我有這條簡(jiǎn)單的線：var records = db.MyDbTable.Where(x => x.SupplierId.HasValue).ToList();而且執(zhí)行需要一個(gè)小時(shí)。我表中有272行。該表有一列，NVARCHAR(MAX)里面有巨大的字符串。如何優(yōu)化語句？之后在代碼中，我有一個(gè)foreach，它會(huì)遍歷記錄并對(duì)其進(jìn)行處理。db中的select語句需要5分鐘。當(dāng)我使用SQL事件探查器進(jìn)行檢查時(shí)，這是從C＃轉(zhuǎn)換而來的語句：SELECT     [Extent1].[id] AS [id],     [Extent1].[xml] AS [xml],     [Extent1].[name] AS [name],     [Extent1].[create] AS [create],     [Extent1].[sale] AS [sale],     [Extent1].[SupplierId] AS [SupplierId],     [Extent1].[Success] AS [Success],     [Extent1].[IId] AS [IId]    FROM [dbo].[MyDbTable] AS [Extent1]    WHERE [Extent1].[SupplierId] IS NOT NULL