dynamic pivot product groups, with zero's, Sql Server

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CREATE TABLE OrderLines
    (
      LineId INT IDENTITY(1,1) PRIMARY KEY,
      OrderNo INT NOT NULL,
      ProductId INT NOT NULL,
      ProductGroupId INT NOT NULL,
      Quantity INT NOT NULL DEFAULT 0
    );

INSERT INTO OrderLines
    (OrderNo, ProductId, ProductGroupId, Quantity) VALUES
    (1, 1, 1, 5),
    (1, 2, 2, 3),
    (2, 1, 1, 5),
    (3, 3, 1, 1),
    (3, 1, 1, 5),
    (4, 3, 1, 4),
    (999, 16, 12, 4);

--
    -- Calculate the colums for the select
    --
    DECLARE @ColsSelect NVARCHAR(MAX);
    SELECT @ColsSelect = CONCAT(@ColsSelect+', '+char(10), 'ISNULL(', QUOTENAME(ProductGroupId), ',0) ', QUOTENAME(CONCAT('Group ', ProductGroupId)))
    FROM OrderLines
    GROUP BY ProductGroupId
    ORDER BY ProductGroupId;
    -- select @ColsSelect as ColsSelect;
    
    --
    -- Calculate the colums for the pivot
    --
    DECLARE @ColsPivot NVARCHAR(MAX);
    SELECT @ColsPivot = CONCAT(@ColsPivot+', ', QUOTENAME(ProductGroupId))
    FROM OrderLines
    GROUP BY ProductGroupId
    ORDER BY ProductGroupId;
    -- select @ColsPivot as ColsPivot;

--
    -- Generate the query string
    --
    DECLARE @DynSql NVARCHAR(MAX);
    SET @DynSql = CONCAT(N'SELECT OrderNo,', char(10), 
    @ColsSelect, char(10),
    N'FROM (', char(10),
    N'SELECT OrderNo, ProductGroupId, SUM(Quantity) AS Quantity ', char(10),
    N'FROM OrderLines ', char(10),
    N'GROUP BY OrderNo, ProductGroupId) Src ', char(10),
    N'PIVOT (SUM(Quantity) FOR ProductGroupId IN (',
    @ColsPivot,
    N')) Pvt ', char(10),
    N'ORDER BY OrderNo');
    -- select @DynSql as DynSql;

EXEC sp_executesql @DynSql;

View schema
Execution time: 0,11 sec, rows selected: 12, rows affected: 7, absolute service time: 0,7 sec, absolute service time: 0,71 sec