mySql:count列中具有相同数据的行数

Question

我试图选择表中的所有内容,并计算表中具有相同数据的行数.

SELECT *, COUNT(thedate) daycount FROM `table` ORDER BY thedate DESC

我希望有一个查询输出与该日期相关的日期和行数,循环输出将是这样的:

2000年1月1日(2行)
col1,col2,col3,col4
col1,col2,col3,col4

2000年1月1日(3行)
col1,col2,col3,col4
col1,col2,col3,col4
col1,col2,col3,col4

2000年1月1日(6行)
col1,col2,col3,col4
col1,col2,col3,col4
col1,col2,col3,col4
col1,col2,col3,col4
col1,col2,col3,col4
col1,col2,col3,col4

等等...

这有意义吗？

Answer 1

如果您有一个如下所示的表：

CREATE TABLE yourtable
(
    datefield DATETIME,
    col1 VARCHAR(20),
    col2 INT NOT NULL,
    col3 TINYINT NOT NULL,
    col4 CHAR(5)
);

并且您想要每天重复的 col1.. col4 的计数，您将运行此查询

SELECT
    COUNT(datefield) datefield_count,
    LEFT(all_fields,10) datefield,
    SUBSTR(all_fields,11) all_other_fields
FROM
(
    SELECT
        DATE(datefield) datefield,
        CONCAT(DATE(datefield),'|',
        COALESCE(col1,'< NULL >'),'|',
        COALESCE(col2,'< NULL >'),'|',
        COALESCE(col3,'< NULL >'),'|',
        COALESCE(col4,'< NULL >'),'|') all_fields
    FROM
         yourtable
) A
GROUP BY all_fields;

以下是一些示例数据和查询结果：

mysql> DROP TABLE IF EXISTS yourtable;
Query OK, 0 rows affected (0.04 sec)

mysql> CREATE TABLE yourtable
    -> (
    ->     datefield DATETIME,
    ->     col1 VARCHAR(20),
    ->     col2 INT,
    ->     col3 TINYINT,
    ->     col4 CHAR(5)
    -> );
Query OK, 0 rows affected (0.11 sec)

mysql> INSERT INTO yourtable VALUES
    -> (DATE(NOW() - INTERVAL 1 DAY),'rolando',4,3   ,'angel'),
    -> (DATE(NOW() - INTERVAL 1 DAY),'rolando',4,3   ,'angel'),
    -> (DATE(NOW() - INTERVAL 1 DAY),'rolando',4,3   ,'angel'),
    -> (DATE(NOW() - INTERVAL 1 DAY),'rolando',4,NULL,'angel'),
    -> (DATE(NOW() - INTERVAL 1 DAY),'rolando',4,NULL,'angel'),
    -> (DATE(NOW() - INTERVAL 2 DAY),'rolando',4,2   ,'angel'),
    -> (DATE(NOW() - INTERVAL 2 DAY),'rolando',4,2   ,'angel'),
    -> (DATE(NOW() - INTERVAL 2 DAY),'rolando',4,2   ,'angel'),
    -> (DATE(NOW() - INTERVAL 2 DAY),'rolando',4,2   ,'angel'),
    -> (DATE(NOW() - INTERVAL 2 DAY),'rolando',4,NULL,'edwards'),
    -> (DATE(NOW() - INTERVAL 2 DAY),'rolando',4,NULL,'angel'),
    -> (DATE(NOW() - INTERVAL 3 DAY),'rolando',5,2   ,'angel'),
    -> (DATE(NOW() - INTERVAL 3 DAY),'rolando',5,2   ,'angel'),
    -> (DATE(NOW() - INTERVAL 3 DAY),'rolando',4,2   ,'angel'),
    -> (DATE(NOW() - INTERVAL 3 DAY),'pamela' ,4,2   ,'angel'),
    -> (DATE(NOW() - INTERVAL 3 DAY),'pamela' ,4,NULL,'edwards'),
    -> (DATE(NOW() - INTERVAL 3 DAY),'pamela' ,5,2   ,'angel'),
    -> (DATE(NOW() - INTERVAL 3 DAY),'pamela' ,5,2   ,'angel'),
    -> (DATE(NOW() - INTERVAL 3 DAY),'rolando',4,2   ,'angel'),
    -> (DATE(NOW() - INTERVAL 3 DAY),'rolando',4,2   ,'angel'),
    -> (DATE(NOW() - INTERVAL 3 DAY),'rolando',4,NULL,'edwards'),
    -> (DATE(NOW() - INTERVAL 3 DAY),'rolando',4,NULL,'angel')
    -> ;
Query OK, 22 rows affected, 3 warnings (0.03 sec)
Records: 22  Duplicates: 0  Warnings: 3

