OceanBase UPDATE

描述

該語句用于修改表中的字段值。

格式

UPDATE [IGNORE] table_references
    SET update_asgn_list
    [WHERE where_condition] 
    [ORDER BY order_list]
    [LIMIT row_count];

table_references:
    tbl_name [PARTITION (partition_name,...)] [, ...]

update_asgn_list:
    column_name = expr [, ...]

order_list: 
    column_name [ASC|DESC] [, column_name [ASC|DESC]…]

參數(shù)解釋

注意事項(xiàng)

不管是多表還是單表更新都不支持直接對(duì)子查詢進(jìn)行更新值操作，例如：?update (select * from t1) set c1 = 100;?

示例

1. 創(chuàng)建示例表 t1 和 t2。

OceanBase(admin@test)>create table t1(c1 int primary key, c2 int);
Query OK, 0 rows affected (0.16 sec)
OceanBase(admin@test)>select * from t1;
+----+------+
| c1 | c2   |
+----+------+
|  1 |    1 |
|  2 |    2 |
|  3 |    3 |
|  4 |    4 |
+----+------+
4 rows in set (0.06 sec)

OceanBase(admin@test)>create table t2(c1 int primary key, c2 int) partition by key(c1) partitions 4;
Query OK, 0 rows affected (0.19 sec)
OceanBase(admin@test)>select * from t2;
+----+------+
| c1 | c2   |
+----+------+
|  5 |    5 |
|  1 |    1 |
|  2 |    2 |
|  3 |    3 |
+----+------+
4 rows in set (0.02 sec)

2. 將表 t1 中 "t1.c1=1" 對(duì)應(yīng)的那一行數(shù)據(jù)的 c2 列值修改為 100。

OceanBase(admin@test)>update t1 set t1.c2 = 100 where t1.c1 = 1;
Query OK, 1 row affected (0.02 sec)
Rows matched: 1  Changed: 1  Warnings: 0

OceanBase(admin@test)>select * from t1;
+----+------+
| c1 | c2   |
+----+------+
|  1 |  100 |
|  2 |    2 |
|  3 |    3 |
|  4 |    4 |
+----+------+
4 rows in set (0.01 sec)

3. 將表 t1 中按照 c2 列排序的前兩行數(shù)據(jù)的 c2 列值修改為 100。

OceanBase(admin@test)>update t1 set t1.c2 = 100 order by c2 limit 2;
Query OK, 2 rows affected (0.02 sec)
Rows matched: 2  Changed: 2  Warnings: 0

OceanBase(admin@test)>select * from t1;
+----+------+
| c1 | c2   |
+----+------+
|  1 |  100 |
|  2 |  100 |
|  3 |    3 |
|  4 |    4 |
+----+------+
4 rows in set (0.01 sec)

4. 將表 t2 中 p2 分區(qū)的數(shù)據(jù)中 "t2.c1 > 2" 的對(duì)應(yīng)行數(shù)據(jù)的 c2 列值修改為 100。

OceanBase(admin@test)>update t2 partition(p2) set t2.c2 = 100 where t2.c1 > 2;
Query OK, 1 row affected (0.02 sec)
Rows matched: 1  Changed: 1  Warnings: 0

OceanBase(admin@test)>select * from t2;
+----+------+
| c1 | c2   |
+----+------+
|  5 |    5 |
|  1 |    1 |
|  2 |    2 |
|  3 |  100 |
+----+------+
4 rows in set (0.06 sec)

5. 修改多個(gè)表。將 t1 表和 t2 表中滿足 "t1.c1 = t2.c1" 對(duì)應(yīng)行的數(shù)據(jù) t1 表中的 c2 列值修改為 100，t2 表中的 c2 列值修改為 200。

OceanBase(admin@test)>update t1,t2 set t1.c2 = 100, t2.c2 = 200 where t1.c2 = t2.c2;
Query OK, 6 rows affected (0.03 sec)
Rows matched: 6  Changed: 6  Warnings: 0

OceanBase(admin@test)>select * from t1;
+----+------+
| c1 | c2   |
+----+------+
|  1 |  100 |
|  2 |  100 |
|  3 |  100 |
|  4 |    4 |
+----+------+
4 rows in set (0.00 sec)

OceanBase(admin@test)>select * from t2;
+----+------+
| c1 | c2   |
+----+------+
|  5 |    5 |
|  1 |  200 |
|  2 |  200 |
|  3 |  200 |
+----+------+
4 rows in set (0.01 sec)

6. 修改多個(gè)表。修改 t1 表和 t2 表的p2分區(qū)中滿足 "t1.c1 = t2.c1" 對(duì)應(yīng)行的數(shù)據(jù) t1 表中的 c2 列值修改為 100，t2 表中的 c2 列值修改為 200。

OceanBase(admin@test)>update t1,t2 partition(p2) set t1.c2 = 100, t2.c2 = 200 where t1.c2 = t2.c2;
Query OK, 6 rows affected (0.02 sec)
Rows matched: 6  Changed: 6  Warnings: 0

OceanBase(admin@test)>select * from t1;
+----+------+
| c1 | c2   |
+----+------+
|  1 |  100 |
|  2 |  100 |
|  3 |  100 |
|  4 |    4 |
+----+------+
4 rows in set (0.01 sec)

OceanBase(admin@test)>select * from t2;
+----+------+
| c1 | c2   |
+----+------+
|  5 |    5 |
|  1 |  200 |
|  2 |  200 |
|  3 |  200 |
+----+------+
4 rows in set (0.01 sec)

7. 對(duì)可更新視圖 v 進(jìn)行更新值。

OceanBase(admin@test)>create view v as select * from t1;
Query OK, 0 rows affected (0.07 sec)

OceanBase(admin@test)>update v set v.c2 = 100 where v.c1 = 1;
Query OK, 1 row affected (0.02 sec)
Rows matched: 1  Changed: 1  Warnings: 0

OceanBase(admin@test)>select * from v;
+----+------+
| c1 | c2   |
+----+------+
|  1 |  100 |
|  2 |    2 |
|  3 |    3 |
|  4 |    4 |
+----+------+
4 rows in set (0.01 sec)