " +
+			                   "  ( SELECT \"value\" AS \"name\" FROM SYSTEM.product_info " +
+			                   "     WHERE \"var\" = 'name' ), " +
+			                   "  ( SELECT \"value\" AS \"version\" FROM SYSTEM.product_info " +
+			                   "     WHERE \"var\" = 'version' ) ";
+
+			return Show(sql);
+		}
+
+		private SqlStatement ShowSchemaTables(string schema) {
 			var sql = "  SELECT \"Tables.TABLE_NAME\" AS \"table_name\", " +
 			          "         I_PRIVILEGE_STRING(\"agg_priv_bit\") AS \"user_privs\", " +
 			          "         \"Tables.TABLE_TYPE\" as \"table_type\" " +
 			          "    FROM " + InformationSchema.Tables + ", " +
 			          "         ( SELECT AGGOR(\"priv_bit\") agg_priv_bit, " +
-			          "                  \"object\", \"param\" " +
+			          "                  \"object\", \"name\" " +
 			          "             FROM " + InformationSchema.ThisUserSimpleGrantViewName +
-			          "            WHERE \"object\" = 1 " +
-			          "         GROUP BY \"param\" )" +
-			          "   WHERE \"Tables.TABLE_SCHEMA\" = \"" + schema + "\" " +
-			          "     AND CONCAT(\"Tables.TABLE_SCHEMA\", '.', \"Tables.TABLE_NAME\") = \"param\" ";
-			return Show(context, sql, new SortColumn("Tables.TABLE_NAME"));
+			          "            WHERE \"object\" = " + ((int)DbObjectType.Table) +
+			          "         GROUP BY \"name\" )" +
+			          "   WHERE \"Tables.TABLE_SCHEMA\" = ? " +
+			          "     AND CONCAT(\"Tables.TABLE_SCHEMA\", '.', \"Tables.TABLE_NAME\") = \"name\" " +
+					  "ORDER BY Tables.TABLE_NAME";
+
+			var param = new QueryParameter(PrimitiveTypes.String(), new SqlString(schema));
+			return Show(sql, param);
+		}
+
+		private SqlStatement ShowTable(ObjectName tableName) {
+			var sql = "  SELECT \"column\" AS \"name\", " +
+			          "         i_sql_type(\"type_desc\", \"size\", \"scale\") AS \"type\", " +
+			          "         \"not_null\", " +
+			          "         \"index_str\" AS \"index\", " +
+			          "         \"default\" " +
+			          "    FROM " + InformationSchema.ThisUserTableColumnsViewName + " " +
+			          "   WHERE \"schema\" = ? " +
+			          "     AND \"table\" = ? " +
+			          "ORDER BY \"seq_no\" ";
+
+			var parameters = new[] {
+				new QueryParameter(PrimitiveTypes.String(), new SqlString(tableName.ParentName)),
+				new QueryParameter(PrimitiveTypes.String(), new SqlString(tableName.Name)) 
+			};
+
+			return Show(sql, parameters);
 		}
 
 		#region Prepared
 
+		[Serializable]
 		class Prepared : SqlStatement {
-			public Prepared(SelectStatement select) {
-				Select = select;
+			public Prepared(SqlQuery query) {
+				Query = query;
 			}
 
-			public SelectStatement Select { get; private set; }
+			private Prepared(SerializationInfo info, StreamingContext context)
+				: base(info, context) {
+				Query = (SqlQuery) info.GetValue("Query", typeof(SqlQuery));
+			}
+
+			public SqlQuery Query { get; private set; }
+
+			protected override void GetData(SerializationInfo info) {
+				info.AddValue("Query", Query);
+				base.GetData(info);
+			}
 
 			protected override void ExecuteStatement(ExecutionContext context) {
-				var result = context.Request.ExecuteStatement(Select);
+				var results = context.Query.ExecuteQuery(Query);
+
+				if (results.Length != 1)
+					throw new StatementException("Too many queries were executed.");
+
+				var result = results[0];
+
+				if (result.Type == StatementResultType.Exception)
+					throw result.Error;
 
 				if (result.Type != StatementResultType.CursorRef)
-					throw new StatementException();
+					throw new StatementException("Invalid result for query");
 
 				context.SetCursor(result.Cursor);
 			}
diff --git a/src/deveeldb/Deveel.Data.Sql.Tables/FilterTable.cs b/src/deveeldb/Deveel.Data.Sql.Tables/FilterTable.cs
index 6220fefe..15237737 100644
--- a/src/deveeldb/Deveel.Data.Sql.Tables/FilterTable.cs
+++ b/src/deveeldb/Deveel.Data.Sql.Tables/FilterTable.cs
@@ -74,6 +74,7 @@ class FilterTable : Table {
 
