Tambah dan kurangi nilai baris sebesar 1 di MySQL

Dua kueri untuk menambah/mengurangi nilai bidang tidak diperlukan:

mysql_query("UPDATE table SET field = field + 1 WHERE id = $number");

adalah kueri yang benar-benar valid seperti yang Anda lihat selanjutnya:

mysql> describe points;
+--------+---------+------+-----+---------+-------+
| Field  | Type    | Null | Key | Default | Extra |
+--------+---------+------+-----+---------+-------+
| uid    | int(11) | NO   | PRI | NULL    |       |
| points | int(11) | YES  |     | 0       |       |
+--------+---------+------+-----+---------+-------+
2 rows in set (0.05 sec)

mysql> insert into points VALUES (1,0),(2,0);
Query OK, 2 rows affected (0.14 sec)

mysql> select * from points;
+-----+--------+
| uid | points |
+-----+--------+
|   1 |      0 |
|   2 |      0 |
+-----+--------+
2 rows in set (0.05 sec)

mysql> update points set points = points+1 where uid = 1;
Query OK, 1 row affected (0.27 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select * from points;
+-----+--------+
| uid | points |
+-----+--------+
|   1 |      1 |
|   2 |      0 |
+-----+--------+
2 rows in set (0.00 sec)

Setelah itu diuji, apakah Anda yakin Anda masuk ke if (loggedin()) klausa?

Saya harus setuju dengan KM , akan menyenangkan untuk melihat output dari echo $query1; atau echo $query2;