Index: trunk/nhibernate/src/NHibernate.Test/DialectTest/FirebirdDialectFixture.cs
===================================================================
--- trunk/nhibernate/src/NHibernate.Test/DialectTest/FirebirdDialectFixture.cs	(revision 0)
+++ trunk/nhibernate/src/NHibernate.Test/DialectTest/FirebirdDialectFixture.cs	(revision 0)
@@ -0,0 +1,25 @@
+using NHibernate.Dialect;
+using NHibernate.SqlCommand;
+using NUnit.Framework;
+
+namespace NHibernate.Test.DialectTest
+{
+	[TestFixture]
+	public class FirebirdDialectFixture
+	{
+		[Test]
+		public void GetLimitString()
+		{
+			FirebirdDialect d = new FirebirdDialect();
+
+			SqlString str = d.GetLimitString(new SqlString("SELECT * FROM fish"), 0, 10);
+			Assert.AreEqual("SELECT first 10 * FROM fish", str.ToString());
+
+			str = d.GetLimitString(new SqlString("SELECT * FROM fish ORDER BY name"), 5, 15);
+      Assert.AreEqual("SELECT first 15 skip 5 * FROM fish ORDER BY name", str.ToString());
+
+			str = d.GetLimitString(new SqlString("SELECT * FROM fish ORDER BY name DESC"), 7, 28);
+      Assert.AreEqual("SELECT first 28 skip 7 * FROM fish ORDER BY name DESC", str.ToString());
+		}
+	}
+}
Index: trunk/nhibernate/src/NHibernate.Test/NHibernate.Test-2.0.csproj
===================================================================
--- trunk/nhibernate/src/NHibernate.Test/NHibernate.Test-2.0.csproj	(revision 2194)
+++ trunk/nhibernate/src/NHibernate.Test/NHibernate.Test-2.0.csproj	(working copy)
@@ -75,6 +75,7 @@
     <Compile Include="CompositeId\Id.cs" />
     <Compile Include="ConnectionStringTest\NamedConnectionStringFixture.cs" />
     <Compile Include="DebugConnectionProvider.cs" />
+    <Compile Include="DialectTest\FirebirdDialectFixture.cs" />
     <Compile Include="DialectTest\DialectFixture.cs" />
     <Compile Include="DialectTest\MsSql2005DialectFixture.cs" />
     <Compile Include="DialectTest\MsSqlDialectFixture.cs" />
Index: trunk/nhibernate/src/NHibernate/Dialect/FirebirdDialect.cs
===================================================================
--- trunk/nhibernate/src/NHibernate/Dialect/FirebirdDialect.cs	(revision 2194)
+++ trunk/nhibernate/src/NHibernate/Dialect/FirebirdDialect.cs	(working copy)
@@ -150,6 +150,69 @@
 			get { return true; }
 		}
 
+    public override bool SupportsLimit
+    {
+      get { return true; }
+    }
+
+    public override bool SupportsLimitOffset
+    {
+      get { return true; }
+    }
+
+    /// <summary>
+    /// Add a <c>FIRST x [SKIP] y</c> clause to the given SQL <c>SELECT</c>
+    /// </summary>
+    /// <param name="querySqlString">A Query in the form of a SqlString.</param>
+    /// <param name="limit">Maximum number of rows to be returned by the query</param>
+    /// <param name="offset">Offset of the first row to process in the result set</param>
+    /// <returns>A new SqlString that contains the <c>FIRST</c> clause.</returns>
+    public override SqlString GetLimitString(SqlString querySqlString, int offset, int limit)
+    {
+      /*
+       * "SELECT FIRST x [SKIP y] rest-of-sql-statement"
+       */
+      querySqlString = querySqlString.Compact();
+      SqlStringBuilder pagingBuilder = new SqlStringBuilder();
+      bool firstAdded = false;
+      foreach (object sqlPart in querySqlString.SqlParts)
+      {
+        if (!firstAdded)
+        {
+          string sqlPartString = sqlPart as string;
+          if (sqlPartString != null)
+          {
+            string sqlFragment = sqlPartString.TrimStart();
+            int insertIndex = GetAfterSelectInsertPoint(sqlFragment);
+            if (insertIndex > 0)
+            {
+              string newFragment = string.Empty;
+
+              if (offset > 0)
+              {
+                newFragment = sqlFragment.Insert(insertIndex, " first " + limit.ToString() + " skip " + offset.ToString());
+              }
+              else
+              {
+                newFragment = sqlFragment.Insert(insertIndex, " first " + limit.ToString());
+              }
+              pagingBuilder.Add(newFragment);
+              firstAdded = true;
+              continue;
+            }
+          }
+        }
+        pagingBuilder.AddObject(sqlPart);
+      }
+
+      return pagingBuilder.ToSqlString();
+    }
+
+    public override bool SupportsVariableLimit
+    {
+      get { return false; }
+    }
+
 		public override string ForUpdateString
 		{
 			get { return " with lock"; }
@@ -164,5 +227,19 @@
 		{
 			return " for update of " + aliases + " with lock";
 		}
+
+    private static int GetAfterSelectInsertPoint(string fragment)
+    {
+      string fragmentLowerCased = fragment.ToLower(System.Globalization.CultureInfo.InvariantCulture);
+      if (fragmentLowerCased.StartsWith("select distinct"))
+      {
+        return 15;
+      }
+      else if (fragmentLowerCased.StartsWith("select"))
+      {
+        return 6;
+      }
+      return 0;
+    }
 	}
 }
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