-- PostgreSQL
SELECT
    t1."ParentID",
    t1."ChildID"
FROM
    "Child" t1
ORDER BY
    t1."ChildID" DESC
LIMIT 5 OFFSET 2 


-- SQLite
SELECT
    [t1].[ParentID],
    [t1].[ChildID]
FROM
    [Child] [t1]
ORDER BY
    [t1].[ChildID] DESC
LIMIT 5 OFFSET 2

there is a misunderstanding. sqlpp11 is not an abstraction layer or an ORM. It just offers a different way of expression SQL statements. You still have to deal with all the gory details like how to join your tables, which condition to put into the WHERE and which condition to put into the HAVING part, for example. sqlpp11 does not relieve you of any of those decisions.

I>>Тебе дали целый вагон таких примеров, но ты до сих пор этого не заметил

there is a misunderstanding. sqlpp11 is not an abstraction layer or an ORM. It just offers a different way of expression SQL statements.

You still have to deal with all the gory details like how to join your tables, which condition to put into the WHERE and which condition to put into the HAVING part, for example. sqlpp11 does not relieve you of any of those decisions.

SET @s = 'SELECT SQRT(POW(?,2) + POW(?,2)) AS hypotenuse';
PREPARE stmt2 FROM @s;
SET @a = 6;
SET @b = 8;
EXECUTE stmt2 USING @a, @b;
DEALLOCATE PREPARE stmt2;

var q =
    from c in categories
    join p in products on c equals p.Category into ps
    from p in ps.DefaultIfEmpty()
    select new { Category = c, ProductName = p == null ? "(No products)" : p.ProductName };

Hibernate Query Language (HQL) is an object-oriented query language, similar to SQL, but instead of operating on tables and columns, HQL works with persistent objects and their properties

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data.SqlClient;
using System.Diagnostics;
using System.Linq;

using DataModels;

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            var sw = new Stopwatch();

            LinqTest(sw);
            AdoTest(sw);

            var n = LinqTest(sw);
            Console.WriteLine("LINQ: {0} in {1}", n, sw.Elapsed);

            n = AdoTest(sw);
            Console.WriteLine("ADO:  {0} in {1}", n, sw.Elapsed);
        }

        static int LinqTest(Stopwatch sw)
        {
            sw.Reset();

            var count = 0;

            using (var ctx = new NorthwindDB())
            {
                for (var i = 0; i < 10000; i++)
                {
                    sw.Start();

                    var list =
                    (
                        from o in ctx.Orders
                        join c in ctx.Customers on o.CustomerID equals c.CustomerID
                        select new { o.OrderID, o.OrderDate, c.Country, c.CompanyName }
                    ).Take(10).ToList();

                    sw.Stop();

                    count += list.Count;
                }
            }

            return count;
        }

        static int AdoTest(Stopwatch sw)
        {
            sw.Reset();

            var count = 0;

            using (var con = new SqlConnection(ConfigurationManager.ConnectionStrings["Northwind"].ConnectionString))
            {
                con.Open();

                for (var i = 0; i < 10000; i++)
                {
                    sw.Start();

                    var list = new List<object>();

                    using (var cmd = new SqlCommand(@"
                        SELECT TOP (10)
                            [o].[OrderID],
                            [o].[OrderDate],
                            [c].[Country],
                            [c].[CompanyName]
                        FROM
                            [dbo].[Orders] [o]
                                INNER JOIN [dbo].[Customers] [c] ON [o].[CustomerID] = [c].[CustomerID]", con))
                    {
                        using (var reader = cmd.ExecuteReader())
                        {
                            if (reader.HasRows)
                            {
                                while (reader.Read())
                                {
                                    list.Add(new
                                    {
                                        OrderID     = (int)reader["OrderID"],
                                        OrderDate   = (DateTime)reader["OrderDate"],
                                        Country     = (string)reader["Country"],
                                        CompanyName = (string)reader["CompanyName"],
                                    });
                                }
                            }
                        }
                    }

                    sw.Stop();

                    count += list.Count;
                }
            }

            return count;
        }
    }
}

LINQ: 100000 in 00:00:05.7321425
ADO:  100000 in 00:00:05.5328326

-- Access
SELECT TOP 7
    [t1].[ParentID],
    [t1].[ChildID]
FROM
    [Child] [t1]
ORDER BY
    [t1].[ChildID] DESC