mysql> SELECT * FROM yourtable;
+---------------------+---------+------+------+-------+
| datefield           | col1    | col2 | col3 | col4  |
+---------------------+---------+------+------+-------+
| 2011-06-30 00:00:00 | rolando |    4 |    3 | angel |
| 2011-06-30 00:00:00 | rolando |    4 |    3 | angel |
| 2011-06-30 00:00:00 | rolando |    4 |    3 | angel |
| 2011-06-30 00:00:00 | rolando |    4 | NULL | angel |
| 2011-06-30 00:00:00 | rolando |    4 | NULL | angel |
| 2011-06-29 00:00:00 | rolando |    4 |    2 | angel |
| 2011-06-29 00:00:00 | rolando |    4 |    2 | angel |
| 2011-06-29 00:00:00 | rolando |    4 |    2 | angel |
| 2011-06-29 00:00:00 | rolando |    4 |    2 | angel |
| 2011-06-29 00:00:00 | rolando |    4 | NULL | edwar |
| 2011-06-29 00:00:00 | rolando |    4 | NULL | angel |
| 2011-06-28 00:00:00 | rolando |    5 |    2 | angel |
| 2011-06-28 00:00:00 | rolando |    5 |    2 | angel |
| 2011-06-28 00:00:00 | rolando |    4 |    2 | angel |
| 2011-06-28 00:00:00 | pamela  |    4 |    2 | angel |
| 2011-06-28 00:00:00 | pamela  |    4 | NULL | edwar |
| 2011-06-28 00:00:00 | pamela  |    5 |    2 | angel |
| 2011-06-28 00:00:00 | pamela  |    5 |    2 | angel |
| 2011-06-28 00:00:00 | rolando |    4 |    2 | angel |
| 2011-06-28 00:00:00 | rolando |    4 |    2 | angel |
| 2011-06-28 00:00:00 | rolando |    4 | NULL | edwar |
| 2011-06-28 00:00:00 | rolando |    4 | NULL | angel |
+---------------------+---------+------+------+-------+
22 rows in set (0.00 sec)

mysql> SELECT
    ->     COUNT(datefield) datefield_count,
    ->     LEFT(all_fields,10) datefield,
    ->     SUBSTR(all_fields,11) all_other_fields
    -> FROM
    -> (
    ->     SELECT
    ->         DATE(datefield) datefield,
    ->         CONCAT(DATE(datefield),'|',
    ->         COALESCE(col1,'< NULL >'),'|',
    ->         COALESCE(col2,'< NULL >'),'|',
    ->         COALESCE(col3,'< NULL >'),'|',
    ->         COALESCE(col4,'< NULL >'),'|') all_fields
    ->     FROM
    ->          yourtable
    -> ) A
    -> GROUP BY all_fields;
+-----------------+------------+----------------------------+
| datefield_count | datefield  | all_other_fields           |
+-----------------+------------+----------------------------+
|               1 | 2011-06-28 | |pamela|4|2|angel|         |
|               1 | 2011-06-28 | |pamela|4|< NULL >|edwar|  |
|               2 | 2011-06-28 | |pamela|5|2|angel|         |
|               3 | 2011-06-28 | |rolando|4|2|angel|        |
|               1 | 2011-06-28 | |rolando|4|< NULL >|angel| |
|               1 | 2011-06-28 | |rolando|4|< NULL >|edwar| |
|               2 | 2011-06-28 | |rolando|5|2|angel|        |
|               4 | 2011-06-29 | |rolando|4|2|angel|        |
|               1 | 2011-06-29 | |rolando|4|< NULL >|angel| |
|               1 | 2011-06-29 | |rolando|4|< NULL >|edwar| |
|               3 | 2011-06-30 | |rolando|4|3|angel|        |
|               2 | 2011-06-30 | |rolando|4|< NULL >|angel| |
+-----------------+------------+----------------------------+
12 rows in set (0.00 sec)

mysql>

我将把它留给你富有想象力的创造力来循环和打印

• 日期字段
• 日期字段计数
• 打印 all_other_fields 'datefield_count' 次

试一试 ！！！