 				// Index is not cached in this table so ask the parent.
 				index = Parent.GetIndex(column, originalColumn, t);
+
 				if (table == this)
 					columnIndices[column] = index;
 
diff --git a/src/deveeldb/Deveel.Data.Sql.Tables/FunctionTable.cs b/src/deveeldb/Deveel.Data.Sql.Tables/FunctionTable.cs
index 9449787d..34b04373 100644
--- a/src/deveeldb/Deveel.Data.Sql.Tables/FunctionTable.cs
+++ b/src/deveeldb/Deveel.Data.Sql.Tables/FunctionTable.cs
@@ -124,7 +124,7 @@ public FunctionTable(ITable table, SqlExpression[] functionList, string[] column
 		public override void Lock() {
 			// We Lock the reference table.
 			// NOTE: This cause the reference table to Lock twice when we use the
-			//  'MergeWithReference' method.  While this isn't perfect behaviour, it
+			//  'MergeWith' method.  While this isn't perfect behaviour, it
 			//  means if 'MergeWithReference' isn't used, we still maintain a safe
 			//  level of locking.
 			ReferenceTable.Lock();
@@ -133,7 +133,7 @@ public FunctionTable(ITable table, SqlExpression[] functionList, string[] column
 		public override void Release() {
 			// We unlock the reference table.
 			// NOTE: This cause the reference table to unlock twice when we use the
-			//  'MergeWithReference' method.  While this isn't perfect behaviour, it
+			//  'MergeWith' method.  While this isn't perfect behaviour, it
 			//  means if 'MergeWithReference' isn't used, we still maintain a safe
 			//  level of locking.
 			ReferenceTable.Release();
@@ -271,7 +271,7 @@ public FunctionTable(ITable table, SqlExpression[] functionList, string[] column
 					rowList.Add(rowEnum.Current.RowId.RowNumber);
 				} else {
 					// MAJOR HACK: If the referencing table has no elements then we choose
-					//   an arbitary index from the reference table to merge so we have
+					//   an arbitrary index from the reference table to merge so we have
 					//   at least one element in the table.
 					//   This is to fix the 'SELECT COUNT(*) FROM empty_table' bug.
 					rowList.Add(Int32.MaxValue - 1);
diff --git a/src/deveeldb/Deveel.Data.Sql.Tables/OuterTable.cs b/src/deveeldb/Deveel.Data.Sql.Tables/OuterTable.cs
index f9f76fa8..f6b9ec41 100644
--- a/src/deveeldb/Deveel.Data.Sql.Tables/OuterTable.cs
+++ b/src/deveeldb/Deveel.Data.Sql.Tables/OuterTable.cs
@@ -21,7 +21,7 @@
 using Deveel.Data.Index;
 
 namespace Deveel.Data.Sql.Tables {
-	internal class OuterTable : VirtualTable {
+	internal class OuterTable : VirtualTable, IRootTable {
 		private readonly IList<int>[] outerRows;
 		private int outerRowCount;
 
@@ -42,6 +42,10 @@ private OuterTable(IEnumerable<ITable> tables, IList<IList<int>> rows)
 			get { return base.RowCount + outerRowCount; }
 		}
 
+		bool IRootTable.TypeEquals(IRootTable other) {
+			return this == other;
+		}
+
 		public void MergeIn(ITable outsideTable) {
 			var rawTableInfo = outsideTable.GetRawTableInfo();
 
diff --git a/src/deveeldb/Deveel.Data.Sql.Tables/VirtualTable.cs b/src/deveeldb/Deveel.Data.Sql.Tables/VirtualTable.cs
index 91248150..f849b34e 100644
--- a/src/deveeldb/Deveel.Data.Sql.Tables/VirtualTable.cs
+++ b/src/deveeldb/Deveel.Data.Sql.Tables/VirtualTable.cs
@@ -73,11 +73,20 @@ public VirtualTable(ITable table, IList<int> rows)
 		}
 
 		protected override IEnumerable<int> ResolveRowsForTable(IEnumerable<int> rows, int tableNum) {
-			var rowSet = rows.ToList();
+			var rowSet = new List<int>(rows);
 			IList<int> curRowList = rowList[tableNum];
 			for (int n = rowSet.Count - 1; n >= 0; --n) {
 				int aa = rowSet[n];
-				int bb = curRowList[aa];
+				int bb;
+
+				if (aa == Int32.MaxValue - 1) {
+					bb = 0;
+				} else if (aa < 0 || aa >= curRowList.Count) {
+					throw new InvalidOperationException("Invalid row reference");
+				} else {
+					bb = curRowList[aa];
+				}
+
 				rowSet[n] = bb;
 			}
 
diff --git a/src/deveeldb/Deveel.Data/RequestExtensions.cs b/src/deveeldb/Deveel.Data/RequestExtensions.cs
index d2c74c0d..61360cfa 100644
--- a/src/deveeldb/Deveel.Data/RequestExtensions.cs
+++ b/src/deveeldb/Deveel.Data/RequestExtensions.cs
@@ -503,6 +503,10 @@ public static class RequestExtensions {
 			return request.Show(ShowTarget.SchemaTables);
 		}
 
+		public static ICursor ShowTable(this IRequest request, ObjectName tableName) {
+			return request.Show(ShowTarget.Table, tableName);
+		}
+
 		public static ICursor ShowStatus(this IRequest request) {
 			return request.Show(ShowTarget.Status);
 		}
@@ -511,6 +515,10 @@ public static class RequestExtensions {
 			return request.Show(ShowTarget.Session);
 		}
 
+		public static ICursor ShowProduct(this IRequest request) {
+			return request.Show(ShowTarget.Product);
+		}
+
 		#endregion
 
 		#endregion