關於Mysql datetime類型存儲范圍測試

1. 創建一個datetime表

   > create table date_time(time datetime);
   > desc date_time;
   +-------+----------+------+-----+---------+-------+
   | Field | Type     | Null | Key | Default | Extra |
   +-------+----------+------+-----+---------+-------+
   | time  | datetime | YES  |     | NULL    |       |
   +-------+----------+------+-----+---------+-------+
   

2. 輸入"10000-10-10 00:00:00"進行測試

   > insert into date_time values("10000-10-10 00:00:00");
   ERROR 1292 (22007): Incorrect datetime value: '10000-10-10 00:00:00' for column 'time' at row 1 # 報錯
   

3. 輸入”23-01-02 12:23:56"測試

   > insert into date_time values("23-01-02 12:23:56");
   > insert into date_time values("79-01-02 12:23:56");
   > select * from date_time;
   +---------------------+
   | time                |
   +---------------------+
   | 2023-01-02 12:23:56 |
   | 1979-01-02 12:23:56 |
   +---------------------+
   

   會和date一樣，'00'-'69'會轉換為2000-2069，'70'-'99'會轉換為1970-1999

4. 測試年份輸入三位或者一位

   > insert into date_time values("179-01-02 12:23:56");
   > insert into date_time values("9-01-02 12:23:56");
   > select * from date_time;
   +---------------------+
   | time                |
   +---------------------+
   | 2023-01-02 12:23:56 |
   | 1979-01-02 12:23:56 |
   | 0179-01-02 12:23:56 |
   | 0009-01-02 12:23:56 |
   +---------------------+
   

   可以存儲進去，但會自動在前面補足0，使年份變為4位

5. 輸入年份格式為”00YY“

   > insert into date_time values("0079-01-02 12:23:56");
   > select * from date_time;
   +---------------------+
   | time                |
   +---------------------+
   | 2023-01-02 12:23:56 |
   | 1979-01-02 12:23:56 |
   | 0179-01-02 12:23:56 |
   | 0009-01-02 12:23:56 |
   | 0079-01-02 12:23:56 |   # 可以存儲
   +---------------------+
   

6. 最后測試極限時間

   > insert into date_time values("0000-00-00 00:00:00");
   > insert into date_time values("9999-12-31 23:59:59");
   > select * from date_time;
   +---------------------+
   | time                |
   +---------------------+
   | 2023-01-02 12:23:56 |
   | 1979-01-02 12:23:56 |
   | 0179-01-02 12:23:56 |
   | 0009-01-02 12:23:56 |
   | 0079-01-02 12:23:56 |
   | 0000-00-00 00:00:00 |
   | 9999-12-31 23:59:59 |
   +---------------------+
   

總結：

1. datetime類型范圍為”0000-00-00 00:00:00“~”9999-12-31 23:59:59“；
2. 要存儲年份為兩位數的需要在前面補足”00“，不然會按照date類型進行轉換（'00'-'69'會轉換為2000-2069，'70'-'99'會轉換為1970-1999）；