修复高斯数据库生成错误.

https://github.com/baomidou/generator/issues/11

mybatis-plus-generator/src/main/java/com/baomidou/mybatisplus/generator/config/querys/GaussQuery.java

@@ -25,8 +25,8 @@ public class GaussQuery extends AbstractDbQuery {
 
     @Override
     public String tablesSql() {
-        return "SELECT DISTINCT T1.TABLE_NAME,T2.COMMENTS AS TABLE_COMMENT FROM USER_TAB_COLUMNS T1 " +
-            "LEFT JOIN USER_TAB_COMMENTS T2 ON T1.TABLE_NAME = T2.TABLE_NAME WHERE 1=1 ";
+        return "SELECT * FROM (SELECT DISTINCT T1.TABLE_NAME,T2.COMMENTS AS TABLE_COMMENT FROM USER_TAB_COLUMNS T1 " +
+            "LEFT JOIN USER_TAB_COMMENTS T2 ON T1.TABLE_NAME = T2.TABLE_NAME ) a WHERE 1=1 ";
     }
 
     @Override