add cassandra in readme

README.md

@@ -22,17 +22,18 @@
 功能清单
 ====
 
-| 数据库 | 查询 | 审核 | 执行 | 备份 | 数据字典 | 慢日志 | 会话管理 | 账号管理 | 参数管理 | 数据归档 |
-| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
-| MySQL | √ | √ | √ | √ | √ | √ | √ | √ | √ | √ |
-| MsSQL | √ | × | √ | × | √ | × | × | × | × | × |
-| Redis | √ | × | √ | × | × | × | × | × | × | × |
-| PgSQL | √ | × | √ | × | × | × | × | × | × | × |
-| Oracle | √ | √ | √ | √ | √ | × | √ | × | × | × |
-| MongoDB | √ | √ | √ | × | × | × | √ | √ | × | × |
-| Phoenix | √ | × | √ | × | × | × | × | × | × | × |
-| ODPS | √ | × | × | × | × | × | × | × | × | × |
+| 数据库  | 查询 | 审核 | 执行 | 备份 | 数据字典 | 慢日志 | 会话管理 | 账号管理 | 参数管理 | 数据归档 |
+|------------| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
+| MySQL  | √ | √ | √ | √ | √ | √ | √ | √ | √ | √ |
+| MsSQL  | √ | × | √ | × | √ | × | × | × | × | × |
+| Redis  | √ | × | √ | × | × | × | × | × | × | × |
+| PgSQL  | √ | × | √ | × | × | × | × | × | × | × |
+| Oracle  | √ | √ | √ | √ | √ | × | √ | × | × | × |
+| MongoDB  | √ | √ | √ | × | × | × | √ | √ | × | × |
+| Phoenix  | √ | × | √ | × | × | × | × | × | × | × |
+| ODPS  | √ | × | × | × | × | × | × | × | × | × |
 | ClickHouse | √ | √ | √ | × | × | × | × | × | × | × |
+| Cassandra | √ | × | √ | × | × | × | × | × | × | × |