diff --git "a/data/1.PostgreSQL\345\210\235\351\230\266/3.\346\237\245\350\257\242\346\225\260\346\215\256/4.\345\270\270\350\247\201\346\225\260\346\215\256\347\261\273\345\236\213/datetime.json" "b/data/1.PostgreSQL\345\210\235\351\230\266/3.\346\237\245\350\257\242\346\225\260\346\215\256/4.\345\270\270\350\247\201\346\225\260\346\215\256\347\261\273\345\236\213/datetime.json"
new file mode 100644
index 0000000000000000000000000000000000000000..ce14a1923a0818b3654d858fa08f86127fec1a7f
--- /dev/null
+++ "b/data/1.PostgreSQL\345\210\235\351\230\266/3.\346\237\245\350\257\242\346\225\260\346\215\256/4.\345\270\270\350\247\201\346\225\260\346\215\256\347\261\273\345\236\213/datetime.json"
@@ -0,0 +1,7 @@
+{
+  "type": "code_options",
+  "author": "ccat",
+  "source": "datetime.md",
+  "notebook_enable": false,
+  "exercise_id": "89e67a85e4144bea88aded6e4dd280c2"
+}
\ No newline at end of file
diff --git "a/data/1.PostgreSQL\345\210\235\351\230\266/3.\346\237\245\350\257\242\346\225\260\346\215\256/4.\345\270\270\350\247\201\346\225\260\346\215\256\347\261\273\345\236\213/datetime.md" "b/data/1.PostgreSQL\345\210\235\351\230\266/3.\346\237\245\350\257\242\346\225\260\346\215\256/4.\345\270\270\350\247\201\346\225\260\346\215\256\347\261\273\345\236\213/datetime.md"
new file mode 100644
index 0000000000000000000000000000000000000000..4152a515bf54e6c0c27869954b089855253de5fb
--- /dev/null
+++ "b/data/1.PostgreSQL\345\210\235\351\230\266/3.\346\237\245\350\257\242\346\225\260\346\215\256/4.\345\270\270\350\247\201\346\225\260\346\215\256\347\261\273\345\236\213/datetime.md"
@@ -0,0 +1,82 @@
+# 时间默认值
+
+Joe 写了一个订单表的创建语句：
+
+```postgresql
+create table orders (
+    id serial primary key,
+    item_id int,
+    amount int,
+    unit_price money,
+    price money
+);
+```
+
+现在，Joe 需要给这个表加入下单时间，即订单写入数据库的时间，那么他应该将这个语句修改为：
+
+## 答案
+
+```postgresql
+create table orders (
+    id serial primary key,
+    item_id int,
+    amount int,
+    unit_price money,
+    price money,
+    ts timestamp default now()
+);
+```
+
+## 选项
+
+### A
+
+```postgresql
+create table orders (
+    id serial primary key,
+    item_id int,
+    amount int,
+    unit_price money,
+    price money,
+    ts varchar(16) default now()
+);
+```
+
+### B
+
+```postgresql
+create table orders (
+    id serial primary key,
+    item_id int,
+    amount int,
+    unit_price money,
+    price money,
+    ts varchar(16) format 'yyyy-mm-dd'
+);
+```
+
+### C
+
+```postgresql
+create table orders (
+    id serial primary key,
+    item_id int,
+    amount int,
+    unit_price money,
+    price money,
+    ts date default now()
+);
+```
+
+### D
+
+```postgresql
+create table orders (
+    id serial primary key,
+    item_id int,
+    amount int,
+    unit_price money,
+    price money,
+    ts datetime default now()
+);
+```
diff --git "a/data/1.PostgreSQL\345\210\235\351\230\266/3.\346\237\245\350\257\242\346\225\260\346\215\256/4.\345\270\270\350\247\201\346\225\260\346\215\256\347\261\273\345\236\213/description.json" "b/data/1.PostgreSQL\345\210\235\351\230\266/3.\346\237\245\350\257\242\346\225\260\346\215\256/4.\345\270\270\350\247\201\346\225\260\346\215\256\347\261\273\345\236\213/description.json"
new file mode 100644
index 0000000000000000000000000000000000000000..08d4321b0b21b263b128022f6a7bcf82a89bc342
--- /dev/null
+++ "b/data/1.PostgreSQL\345\210\235\351\230\266/3.\346\237\245\350\257\242\346\225\260\346\215\256/4.\345\270\270\350\247\201\346\225\260\346\215\256\347\261\273\345\236\213/description.json"
@@ -0,0 +1,7 @@
+{
+  "type": "code_options",
+  "author": "ccat",
+  "source": "description.md",
+  "notebook_enable": false,
+  "exercise_id": "deb54053952b41b894e244277a9c1acf"
+}
\ No newline at end of file
