sql: RENAME TABLE supports renaming multiple tables and across dbs (#…

…19452) (#19457)

sql-statements/sql-statement-rename-table.md

@@ -5,7 +5,7 @@ summary: TiDB 数据库中 RENAME TABLE 的使用概况。
 
 # RENAME TABLE
 
-`RENAME TABLE` 语句用于对已有表进行重命名。
+`RENAME TABLE` 语句用于重命名现有表和视图，支持同时重命名多个表及跨数据库重命名。
 
 ## 语法图
 
@@ -19,8 +19,6 @@ TableToTable ::=
 
 ## 示例
 
-{{< copyable "sql" >}}
-
 ```sql
 CREATE TABLE t1 (a int);
 ```
@@ -29,8 +27,6 @@ CREATE TABLE t1 (a int);
 Query OK, 0 rows affected (0.12 sec)
 ```
 
-{{< copyable "sql" >}}
-
 ```sql
 SHOW TABLES;
 ```
@@ -44,8 +40,6 @@ SHOW TABLES;
 1 row in set (0.00 sec)
 ```
 
-{{< copyable "sql" >}}
-
 ```sql
 RENAME TABLE t1 TO t2;
 ```
@@ -54,8 +48,6 @@ RENAME TABLE t1 TO t2;
 Query OK, 0 rows affected (0.08 sec)
 ```
 
-{{< copyable "sql" >}}
-
 ```sql
 SHOW TABLES;
 ```
@@ -69,6 +61,103 @@ SHOW TABLES;
 1 row in set (0.00 sec)
 ```
 
+以下示例演示了如何跨数据库重命名多个表（假设数据库 `db1`、`db2`、`db3` 和 `db4` 已存在，表 `db1.t1` 和 `db3.t3` 已存在）：
+
+```sql
+RENAME TABLE db1.t1 To db2.t2, db3.t3 To db4.t4;
+```
+
+```
+Query OK, 0 rows affected (0.08 sec)
+```
+
+```sql
+USE db1; SHOW TABLES;
+```
+
+```
+Database changed
+Empty set (0.00 sec)
+```
+
+```sql
+USE db2; SHOW TABLES;
+```
+
+```
+Database changed
++---------------+
+| Tables_in_db2 |
++---------------+
+| t2            |
++---------------+
+1 row in set (0.00 sec)
+```
+
+```sql
+USE db3; SHOW TABLES;
+```
+
+```
+Database changed
+Empty set (0.00 sec)
+```
+
+```sql
+USE db4; SHOW TABLES;
+```
+
+```
+Database changed
++---------------+
+| Tables_in_db4 |
++---------------+
+| t4            |
++---------------+
+1 row in set (0.00 sec)
+```
+
+原子重命名可以确保在交换表时，表始终存在。
+
+```sql
+CREATE TABLE t1(id int PRIMARY KEY);
+```
+
+```
+Query OK, 0 rows affected (0.04 sec)
+```
+
+```sql
+CREATE TABLE t1_new(id int PRIMARY KEY, n CHAR(0));
+````
+
+```
+Query OK, 0 rows affected (0.04 sec)
+```
+
+```sql
+RENAME TABLE t1 TO t1_old, t1_new TO t1;
+```
+
+```
+Query OK, 0 rows affected (0.07 sec)
+```
+
+```sql
+SHOW CREATE TABLE t1\G
+```
+
+```
+*************************** 1. row ***************************
+       Table: t1
+Create Table: CREATE TABLE `t1` (
+  `id` int NOT NULL,
+  `n` char(0) DEFAULT NULL,
+  PRIMARY KEY (`id`) /*T![clustered_index] CLUSTERED */
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin
+1 row in set (0.00 sec)
+```
+
 ## MySQL 兼容性
 
 `RENAME TABLE` 语句与 MySQL 完全兼容。如发现任何兼容性差异，请尝试 [TiDB 支持资源](/support.md)。