如何從訪問表中選擇700條隨機記錄？

Question

這段代碼給了我最後的700條記錄，而不是700條隨機記錄。

private string strsqlcommandBeta = " select top 700 LEFT(patronvalue17, INSTR(30, patronvalue17, ' ') -1) as patronvalue1, Rnd([objectid]) AS Ran from objectaer " + 
" order by objectdate desc" + 
" "; 

Answer 1

我不是附近的MS Access，但是這給了一槍：

SELECT * FROM (
    SELECT top 700 LEFT(patronvalue17, INSTR(30, patronvalue17, ' ') -1) as patronvalue1, objectdate 
    FROM objectaer 
    ORDER BY Rnd([objectid])() 
) order by objectdate desc 

中RND（[OBJECTID]）應該給你一個隨機數，通過什麼樣的排序，那麼你你想在那之後。

Answer 2

SELECT * FROM (
    SELECT top 700 LEFT(patronvalue17, INSTR(30, patronvalue17, ' ') -1) as patronvalue1, objectdate 
    FROM objectaer 
    ORDER BY newid() 
) order by objectdate desc 

的newid()函數生成其可以爲了排序的表中使用，得到在每次運行時不同結果的隨機GUID。我不知道你是否真的需要外部選擇，它是用來按日期排序隨機項目的降序