mysql數據庫時間查詢

1、查詢當前時間  年月日時分秒

mysql> select now();
+---------------------+
| now()               |
+---------------------+
| 2018-03-19 23:12:52 |
+---------------------+

2、查詢當前時間 前三小時 的時間點

mysql> select subdate(now(),interval 3 hour);
+--------------------------------+
| subdate(now(),interval 3 hour) |
+--------------------------------+
| 2018-03-19 20:13:11            |
+--------------------------------+

3、查詢當前時間  前三天 的時間點

mysql> select subdate(now(),interval 3 day);
+-------------------------------+
| subdate(now(),interval 3 day) |
+-------------------------------+
| 2018-03-16 23:13:23           |
+-------------------------------+

4、查新當前時間 前三分鍾 的時間點

mysql> select subdate(now(),interval 3 minute);
+----------------------------------+
| subdate(now(),interval 3 minute) |
+----------------------------------+
| 2018-03-19 23:10:32              |
+----------------------------------+

5、查詢當前時間  時分秒

mysql> select current_time();
+----------------+
| current_time() |
+----------------+
| 23:14:09       |
+----------------+

6、查詢當前時間  年月日時分秒

mysql> select current_date();
+----------------+
| current_date() |
+----------------+
| 2018-03-19     |
+----------------+

 7、獲取本月最后一天

mysql> select last_day(curdate());
+---------------------+
| last_day(curdate()) |
+---------------------+
| 2018-03-31          |
+---------------------+

8、獲取本月第一天

mysql> select date_add(curdate(), interval - day(curdate()) + 1 day);
+--------------------------------------------------------+
| date_add(curdate(), interval - day(curdate()) + 1 day) |
+--------------------------------------------------------+
| 2018-03-01                                             |
+--------------------------------------------------------+

9、獲取下個月第一天

mysql> select date_add(curdate() - day(curdate()) + 1, interval 1 month);
+------------------------------------------------------------+
| date_add(curdate() - day(curdate()) + 1, interval 1 month) |
+------------------------------------------------------------+
| 2018-04-01                                                 |
+------------------------------------------------------------+

10、獲取本月天數

mysql> select day(last_day(curdate()));
+--------------------------+
| day(last_day(curdate())) |
+--------------------------+
|                       31 |
+--------------------------+

11-1、獲取一個月前的今天【2018年的2月只有28天】

mysql> select date_sub(curdate(), interval 1 month);
+---------------------------------------+
| date_sub(curdate(), interval 1 month) |
+---------------------------------------+
| 2018-02-28                            |
+---------------------------------------+

11-1、獲取兩個月前的今天

mysql> select date_sub(curdate(), interval 2 month);
+---------------------------------------+
| date_sub(curdate(), interval 2 month) |
+---------------------------------------+
| 2018-01-29                            |
+---------------------------------------+

12、獲取當前時間【當前月的第幾天】

mysql> select datediff(curdate(), date_sub(curdate(), interval 1 month));
+------------------------------------------------------------+
| datediff(curdate(), date_sub(curdate(), interval 1 month)) |
+------------------------------------------------------------+
|                                                         29 |
+------------------------------------------------------------+

 13、以時間為條件查詢數據時(例如查詢某個月內或者固定時間段內的數據)

/*
           需要的依賴：
         <!-- https://mvnrepository.com/artifact/joda-time/joda-time -->
        <dependency>
            <groupId>joda-time</groupId>
            <artifactId>joda-time</artifactId>
            <version>2.9.9</version>
        </dependency>
         */
        //關於數據庫查詢數據以時間為條件的查詢時
        /*
            思路：將 將時間格式的字符串轉換為DateTime類型的時間，
            然后可以實現在該時間基礎上  plus增加day  month  week  year等等;
            然后將增加固定時間后得到的DateTime類型的時間轉換為字符串
            在sql語句中進行拼接
         */
        StringBuffer timeStr = new StringBuffer("2017-01");
        timeStr.append("-01 00:00:01");
        org.joda.time.format.DateTimeFormatter format = org.joda.time.format.DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss");
        //時間解析
        org.joda.time.DateTime startDate = DateTime.parse(timeStr.toString(), format);
        DateTime endDate = startDate.plusMonths(1);//在start表示的時間點基礎上增加一個月

        String start = startDate.toString("yyyy-MM-dd HH:mm:ss");
        String end = endDate.toString("yyyy-MM-dd HH:mm:ss");
        System.out.println(start);
        System.out.println(end);
        // 單引號一定不能省略
        StringBuffer sql = new StringBuffer("select * from user where create_time >'");
        sql.append( start).append("'").append(" and create_time < '").append(end).append("'");
        String sqlQuery = sql.toString();
        //總之就是如下" create_time < '2017-01-01 00；00:00'" (這個是2017-01-01 00；00:00String類型的參數)