使用 UPDATE 语句修改表中的字段值。

    示例如下：

    创建示例表 t1 和 t2。

    1. obclient> CREATE TABLE t1(c1 int primary key, c2 int);
    2. Query OK, 0 rows affected (0.16 sec)
    3. obclient> SELECT * FROM t1;
    4. +----+------+
    5. | c1 | c2   |
    6. +----+------+
    7. |  1 |    1 |
    8. |  2 |    2 |
    9. |  3 |    3 |
    10. |  4 |    4 |
    11. +----+------+
    12. 4 rows in set (0.06 sec)
    14. obclient> CREATE TABLE t2(c1 int primary key, c2 int) partition by key(c1) partitions 4;
    15. Query OK, 0 rows affected (0.19 sec)
    16. obclient> SELECT * FROM t2;
    17. +----+------+
    18. | c1 | c2   |
    19. +----+------+
    20. |  5 |    5 |
    21. |  1 |    1 |
    22. |  2 |    2 |
    23. |  3 |    3 |
    24. +----+------+
    25. 4 rows in set (0.02 sec)

    • 将表 t1 中 “t1.c1=1” 对应的那一行数据的 c2 列值修改为 100。

      1. obclient> UPDATE t1 SET t1.c2 = 100 WHERE t1.c1 = 1;
      2. Query OK, 1 row affected (0.02 sec)
      3. Rows matched: 1  Changed: 1  Warnings: 0
      5. obclient> SELECT * FROM t1;
      6. +----+------+
      7. | c1 | c2   |
      8. +----+------+
      9. |  1 |  100 |
      10. |  2 |    2 |
      11. |  3 |    3 |
      12. |  4 |    4 |
      13. +----+------+
      14. 4 rows in set (0.01 sec)

    • 将表 t1 中按照 c2 列排序的前两行数据的 c2 列值修改为 100。

      1. obclient> UPDATE t1 set t1.c2 = 100 ORDER BY c2 LIMIT 2;
      2. Query OK, 2 rows affected (0.02 sec)
      3. Rows matched: 2  Changed: 2  Warnings: 0
      5. obclient> SELECT * FROM t1;
      6. +----+------+
      7. | c1 | c2   |
      8. +----+------+
      9. |  1 |  100 |
      10. |  2 |  100 |
      11. |  3 |    3 |
      12. |  4 |    4 |
      13. +----+------+
      14. 4 rows in set (0.01 sec)

    • 将表 t2 中 p2 分区的数据中”t2.c1 > 2” 的对应行数据的 c2 列值修改为 100。

      1. obclient> UPDATE t2 partition(p2) SET t2.c2 = 100 WHERE t2.c1 > 2;
      2. Query OK, 1 row affected (0.02 sec)
      3. Rows matched: 1  Changed: 1  Warnings: 0
      5. obclient> SELECT * FROM t2;
      6. +----+------+
      7. | c1 | c2   |
      8. +----+------+
      9. |  5 |    5 |
      10. |  1 |    1 |
      11. |  2 |    2 |
      12. |  3 |  100 |
      13. +----+------+
      14. 4 rows in set (0.06 sec)

    • 修改多个表。将 t1 表和 t2 表中满足 “t1.c1 = t2.c1” 对应行的数据 t1 表中的 c2 列值修改为 100，t2 表中的 c2 列值修改为 200。

      1. obclient> UPDATE t1,t2 SET t1.c2 = 100, t2.c2 = 200 WHERE t1.c2 = t2.c2;
      2. Query OK, 6 rows affected (0.03 sec)
      3. Rows matched: 6  Changed: 6  Warnings: 0
      5. obclient> SELECT * FROM t1;
      6. +----+------+
      7. | c1 | c2   |
      8. +----+------+
      9. |  1 |  100 |
      10. |  2 |  100 |
      11. |  3 |  100 |
      12. |  4 |    4 |
      13. +----+------+
      14. 4 rows in set (0.00 sec)
      16. obclient> SELECT * FROM t2;
      17. +----+------+
      18. | c1 | c2   |
      19. +----+------+
      20. |  5 |    5 |
      21. |  1 |  200 |
      22. |  2 |  200 |
      23. |  3 |  200 |
      24. +----+------+
      25. 4 rows in set (0.01 sec)

    更多 UPDATE 语句相关的语法请参见 UPDATE。