對結果進行排序

SQL 對結果進行排序

SQL ORDER BY 子句根據(jù)一列或者多列的值，按照升序或者降序排列數(shù)據(jù)。某些數(shù)據(jù)庫默認以升序排列查詢結果。

語法：

用于將結果按照升序或者降序排列的 ORDER BY 子句的基本語法如下所示：

    SELECT column-list 
    FROM table_name 
    [WHERE condition] 
    [ORDER BY column1, column2, .. columnN] [ASC | DESC];

ORDER BY 子句可以同時使用多個列作為排序條件。無論用哪一列作為排序條件，都要確保該列在存在。

示例：

考慮含有如下所示記錄的 CUSTOMERS 表：

    +----+----------+-----+-----------+----------+
    | ID | NAME     | AGE | ADDRESS   | SALARY   |
    +----+----------+-----+-----------+----------+
    |  1 | Ramesh   |  32 | Ahmedabad |  2000.00 |
    |  2 | Khilan   |  25 | Delhi     |  1500.00 |
    |  3 | kaushik  |  23 | Kota      |  2000.00 |
    |  4 | Chaitali |  25 | Mumbai    |  6500.00 |
    |  5 | Hardik   |  27 | Bhopal    |  8500.00 |
    |  6 | Komal    |  22 | MP        |  4500.00 |
    |  7 | Muffy    |  24 | Indore    | 10000.00 |
    +----+----------+-----+-----------+----------+

下面的例子將查詢結果按照 NAME 和 SALARY 升序排列：

    SQL> SELECT * FROM CUSTOMERS
         ORDER BY NAME, SALARY;

結果如下所示：

    +----+----------+-----+-----------+----------+
    | ID | NAME     | AGE | ADDRESS   | SALARY   |
    +----+----------+-----+-----------+----------+
    |  4 | Chaitali |  25 | Mumbai    |  6500.00 |
    |  5 | Hardik   |  27 | Bhopal    |  8500.00 |
    |  3 | kaushik  |  23 | Kota      |  2000.00 |
    |  2 | Khilan   |  25 | Delhi     |  1500.00 |
    |  6 | Komal    |  22 | MP        |  4500.00 |
    |  7 | Muffy    |  24 | Indore    | 10000.00 |
    |  1 | Ramesh   |  32 | Ahmedabad |  2000.00 |
    +----+----------+-----+-----------+----------+

下面的例子將查詢結果按照 NAME 降序排列：

    SQL> SELECT * FROM CUSTOMERS
         ORDER BY NAME DESC;

結果如下所示：

    +----+----------+-----+-----------+----------+
    | ID | NAME     | AGE | ADDRESS   | SALARY   |
    +----+----------+-----+-----------+----------+
    |  1 | Ramesh   |  32 | Ahmedabad |  2000.00 |
    |  7 | Muffy    |  24 | Indore    | 10000.00 |
    |  6 | Komal    |  22 | MP        |  4500.00 |
    |  2 | Khilan   |  25 | Delhi     |  1500.00 |
    |  3 | kaushik  |  23 | Kota      |  2000.00 |
    |  5 | Hardik   |  27 | Bhopal    |  8500.00 |
    |  4 | Chaitali |  25 | Mumbai    |  6500.00 |
    +----+----------+-----+-----------+----------+

以自定義的方式排序查詢結果的 SELECT 語句如下所示：

    SQL> SELECT * FROM CUSTOMERS
        ORDER BY (CASE ADDRESS
        WHEN 'DELHI'     THEN 1
        WHEN 'BHOPAL'    THEN 2
        WHEN 'KOTA'      THEN 3
        WHEN 'AHMADABAD' THEN 4
        WHEN 'MP'   THEN 5
        ELSE 100 END) ASC, ADDRESS DESC;

結果如下所示：

    +----+----------+-----+-----------+----------+
    | ID | NAME     | AGE | ADDRESS   | SALARY   |
    +----+----------+-----+-----------+----------+
    |  2 | Khilan   |  25 | Delhi     |  1500.00 |
    |  5 | Hardik   |  27 | Bhopal    |  8500.00 |
    |  3 | kaushik  |  23 | Kota      |  2000.00 |
    |  6 | Komal    |  22 | MP        |  4500.00 |
    |  4 | Chaitali |  25 | Mumbai    |  6500.00 |
    |  7 | Muffy    |  24 | Indore    | 10000.00 |
    |  1 | Ramesh   |  32 | Ahmedabad |  2000.00 |
    +----+----------+-----+-----------+----------+

這樣查詢結果就會先以你所定義的順序按照 ADDRESS 排列。對于其余的 ADDRESS 值，查詢結果仍然按照自然方式排列。亦即，除列出的 ADDERSS 之外，其余的 ADDRESS 按照字母表的逆序排列。