mysql Rand() not working -


In my case I need to first display special items, apart from that I have to choose randomly. So I have used the following query 

  "SELECT * table_test1 WHERE id = 3 UNION (SELECT * FROM table_test1 WHERE id << ORDER BY RAND ())"   
 but this randomly  
 my table  
  ID name 1A2B3C4D5E  < /  
 It always selects CABDE  
 Can anyone explain the principle of a union?  
 What's wrong   
 
 
 use  
  In the case of ORDER from SELECT * table_test1 when the id = 3 THEN -1 ELSE RAND () END   
, in the quote comment, in the second statement  ORDER BY  Has been completely ignored.  
 That means if you want the whole result to be sorted by a certain sequence then you need the  order , which is applicable to the whole query anyway or your solution Depending on the assumptions, implementation may break into future versions.

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