Introduce postgresql::remove_from with optional returning clause (#538)

include/sqlpp11/postgresql/postgresql.h

@@ -32,4 +32,5 @@
 #include <sqlpp11/postgresql/connection_pool.h>
 #include <sqlpp11/postgresql/exception.h>
 #include <sqlpp11/postgresql/insert.h>
+#include <sqlpp11/postgresql/remove.h>
 #include <sqlpp11/postgresql/update.h>

include/sqlpp11/postgresql/remove.h

@@ -0,0 +1,65 @@
+#pragma once
+
+/**
+ * Copyright (c) 2023-2023, Roland Bock
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ *   Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ *   Redistributions in binary form must reproduce the above copyright notice, this
+ *   list of conditions and the following disclaimer in the documentation and/or
+ *   other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sqlpp11/remove.h>
+#include <sqlpp11/postgresql/returning.h>
+
+namespace sqlpp
+{
+  namespace postgresql
+  {
+    template <typename Database>
+    using blank_remove_t = statement_t<Database, remove_t, no_from_t, no_using_t, no_where_t<true>, no_returning_t>;
+
+    inline auto remove() -> blank_remove_t<void>
+    {
+      return {};
+    }
+
+    template <typename Table>
+    auto remove_from(Table table) -> decltype(blank_remove_t<void>().from(table))
+    {
+      return {blank_remove_t<void>().from(table)};
+    }
+
+    template <typename Database>
+    auto dynamic_remove(const Database& /*unused*/) -> decltype(blank_remove_t<Database>())
+    {
+      static_assert(std::is_base_of<connection, Database>::value, "Invalid database parameter");
+      return {blank_remove_t<Database>()};
+    }
+
+    template <typename Database, typename Table>
+    auto dynamic_remove_from(const Database& /*unused*/, Table table)
+        -> decltype(blank_remove_t<Database>().from(table))
+    {
+      static_assert(std::is_base_of<connection, Database>::value, "Invalid database parameter");
+      return {blank_remove_t<Database>().from(table)};
+    }
+  }  // namespace postgresql
+}  // namespace sqlpp

tests/postgresql/usage/Returning.cpp

@@ -45,6 +45,11 @@ int Returning(int, char*[])
     for (const auto& row : updated)
       std::cout << "Gamma: " << row.gamma << " Beta: " << row.beta << std::endl;
 
+    auto removed =
+        db(sqlpp::postgresql::remove_from(foo).where(foo.beta == 0).returning(foo.gamma, foo.beta));
+    for (const auto& row : removed)
+      std::cout << "Gamma: " << row.gamma << " Beta: " << row.beta << std::endl;
+
     auto multi_insert = sqlpp::postgresql::insert_into(foo).columns(foo.beta).returning(foo.alpha, foo.beta);
     multi_insert.values.add(foo.beta = 1);
     multi_insert.values.add(foo.beta = 2);