有没有一种简单的方法可以从具有特定条件的数据表中选择随机记录（大约 20 条）

Question

Here is the code I used

SELECT * FROM   
(SELECT * FROM [table name] 
ORDER BY dbms_random.value)
WHERE rownum < 10

I would like to select random rows only from records with column A = XYZ. I tried to add a WHERE clause in the code:

SELECT * FROM   
(SELECT * FROM [table name] 
WHERE [column A] = 'XYZ'
ORDER BY dbms_random.value)
WHERE rownum < 10

but got an error. Any feedback would be greatly appreciated.

Answer 1

You can try the below approach in SQL Server:

SELECT TOP 10 * FROM [table name] 
WHERE [column A] = 'XYZ'
ORDER BY newid()

More information on how ORDER BY newid() works in a SO post

Answer 2

Your code looks like Oracle code. It does not recognize square braces for identifiers. In fact, don't escape them -- or use double quotes if you must:

SELECT t.*   
FROM (SELECT t.*
      FROM t 
      WHERE columnA = 'XYZ'
      ORDER BY dbms_random.value
     ) t
WHERE rownum < 10;

In SQL Server, the equivalent would be:

SELECT TOP (10) t.*
FROM t 
WHERE columnA = 'XYZ'
ORDER BY NEWID()