diff --git "a/data/1.PostgreSQL\345\210\235\351\230\266/3.\346\237\245\350\257\242\346\225\260\346\215\256/4.\345\270\270\350\247\201\346\225\260\346\215\256\347\261\273\345\236\213/description.md" "b/data/1.PostgreSQL\345\210\235\351\230\266/3.\346\237\245\350\257\242\346\225\260\346\215\256/4.\345\270\270\350\247\201\346\225\260\346\215\256\347\261\273\345\236\213/description.md"
new file mode 100644
index 0000000000000000000000000000000000000000..d6a6033a579c2b92d1f2d8275db7deaf712f26c6
--- /dev/null
+++ "b/data/1.PostgreSQL\345\210\235\351\230\266/3.\346\237\245\350\257\242\346\225\260\346\215\256/4.\345\270\270\350\247\201\346\225\260\346\215\256\347\261\273\345\236\213/description.md"
@@ -0,0 +1,88 @@
+# 文本字段
+
+Joe 在设计订单表，他已经完成了下列内容：
+
+```postgresql
+create table orders (
+    id serial primary key,
+    item_id int,
+    amount int,
+    unit_price money,
+    price money,
+    ts timestamp default now()
+);
+```
+
+现在他需要给订单表加入一个 description 字段，这个字段需要保存订单的文字说明，这些文本不会超过两千字节， Joe 应该把建表语句修改为：
+
+## 答案
+
+```postgresql
+create table orders (
+    id serial primary key,
+    item_id int,
+    amount int,
+    unit_price money,
+    price money,
+    description text,
+    ts timestamp default now()
+);
+```
+
+## 选项
+
+### A
+
+```postgresql
+create table orders (
+    id serial primary key,
+    item_id int,
+    amount int,
+    unit_price money,
+    price money,
+    description char(2000),
+    ts timestamp default now()
+);
+```
+
+### B
+
+```postgresql
+create table orders (
+    id serial primary key,
+    item_id int,
+    amount int,
+    unit_price money,
+    price money,
+    description varchar(256) default '',
+    ts timestamp default now()
+);
+```
+
+### C
+
+```postgresql
+create table orders (
+    id serial primary key,
+    item_id int,
+    amount int,
+    unit_price money,
+    price money,
+    description text(2000),
+    ts timestamp default now()
+);
+```
+
+### D
+
+```postgresql
+create table orders (
+    id serial primary key,
+    item_id int,
+    amount int,
+    unit_price money,
+    price money,
+    description tinytext(2000),
+    ts timestamp default now()
+);
+```
\ No newline at end of file
diff --git "a/data/1.PostgreSQL\345\210\235\351\230\266/3.\346\237\245\350\257\242\346\225\260\346\215\256/4.\345\270\270\350\247\201\346\225\260\346\215\256\347\261\273\345\236\213/numbers.md" "b/data/1.PostgreSQL\345\210\235\351\230\266/3.\346\237\245\350\257\242\346\225\260\346\215\256/4.\345\270\270\350\247\201\346\225\260\346\215\256\347\261\273\345\236\213/numbers.md"
new file mode 100644
index 0000000000000000000000000000000000000000..31be887bb60bd9150e6da69b28b74a2e178d4d8d
--- /dev/null
+++ "b/data/1.PostgreSQL\345\210\235\351\230\266/3.\346\237\245\350\257\242\346\225\260\346\215\256/4.\345\270\270\350\247\201\346\225\260\346\215\256\347\261\273\345\236\213/numbers.md"
@@ -0,0 +1,45 @@
+# 数值的隐式类型转换
+
+Joe 需要使用下列表做一项数值计算
+
+```postgresql
+create table points(
+    id serial primary key,
+    x int,
+    y int
+);
+```
+
+计算查询为：
+
+```postgresql
+select id, (x^2 + y^2)/2 as result from points;
+```
+
+得到的结果集中，result 列的类型应该是：
+
+## 答案
+
+double
+
+## 选项
+
+### A
+
+float
+
+### B
+
+decimal
+
+### C
+
+int
+
+### D
+
+long
+
+### E
+
+byte
diff --git "a/data/3.PostgreSQL\351\253\230\351\230\266/3.SQL\351\253\230\347\272\247\346\212\200\345\267\247/2.Window Function/config.json" "b/data/3.PostgreSQL\351\253\230\351\230\266/3.SQL\351\253\230\347\272\247\346\212\200\345\267\247/2.Window Function/config.json"
index b9b3c61bffadc15fea4eb69b4828c996d242dd03..4b2fa42b501a5aa283caac56711f876748a93b7b 100644
--- "a/data/3.PostgreSQL\351\253\230\351\230\266/3.SQL\351\253\230\347\272\247\346\212\200\345\267\247/2.Window Function/config.json"	
+++ "b/data/3.PostgreSQL\351\253\230\351\230\266/3.SQL\351\253\230\347\272\247\346\212\200\345\267\247/2.Window Function/config.json"	
@@ -1,17 +1,15 @@
 {
   "keywords": [
-    "函数",
-    "function"
+    "window function"
   ],
   "children": [],
   "node_id": "pg-cab66a558cda467eabd9587b5a8257bd",
   "export": [
-    "salary.json"
