From 3b9fabfc20089fe9e9279a287c1db5bb37a6d275 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Tue, 3 Sep 2013 12:49:14 +0200
Subject: Handling of dynamic empty statements as result of versioning

---
 odb/pgsql/statement.cxx |  6 ++++++
 odb/pgsql/statement.hxx | 11 +++++++++++
 2 files changed, 17 insertions(+)

diff --git a/odb/pgsql/statement.cxx b/odb/pgsql/statement.cxx
index b65eb5b..eea3c39 100644
--- a/odb/pgsql/statement.cxx
+++ b/odb/pgsql/statement.cxx
@@ -187,6 +187,12 @@ namespace odb
         text_ = text_copy_.c_str ();
       }
 
+      if (empty ())
+      {
+        deallocated_ = true;
+        return;
+      }
+
       {
         odb::tracer* t;
         if ((t = conn_.transaction_tracer ()) ||
diff --git a/odb/pgsql/statement.hxx b/odb/pgsql/statement.hxx
index 4cc1f42..6c6095c 100644
--- a/odb/pgsql/statement.hxx
+++ b/odb/pgsql/statement.hxx
@@ -50,6 +50,17 @@ namespace odb
         return conn_;
       }
 
+      // A statement can be empty. This is used to handle situations
+      // where a SELECT or UPDATE statement ends up not having any
+      // columns after processing. An empty statement cannot be
+      // executed.
+      //
+      bool
+      empty () const
+      {
+        return *text_ == '\0';
+      }
+
       void
       deallocate ();
 
-- 
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