Question

How can I request a random row (or as close to truly random as possible) in pure SQL?

Answer 1

See this post: SQL to Select a random row from a database table. It goes through methods for doing this in MySQL, PostgreSQL, Microsoft SQL Server, IBM DB2 and Oracle (the following is copied from that link):

Select a random row with MySQL:

SELECT column FROM table ORDER BY RAND() LIMIT 1 

Select a random row with PostgreSQL:

SELECT column FROM table ORDER BY RANDOM() LIMIT 1 

Select a random row with Microsoft SQL Server:

SELECT TOP 1 column FROM table ORDER BY NEWID() 

Select a random row with IBM DB2

SELECT column, RAND() as IDX  FROM table  ORDER BY IDX FETCH FIRST 1 ROWS ONLY 

Select a random record with Oracle:

SELECT column FROM ( SELECT column FROM table ORDER BY dbms_random.value ) WHERE rownum = 1