Bisakah saya membandingkan stempel waktu MysQL dengan kolom datetime? Apa itu buruk?

Ya, Anda dapat membandingkan datetime dengan timestamp . Ini tidak buruk, tetapi perhatikan hal-hal berikut:

Dari Panduan Referensi MySQL ::Jenis DATETIME, DATE, dan TIMESTAMP .

Perhatikan bagaimana kasus uji berikut berfungsi dengan baik:

CREATE TABLE t1 (d1 datetime, d2 timestamp);

INSERT INTO t1 VALUES ('1968-01-01 00:00:00', '1980-01-01 00:00:00');
INSERT INTO t1 VALUES ('2040-01-01 00:00:00', '1980-01-01 00:00:00');

SELECT * FROM t1 WHERE d2 < d1;
+---------------------+---------------------+
| d1                  | d2                  |
+---------------------+---------------------+
| 2040-01-01 00:00:00 | 1980-01-01 00:00:00 |
+---------------------+---------------------+
1 row in set (0.00 sec)

SELECT * FROM t1 WHERE d2 > d1;
+---------------------+---------------------+
| d1                  | d2                  |
+---------------------+---------------------+
| 1968-01-01 00:00:00 | 1980-01-01 00:00:00 |
+---------------------+---------------------+
1 row in set (0.00 sec)

SELECT * FROM t1 WHERE d2 < '2040-01-01 00:00:00';
+---------------------+---------------------+
| d1                  | d2                  |
+---------------------+---------------------+
| 1968-01-01 00:00:00 | 1980-01-01 00:00:00 |
| 2040-01-01 00:00:00 | 1980-01-01 00:00:00 |
+---------------------+---------------------+
2 rows in set (0.00 sec)

SELECT * FROM t1 WHERE d2 > '2040-01-01 00:00:00';
Empty set (0.00 sec)