add pid; ensure node id if no

data/1.OceanBase初阶/2.基本操作/7.查询数据/children.json

+{
+  "type": "code_options",
+  "author": "刘鑫",
+  "source": "children.md"
+}
\ No newline at end of file

data/1.OceanBase初阶/2.基本操作/7.查询数据/children.md

+# 查找子节点
+
+有一个表 node，有两列
+
+```shell
+# select item from node;
+id  | pid
+------------------
+1   | 0
+2   | 1
+3   | 1
+4   | 3
+5   | 2
+...   
+```
+
+其中id是自增主键，pid指向父节点的id。那么给定某一个id ，查找它的子节点的查询应该是：
+
+## 答案
+
+```sql
+select * from node where pid = ?
+```
+
+## 选项
+
+### 缺少 where
+
+```sql
+select * from node pid = ?
+```
+
+### 结构错误
+
+```sql
+from node select * where pid = ?
+```
+
+### select 不完整
+
+```sql
+select from node where pid = ?
+```

data/1.OceanBase初阶/2.基本操作/7.查询数据/config.json

@@ -3,6 +3,7 @@
   "node_id": "oceanbase-6f727423ee414b85b6ed90bebcdd88b8",
   "title": "查询数据",
   "export": [
-    "hello.json"
+    "hello.json",
+    "children.json"
   ]
 }
\ No newline at end of file

data/2.OceanBase中阶/3.表查询/config.json

 {
   "keywords": [],
   "node_id": "oceanbase-641f612acf59456187b9573a4398e20b",
-  "title": "表查询"
+  "title": "表查询",
+  "export": []
 }
\ No newline at end of file

data/3.OceanBase高阶/3.编程和查询/2.连接查询/config.json

 {
   "keywords": [],
   "node_id": "oceanbase-d28015752f834bffacc6dfb9ab64b8c2",
-  "title": "连接查询"
+  "title": "连接查询",
+  "export": []
 }
\ No newline at end of file

src/tree.py

+import logging
 from genericpath import exists
 import json
 import os
@@ -7,6 +8,9 @@ import re
 
 id_set = set()
 
+logger = logging.getLogger(__name__)
+
+
 def load_json(p):
     with open(p, 'r') as f:
         return json.loads(f.read())
@@ -18,13 +22,22 @@ def dump_json(p, j, exist_ok=False, override=False):
             if not override:
                 return
         else:
-            print(f"{p} already exist")
+            logger.error(f"{p} already exist")
             sys.exit(0)
 
     with open(p, 'w+') as f:
         f.write(json.dumps(j, indent=2, ensure_ascii=False))
 
 
+def ensure_config(path):
+    config_path = os.path.join(path, "config.json")
+    if not os.path.exists(config_path):
+        node = {"keywords": []}
+        dump_json(config_path, node, exist_ok=True, override=False)
+        return node
+    else:
+        return load_json(config_path)
+
 def parse_no_name(d):
     p = r'(\d+)\.(.*)'
     m = re.search(p, d)
@@ -37,6 +50,7 @@ def parse_no_name(d):
 
     return no, dir_name
 
+
 def check_export(base, cfg):
     flag = False
     exports = []
@@ -114,8 +128,8 @@ def gen_tree(data_path):
         return node, node_children
 
     # 根节点
+    cfg = ensure_config(data_path)
     cfg_path = os.path.join(data_path, 'config.json')
-    cfg = load_json(cfg_path)
     if ensure_node_id(cfg):
         dump_json(cfg_path, cfg, exist_ok=True, override=True)
 
@@ -134,7 +148,7 @@ def gen_tree(data_path):
         print(level_no_dir)
         no, level_name = parse_no_name(level_no_name)
         level_path = os.path.join(level_no_dir, 'config.json')
-        level_cfg = load_json(level_path)
+        level_cfg = ensure_config(level_no_dir)
         if ensure_node_id(level_cfg) or check_export(level_no_dir, level_cfg):
             dump_json(level_path, level_cfg, exist_ok=True, override=True)
         if ensure_title(level_cfg, level_path):
@@ -148,7 +162,7 @@ def gen_tree(data_path):
         for chapter_no_dir, chapter_no_name in list_dir(level_no_dir):
             no, chapter_name = parse_no_name(chapter_no_name)
             chapter_path = os.path.join(chapter_no_dir, 'config.json')
-            chapter_cfg = load_json(chapter_path)
+            chapter_cfg = ensure_config(chapter_no_dir)
             if ensure_node_id(chapter_cfg) or check_export(chapter_no_dir, chapter_cfg):
                 dump_json(chapter_path, chapter_cfg, exist_ok=True, override=True)
             if ensure_title(chapter_cfg, chapter_path):
@@ -162,7 +176,7 @@ def gen_tree(data_path):
             for section_no_dir, section_no_name in list_dir(chapter_no_dir):
                 no, section_name = parse_no_name(section_no_name)
                 sec_path = os.path.join(section_no_dir, 'config.json')
-                sec_cfg = load_json(sec_path)
+                sec_cfg = ensure_config(section_no_dir)
                 flag = ensure_node_id(sec_cfg) or check_export(section_no_dir, sec_cfg)
 
                 section_node, section_node_children = make_node(