UPDATE · k8s原理与实践

[TOC] # UPDATE ## 描述该语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]…] ~~~ ## 参数解释 <table data-tag="table" id="table-af1-lpd-5dp" class="table"><colgroup width="198" span="1" data-tag="col" id="col-du8-tad-5h0" colwidth="1*" colnum="1" colname="col1" style="width:50%" class="col"></colgroup><colgroup width="456" span="1" data-tag="col" id="col-jqe-sp8-279" colwidth="1*" colnum="2" colname="col2" style="width:50%" class="col"></colgroup><thead id="thead-69x-osd-h31" class="thead"><tr id="tr-1nz-zf2-2mk"><th id="td-km4-dyo-e9u">参数</th><th id="td-bds-jd4-olv">描述</th></tr></thead><tbody data-tag="tbody" id="tbody-xxh-7mo-65t" class="tbody"><tr data-tag="tr" id="tr-vse-cy4-7m4" class="tr"><td data-tag="td" id="td-ws7-26q-d8s" class="td">IGNORE</td><td data-tag="td" id="td-pw9-44m-pmt" class="td">在 INSERT 语句执行过程中发生的错误将会被忽略。</td></tr><tr data-tag="tr" id="tr-ay5-b94-lmw" class="tr"><td data-tag="td" id="td-d4f-kjm-2s7" class="td">table_references</td><td data-tag="td" id="td-zrv-16z-5k6" class="td">指定修改表名，多表修改时，表名直接‘，’作为间隔。</td></tr><tr data-tag="tr" id="tr-9ho-h03-b3t" class="tr"><td data-tag="td" id="td-1e1-r7p-zls" class="td">where_condition</td><td data-tag="td" id="td-2pl-yfg-nq0" class="td">指定过滤条件。</td></tr><tr data-tag="tr" id="tr-r05-d53-zpr" class="tr"><td data-tag="td" id="td-t8l-pv5-fs4" class="td">row_count</td><td data-tag="td" id="td-zh7-dq3-ngt" class="td">限制的行数。</td></tr><tr data-tag="tr" id="tr-26u-xzt-wbv" class="tr"><td data-tag="td" id="td-0ty-lxm-v8q" class="td">tbl_name</td><td data-tag="td" id="td-okr-n0x-6pm" class="td">插入表名。</td></tr><tr data-tag="tr" id="tr-gfu-mfg-wfe" class="tr"><td data-tag="td" id="td-ptj-ypf-rty" class="td">partition_name</td><td data-tag="td" id="td-ayu-t94-45y" class="td">插入表指定的分区名。</td></tr><tr data-tag="tr" id="tr-d51-6bm-t8v" class="tr"><td data-tag="td" id="td-ynr-59k-f3p" class="td">column_name</td><td data-tag="td" id="td-b2r-o63-df8" class="td">列名。</td></tr><tr data-tag="tr" id="tr-v24-7xz-oin" class="tr"><td data-tag="td" id="td-yj7-zuo-sbu" class="td">column_name ASC</td><td data-tag="td" id="td-1ce-5uc-gu4" class="td">按列名升序修改。</td></tr><tr data-tag="tr" id="tr-x46-whw-g3t" class="tr"><td data-tag="td" id="td-34t-zwh-2ow" class="td">column_name DESC</td><td data-tag="td" id="td-ygd-wi9-etu" class="td">按列名降序修改。</td></tr></tbody></table> ## 注意事项不管是多表还是单表更新都不支持直接对子查询进行更新值操作，例如：`update (select * from t1) set c1 = 100;` ## 示例 1. 创建示例表 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. 将表 t1 中 "t1.c1=1" 对应的那一行数据的 c2 列值修改为 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. 将表 t1 中按照 c2 列排序的前两行数据的 c2 列值修改为 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. 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。 ~~~ 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。 ~~~ 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. 修改多个表。修改 t1 表和 t2 表的p2分区中满足 "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。 ~~~ 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. 对可更新视图 v 进行更新值。 ~~~ 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) ~~~