MYSQL选择查询使用where子句

Question

我有表

  
itemuid | category 
----------------------------- 
1   | 3 
2   | 3 
3   | 21 
4   | 3 
5   | 3 
6   | 21 
7   | 3 
----------------------------- 

我现在想itemuid5前选择itemuid与category21。 itemuid是我需要向后搜索的唯一信息。

任何人都可以告诉我select和where查询必须看起来像吗？谢谢。

Answer 1

如果我正确理解你，这应该工作：

SELECT itemuid FROM table_name WHERE category=21 and itemuid < 5 

Answer 2

如果 “前” 是指最大itemuid这仍然是小于5，则：

select max(itemuid) from tablename where itemuid < 5 and category = 21 

Answer 3

SELECT itemuid from notablenameinquestion where category=21 AND itemuid < 5 order by itemuid LIMIT 1; 

Answer 4

SELECT s.itemuid 
    FROM (SELECT itemuid 
      FROM yourTable 
      WHERE yourConditions 
      ORDER BY category DESC) s 
    WHERE ROWNUM = 1 

Answer 5

SELECT * FROM table 
    WHERE itemuid < 5 AND category = 21 
    ORDER BY itemuid DESC 
    LIMIT 1 

Answer 6

如果我理解正确：

Select Top(1) itemid from table_name where categoryid=21 and itemid<5