diff --git a/src/Migrator.Providers/Impl/Mysql/MySqlTransformationProvider.cs b/src/Migrator.Providers/Impl/Mysql/MySqlTransformationProvider.cs
index df68c18c..3990cefa 100644
--- a/src/Migrator.Providers/Impl/Mysql/MySqlTransformationProvider.cs
+++ b/src/Migrator.Providers/Impl/Mysql/MySqlTransformationProvider.cs
@@ -53,7 +53,14 @@ INNER JOIN information_schema.TABLE_CONSTRAINTS i
                 if (tuple.Item3 == "FOREIGN KEY")
                     RemoveForeignKey(tuple.Item1, tuple.Item2);
                 else if (tuple.Item3 == "PRIMARY KEY")
-                    ExecuteNonQuery(String.Format("ALTER TABLE {0} DROP PRIMARY KEY", table));
+                {
+                    try
+                    {
+                        ExecuteNonQuery(String.Format("ALTER TABLE {0} DROP PRIMARY KEY", table));
+                    }
+                    catch (Exception)
+                    { }
+                }
                 else if (tuple.Item3 == "UNIQUE")
                     RemoveIndex(tuple.Item1, tuple.Item2);
             }
diff --git a/src/Migrator.Providers/Impl/Oracle/OracleTransformationProvider.cs b/src/Migrator.Providers/Impl/Oracle/OracleTransformationProvider.cs
index f9c8d502..c38cee00 100644
--- a/src/Migrator.Providers/Impl/Oracle/OracleTransformationProvider.cs
+++ b/src/Migrator.Providers/Impl/Oracle/OracleTransformationProvider.cs
@@ -175,7 +175,53 @@ public override void AddColumn(string table, string sqlColumn)
 			table = QuoteTableNameIfRequired(table);
 			sqlColumn = QuoteColumnNameIfRequired(sqlColumn);
 			ExecuteNonQuery(String.Format("ALTER TABLE {0} ADD {1}", table, sqlColumn));
-		}
+		}
+
+        public override string[] GetConstraints(string table)
+        {
+            var constraints = new List<string>();
+            //using (
+            //    IDataReader reader =
+            //        ExecuteQuery(
+            //            String.Format("SELECT CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE LOWER(TABLE_NAME) = LOWER('{0}')", table)))
+            //{
+            //    while (reader.Read())
+            //    {
+            //        constraints.Add(reader.GetString(0));
+            //    }
+            //}
+
+            using (
+                IDataReader reader =
+                    ExecuteQuery(
+                        String.Format("SELECT constraint_name FROM user_constraints WHERE lower(table_name) = '{0}'", table.ToLower())))
+            {
+                while (reader.Read())
+                {
+                    constraints.Add(reader.GetString(0));
+                }
+            }
+
+            return constraints.ToArray();
+        }
+
+        protected override string GetPrimaryKeyConstraintName(string table)
+        {
+            var constraints = new List<string>();
+
+            using (
+                IDataReader reader =
+                    ExecuteQuery(
+                        String.Format("SELECT constraint_name FROM user_constraints WHERE lower(table_name) = '{0}' and constraint_type = 'P'", table.ToLower())))
+            {
+                while (reader.Read())
+                {
+                    constraints.Add(reader.GetString(0));
+                }
+            }
+
+            return constraints.FirstOrDefault();
+        }
 
 		public override bool ConstraintExists(string table, string name)
 		{
@@ -207,7 +253,7 @@ public override bool TableExists(string table)
             string sql = string.Format("SELECT COUNT(table_name) FROM user_tables WHERE lower(table_name) = '{0}'", table.ToLower());
 
             if (_defaultSchema != null)
-                sql = string.Format("SELECT COUNT(table_name) FROM all_tables WHERE lower(owner) = '{0}' and lower(table_name) = '{1}'", _defaultSchema.ToLower(), table.ToLower());
+                sql = string.Format("SELECT COUNT(table_name) FROM user_tables WHERE lower(owner) = '{0}' and lower(table_name) = '{1}'", _defaultSchema.ToLower(), table.ToLower());
 
             Logger.Log(sql);
             object count = ExecuteScalar(sql);
@@ -472,19 +518,19 @@ private string SchemaInfoTableName
             }
         }
 
-        protected override string GetPrimaryKeyConstraintName(string table)
-        {
-            var sql = "select constraint_name " +
-                        "from user_indexes join user_constraints on user_indexes.index_name = user_constraints.constraint_name " +
-                        "where lower(user_indexes.table_name) = lower('{0}') and constraint_type = 'P'";
+        //protected override string GetPrimaryKeyConstraintName(string table)
+        //{
+        //    var sql = "select constraint_name " +
+        //                "from user_indexes join user_constraints on user_indexes.index_name = user_constraints.constraint_name " +
+        //                "where lower(user_indexes.table_name) = lower('{0}') and constraint_type = 'P'";
 
-            sql = string.Format(sql, table);
+        //    sql = string.Format(sql, table);
 
-            using (IDataReader reader = ExecuteQuery(sql))
-            {
-                return reader.Read() ? reader.GetString(0) : null;
-            }
-        }
+        //    using (IDataReader reader = ExecuteQuery(sql))
+        //    {
+        //        return reader.Read() ? reader.GetString(0) : null;
+        //    }
+        //}
         
 	    public override Index[] GetIndexes(string table)
         {
diff --git a/src/Migrator.Providers/TransformationProvider.cs b/src/Migrator.Providers/TransformationProvider.cs
index 57da3609..3e17091b 100644
--- a/src/Migrator.Providers/TransformationProvider.cs
+++ b/src/Migrator.Providers/TransformationProvider.cs
@@ -1539,7 +1539,7 @@ protected string QuoteConstraintNameIfRequired(string name)
 
         protected virtual string GetPrimaryKeyConstraintName(string table)
         {
-            throw new NotImplementedException();
+            return null;
         }
 
         public virtual void RemovePrimaryKey(string table)