-- DB2 DB2.LUW DB2LUW
SELECT *
FROM
(
    SELECT
        t.*,
        ROW_NUMBER() OVER() as rn
    FROM
    (
        SELECT
            "t1"."ParentID",
            "t1"."ChildID"
        FROM
            "Child" "t1"
        ORDER BY
            "t1"."ChildID" DESC
    ) t
) t2
WHERE
    t2.rn BETWEEN 3 AND 7


-- Firebird
SELECT FIRST 5 SKIP 2
    t1.ParentID,
    t1.ChildID
FROM
    Child t1
ORDER BY
    t1.ChildID DESC


-- Informix
SELECT SKIP 2 FIRST 5
    t1.ParentID,
    t1.ChildID
FROM
    Child t1
ORDER BY
    t1.ChildID DESC


-- MariaDB MySql
SELECT
    `t1`.`ParentID`,
    `t1`.`ChildID`
FROM
    `Child` `t1`
ORDER BY
    `t1`.`ChildID` DESC
LIMIT 2,5


-- MySql
SELECT
    `t1`.`ParentID`,
    `t1`.`ChildID`
FROM
    `Child` `t1`
ORDER BY
    `t1`.`ChildID` DESC
LIMIT 2,5


-- Oracle.Native Oracle
SELECT t2.*
FROM
(
    SELECT t.*, ROWNUM as rn
    FROM
    (
        SELECT
            t1.ParentID,
            t1.ChildID
        FROM
            Child t1
        ORDER BY
            t1.ChildID DESC
    ) t
    WHERE
        ROWNUM <= 7
) t2
WHERE
    t2.rn > 2


-- PostgreSQL PostgreSQL.9.3 PostgreSQL
SELECT
    t1."ParentID",
    t1."ChildID"
FROM
    "Child" t1
ORDER BY
    t1."ChildID" DESC
LIMIT 5 OFFSET 2 


-- SQLite
SELECT
    [t1].[ParentID],
    [t1].[ChildID]
FROM
    [Child] [t1]
ORDER BY
    [t1].[ChildID] DESC
LIMIT 5 OFFSET 2


-- SqlAzure.2012 SqlServer.2012
SELECT
    [t1].[ParentID],
    [t1].[ChildID]
FROM
    [Child] [t1]
ORDER BY
    [t1].[ChildID] DESC
OFFSET 2 ROWS FETCH NEXT 5 ROWS ONLY 


-- SqlCe
SELECT
    [t1].[ParentID],
    [t1].[ChildID]
FROM
    [Child] [t1]
ORDER BY
    [t1].[ChildID] DESC
OFFSET 2 ROWS FETCH NEXT 5 ROWS ONLY 


-- SqlServer.2005
SELECT *
FROM
(
    SELECT
        t.*,
        ROW_NUMBER() OVER
        (
            ORDER BY
                oby DESC
        ) as rn
    FROM
    (
        SELECT
            [t1].[ParentID],
            [t1].[ChildID],
            [t1].[ChildID] as [oby]
        FROM
            [Child] [t1]
    ) t
) t2
WHERE
    t2.rn BETWEEN 3 AND 7


-- SqlServer.2008
SELECT *
FROM
(
    SELECT
        t.*,
        ROW_NUMBER() OVER
        (
            ORDER BY
                oby DESC
        ) as rn
    FROM
    (
        SELECT
            [t1].[ParentID],
            [t1].[ChildID],
            [t1].[ChildID] as [oby]
        FROM
            [Child] [t1]
    ) t
) t2
WHERE
    t2.rn BETWEEN 3 AND 7


-- SqlServer.2012
SELECT
    [t1].[ParentID],
    [t1].[ChildID]
FROM
    [Child] [t1]
ORDER BY
    [t1].[ChildID] DESC
OFFSET 2 ROWS FETCH NEXT 5 ROWS ONLY 


-- SqlServer.2014 SqlServer.2012
SELECT
    [t1].[ParentID],
    [t1].[ChildID]
FROM
    [Child] [t1]
ORDER BY
    [t1].[ChildID] DESC
OFFSET 2 ROWS FETCH NEXT 5 ROWS ONLY 


-- Sybase
SELECT TOP 7
    [t1].[ParentID],
    [t1].[ChildID]
FROM
    [Child] [t1]
ORDER BY
    [t1].[ChildID] DESC