+    "salary.json",
+    "distribute.json"
   ],
   "keywords_must": [
-    "函数",
-    "function",
-    "window"
+    "window function"
   ],
   "keywords_forbid": []
 }
\ No newline at end of file
diff --git "a/data/3.PostgreSQL\351\253\230\351\230\266/3.SQL\351\253\230\347\272\247\346\212\200\345\267\247/2.Window Function/distribute.json" "b/data/3.PostgreSQL\351\253\230\351\230\266/3.SQL\351\253\230\347\272\247\346\212\200\345\267\247/2.Window Function/distribute.json"
new file mode 100644
index 0000000000000000000000000000000000000000..fced6d89be0b13d89f1333b60f3bd44e65c87eff
--- /dev/null
+++ "b/data/3.PostgreSQL\351\253\230\351\230\266/3.SQL\351\253\230\347\272\247\346\212\200\345\267\247/2.Window Function/distribute.json"	
@@ -0,0 +1,7 @@
+{
+  "type": "code_options",
+  "author": "ccat",
+  "source": "distribute.md",
+  "notebook_enable": false,
+  "exercise_id": "9b4da19d895e4761a8946b0922693e38"
+}
\ No newline at end of file
diff --git "a/data/3.PostgreSQL\351\253\230\351\230\266/3.SQL\351\253\230\347\272\247\346\212\200\345\267\247/2.Window Function/distribute.md" "b/data/3.PostgreSQL\351\253\230\351\230\266/3.SQL\351\253\230\347\272\247\346\212\200\345\267\247/2.Window Function/distribute.md"
new file mode 100644
index 0000000000000000000000000000000000000000..4b62bcf88e03f86c4f8e7955fbddfcefcafde305
--- /dev/null
+++ "b/data/3.PostgreSQL\351\253\230\351\230\266/3.SQL\351\253\230\347\272\247\346\212\200\345\267\247/2.Window Function/distribute.md"	
@@ -0,0 +1,31 @@
+# 分布函数
+
+关于分布函数，以下说法正确的是
+
+1. `PERCENT_RANK()`函数是等级值百分比函数。
+2. `CUME_DIST()`函数主要用于查询小于或等于某个值的比例  
+    (number of partition rows preceding or peers with current row) / (total partition rows)
+3. `PERCENT_RANK() `按照 ` (rank - 1) / (total partition rows  - 1)` 计算， 其中，
+    rank 的值为使用RANK()函数产生的序号，rows的值为当前窗口的总记录数。
+
+## 答案
+
+全部都对
+
+## 选项
+
+### A
+
+```
+1, 2
+```
+
+### B
+
+```
+2, 3
+```
+
+### C
+
+全都不对
diff --git "a/data/3.PostgreSQL\351\253\230\351\230\266/4.\350\277\233\351\230\266\344\273\273\345\212\241/1.\346\225\260\346\215\256\345\272\223\351\227\256\347\255\224/qa.json" "b/data/3.PostgreSQL\351\253\230\351\230\266/4.\350\277\233\351\230\266\344\273\273\345\212\241/1.\346\225\260\346\215\256\345\272\223\351\227\256\347\255\224/qa.json"
index 989a85d32a3dfead74effc8e263a47103979c5ab..982172cb5d3d7fe192466c72479dace5dc34e2b0 100644
--- "a/data/3.PostgreSQL\351\253\230\351\230\266/4.\350\277\233\351\230\266\344\273\273\345\212\241/1.\346\225\260\346\215\256\345\272\223\351\227\256\347\255\224/qa.json"
+++ "b/data/3.PostgreSQL\351\253\230\351\230\266/4.\350\277\233\351\230\266\344\273\273\345\212\241/1.\346\225\260\346\215\256\345\272\223\351\227\256\347\255\224/qa.json"
@@ -4,7 +4,7 @@
   "depends": [],
   "type": "qa_task",
   "task_link": "https://ask.csdn.net/channel/20/tag/300001",
-  "task_info":{
+  "task_info": {
     "tag_name": "数据库"
   },
   "notebook_enable": false,
diff --git a/data/tree.json b/data/tree.json
index d360e548d70cf0241162a321509bdaf333e3823c..51372b9b1dfa022ede8dee3d059db7c4843c2255 100644
--- a/data/tree.json
+++ b/data/tree.json
@@ -29,8 +29,7 @@
                         "relational",
                         "rdbms"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -47,14 +46,12 @@
                         "服务器",
                         "客户端"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   }
                 ],
                 "keywords_must": [],
-                "keywords_forbid": [],
-                "group": 0
+                "keywords_forbid": []
               }
             },
             {
@@ -73,8 +70,7 @@
                       "keywords_must": [
                         "安装"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -89,8 +85,7 @@
                       "keywords_must": [
                         "登录"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -106,14 +101,12 @@
                         "基本用法",
