sql: RENAME TABLE supports renaming multiple tables and across dbs

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

@@ -6,7 +6,7 @@ aliases: ['/docs-cn/dev/sql-statements/sql-statement-rename-table/','/docs-cn/de
 
 # 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，支持同时重命名多个表及跨数据库重命名。
 
 ## 语法图
 
@@ -20,8 +20,6 @@ TableToTable ::=
 
 ## 示例
 
-{{< copyable "sql" >}}
-
 ```sql
 CREATE TABLE t1 (a int);
 ```
@@ -30,8 +28,6 @@ CREATE TABLE t1 (a int);
 Query OK, 0 rows affected (0.12 sec)
 ```
 
-{{< copyable "sql" >}}
-
 ```sql
 SHOW TABLES;
 ```
@@ -42,11 +38,9 @@ SHOW TABLES;
 +----------------+
 | t1             |
 +----------------+
-1 row in set (0.00 sec)
+1 row in set (0.00 sec)77
 ```
 
-{{< copyable "sql" >}}
-
 ```sql
 RENAME TABLE t1 TO t2;
 ```
@@ -55,8 +49,6 @@ RENAME TABLE t1 TO t2;
 Query OK, 0 rows affected (0.08 sec)
 ```
 
-{{< copyable "sql" >}}
-
 ```sql
 SHOW TABLES;
 ```
@@ -70,6 +62,62 @@ 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：
+
+```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)
+```
+
 ## 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)。