fix table modify database syntax (apache#722)

Author: leto-bbq

src/UserGuide/Master/Table/Basic-Concept/Database-Management.md

@@ -154,7 +154,7 @@ Used to modify some attributes in the database.
 **Syntax:**
 
 ```SQL
-ALTER DATABASE (IF EXISTS)? databaseName=qualifiedName (WITH properties)?
+ALTER DATABASE (IF EXISTS)? database=identifier SET PROPERTIES propertyAssignments
 ```
 
 **Note:**
@@ -164,7 +164,7 @@ ALTER DATABASE (IF EXISTS)? databaseName=qualifiedName (WITH properties)?
 **Example:**
 
 ```SQL
-ALTER TABLE database1 with(TTL=31536000000);
+ALTER DATABASE database1 SET PROPERTIES TTL=31536000000;
 ```
 
 ### 1.6 Delete a Database

src/UserGuide/latest-Table/Basic-Concept/Database-Management.md

@@ -154,7 +154,7 @@ Used to modify some attributes in the database.
 **Syntax:**
 
 ```SQL
-ALTER DATABASE (IF EXISTS)? databaseName=qualifiedName (WITH properties)?
+ALTER DATABASE (IF EXISTS)? database=identifier SET PROPERTIES propertyAssignments
 ```
 
 **Note:**
@@ -164,7 +164,7 @@ ALTER DATABASE (IF EXISTS)? databaseName=qualifiedName (WITH properties)?
 **Example:**
 
 ```SQL
-ALTER TABLE database1 with(TTL=31536000000);
+ALTER DATABASE database1 SET PROPERTIES TTL=31536000000;
 ```
 
 ### 1.6 Delete a Database

src/zh/UserGuide/Master/Table/Basic-Concept/Database-Management.md

@@ -156,7 +156,7 @@ IoTDB> show databases details
 **语法：**
 
 ```SQL
-ALTER DATABASE (IF EXISTS)? databaseName=qualifiedName (WITH properties)?
+ALTER DATABASE (IF EXISTS)? database=identifier SET PROPERTIES propertyAssignments
 ```
 
 **说明：**
@@ -166,7 +166,7 @@ ALTER DATABASE (IF EXISTS)? databaseName=qualifiedName (WITH properties)?
 **示例:** 
 
 ```SQL
-ALTER TABLE database1 with(TTL=31536000000);
+ALTER DATABASE database1 SET PROPERTIES TTL=31536000000;
 ```
 
 ### 1.6 删除数据库

src/zh/UserGuide/latest-Table/Basic-Concept/Database-Management.md

@@ -156,7 +156,7 @@ IoTDB> show databases details
 **语法：**
 
 ```SQL
-ALTER DATABASE (IF EXISTS)? databaseName=qualifiedName (WITH properties)?
+ALTER DATABASE (IF EXISTS)? database=identifier SET PROPERTIES propertyAssignments
 ```
 
 **说明：**
@@ -166,7 +166,7 @@ ALTER DATABASE (IF EXISTS)? databaseName=qualifiedName (WITH properties)?
 **示例:** 
 
 ```SQL
-ALTER TABLE database1 with(TTL=31536000000);
+ALTER DATABASE database1 SET PROPERTIES TTL=31536000000;
 ```
 
 ### 1.6 删除数据库