                         "入门"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   }
                 ],
                 "keywords_must": [],
-                "keywords_forbid": [],
-                "group": 0
+                "keywords_forbid": []
               }
             },
             {
@@ -133,8 +126,7 @@
                       "keywords_must": [
                         "psql"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -149,8 +141,7 @@
                         "语法",
                         "SQL"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -170,20 +161,35 @@
                         "update",
                         "delete"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
+                    }
+                  },
+                  {
+                    "常见数据类型": {
+                      "node_id": "pg-3c400d541e81472e842be3355978c33a",
+                      "keywords": [
+                        "datetime",
+                        "text",
+                        "varchar",
+                        "int",
+                        "double",
+                        "float",
+                        "decimal",
+                        "timestamp"
+                      ],
+                      "children": [],
+                      "keywords_must": [],
+                      "keywords_forbid": []
                     }
                   }
                 ],
                 "keywords_must": [],
-                "keywords_forbid": [],
-                "group": 0
+                "keywords_forbid": []
               }
             }
           ],
           "keywords_must": [],
-          "keywords_forbid": [],
-          "group": 0
+          "keywords_forbid": []
         }
       },
       {
@@ -208,8 +214,7 @@
                         "表",
                         "table"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -224,8 +229,7 @@
                         "函数",
                         "function"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -250,8 +254,7 @@
                         "权限",
                         "privilege"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -270,8 +273,7 @@
                         "constraints",
                         "index"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -286,8 +288,7 @@
                         "trigger",
                         "触发器"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -303,14 +304,12 @@
                         "数据库扩展",
                         "extension"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   }
                 ],
                 "keywords_must": [],
-                "keywords_forbid": [],
-                "group": 0
+                "keywords_forbid": []
               }
             },
             {
@@ -331,8 +330,7 @@
                         "分组",
                         "聚合"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -347,8 +345,7 @@
                         "join",
                         "连接查询"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -363,8 +360,7 @@
                         "子查询",
                         "subquery"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -381,8 +377,7 @@
                         "limit",
                         "offset"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -397,8 +392,7 @@
                       "keywords_must": [
                         "cte"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -412,8 +406,7 @@
                       "keywords_must": [
                         "过程化"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -430,20 +423,17 @@
                         "授权",
                         "ddl"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   }
                 ],
                 "keywords_must": [],
-                "keywords_forbid": [],
-                "group": 0
