仅从 MySQL 中的日期时间 (YYYY-MM-DD HH:MM:SS) 中选择不同的日期

Question

Executing this command brings me the following (all the dates from all columns, so it essentially did the same thing as SELECT date without distinct):

SELECT DISTINCT date FROM daily ORDER BY date DESC

2013-02-12 16:40:52
2013-02-06 11:48:49
2013-02-06 11:36:41
2013-02-06 11:35:59
2013-02-04 19:38:12
2013-02-04 18:12:30
2013-02-04 09:58:41
2013-02-04 09:43:01
2013-02-04 09:35:51
2013-02-04 09:30:22
2013-02-04 09:24:57
2013-02-04 09:21:09
2013-02-04 08:50:13

What I need:

2013-02-12
2013-02-06
2013-02-04

1. Is there any way to alter my date table and convert it to YYYY-MM-DD instead?

2. If not, is there a way to select distinct dates based only on the day?

Answer 1

mysql> select DATE_FORMAT(Current_Timestamp, '%c %d %Y') from dual;
+--------------------------------------------+
| DATE_FORMAT(Current_Timestamp, '%c %d %Y') |
+--------------------------------------------+
| 2 12 2013                                  |
+--------------------------------------------+
1 row in set (0.01 sec)

mysql> 

of course you would be using your 'daily' table.

mysql> select DATE_FORMAT(Date, '%c %d %Y') from daily;

or maybe you want

mysql> select * from daily group by DATE_FORMAT(Date, '%c %d %Y');

Answer 2

Try this one:

SELECT DISTINCT(CONVERT(VARCHAR, CONVERT(DATETIME,[DATE]),23)) AS DT  
FROM DAILY
ORDER BY DT ASC

Answer 3

我发现在大于 N 百万的大型数据集上，按 DATE_FORMAT 分组可能比使用慢 10-20%；

 GROUP BY someid,year(date),month(date),day(date)

Answer 4

So I have just added a small part to sgeddes answer which was close to working for me but I had to as the : AS date_change so I can list the values.

$sql = "SELECT DISTINCT DATE_FORMAT(yourdate, '%Y-%m-%d') as date_change FROM 
daily ORDER BY (yourdate) DESC LIMIT 10";
$result = $conn->query($sql);

if ($result->num_rows > 0) {

 // output data of each row
 while($row = $result->fetch_assoc()) {
 $test = $row['date_change'];
    echo $test.'<br>';



  }

} else {
echo "0 results";
}

Answer 5

Its very simple use DATE() function.

Example:

SELECT DISTINCT DATE(date)
    FROM daily
    ORDER BY date
    DESC

Answer 6

For MySQL, you can use DATE(date) to return just the date. If you want to format it, use DATE_FORMAT :

SELECT DISTINCT DATE_FORMAT(yourdate, '%Y-%m-%d') 
FROM daily ORDER BY DATE(yourdate) DESC

You cannot change the way the database stores these values.

And here is the fiddle: http://sqlfiddle.com/#!2/f50527/6

Answer 7

In Access DB

SELECT DISTINCT Format(date, 'Short Date')
  FROM daily
 ORDER BY Format(date, 'Short Date') DESC;