+                "keywords_forbid": []
               }
             }
           ],
           "keywords_must": [],
-          "keywords_forbid": [],
-          "group": 0
+          "keywords_forbid": []
         }
       },
       {
@@ -469,8 +459,7 @@
                       "keywords_must": [
                         "standby"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -487,8 +476,7 @@
                         "流式复制",
                         "流复制"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -503,14 +491,12 @@
                         "外部数据连接",
                         "fdw"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   }
                 ],
                 "keywords_must": [],
-                "keywords_forbid": [],
-                "group": 0
+                "keywords_forbid": []
               }
             },
             {
@@ -530,8 +516,7 @@
                         "gis",
                         "几何"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -546,8 +531,7 @@
                         "json",
                         "jsonb"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -569,8 +553,7 @@
                         ],
                         ""
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -585,14 +568,12 @@
                         "视图",
                         "view"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   }
                 ],
                 "keywords_must": [],
-                "keywords_forbid": [],
-                "group": 0
+                "keywords_forbid": []
               }
             },
             {
@@ -614,25 +595,20 @@
                         "递归查询",
                         "recursive"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
                     "Window Function": {
                       "node_id": "pg-cab66a558cda467eabd9587b5a8257bd",
                       "keywords": [
-                        "函数",
-                        "function"
+                        "window function"
                       ],
                       "children": [],
                       "keywords_must": [
-                        "函数",
-                        "function",
-                        "window"
+                        "window function"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -649,8 +625,7 @@
                         "交叉透视表",
                         "pivot"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -666,8 +641,7 @@
                         "conflict",
                         "冲突"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -682,8 +656,7 @@
                         "事务",
                         "transaction"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   },
                   {
@@ -702,14 +675,12 @@
                         "performance",
                         "优化"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   }
                 ],
                 "keywords_must": [],
-                "keywords_forbid": [],
-                "group": 0
+                "keywords_forbid": []
               }
             },
             {
@@ -727,25 +698,21 @@
                       "keywords_must": [
                         "数据库问答"
                       ],
-                      "keywords_forbid": [],
-                      "group": 0
+                      "keywords_forbid": []
                     }
                   }
                 ],
                 "keywords_must": [],
-                "keywords_forbid": [],
-                "group": 0
+                "keywords_forbid": []
               }
             }
           ],
           "keywords_must": [],
-          "keywords_forbid": [],
-          "group": 0
+          "keywords_forbid": []
         }
       }
     ],
     "keywords_must": [],
-    "keywords_forbid": [],
-    "group": 0
+    "keywords_forbid": []
   }
 }
\ No newline at end of file