diff --git a/notes/Hive常用DDL操作.md b/notes/Hive常用DDL操作.md
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+# Hive常用DDL操作
+
+## 一、Database
+
+### 1.1 查看数据列表
+
+```sql
+show databases;
+```
+
+![hive-show-database](D:\BigData-Notes\pictures\hive-show-database.png)
+
+### 1.2 使用数据库
+
+```sql
+USE database_name;
+```
+
+### 1.3 新建数据库
+
+语法：
+
+```sql
+CREATE (DATABASE|SCHEMA) [IF NOT EXISTS] database_name   --DATABASE|SCHEMA是等价的
+  [COMMENT database_comment] --数据库注释
+  [LOCATION hdfs_path] --存储在HDFS上的位置
+  [WITH DBPROPERTIES (property_name=property_value, ...)]; --指定额外属性
+```
+
+示例：
+
+```sql
+CREATE DATABASE IF NOT EXISTS hive_test
+  COMMENT 'hive database for test'
+  WITH DBPROPERTIES ('create'='heibaiying');
+```
+
+
+
+### 1.4 查看数据库信息
+
+语法：
+
+```sql
+DESC DATABASE [EXTENDED] db_name; --EXTENDED 表示是否显示额外属性
+```
+
+示例：
+
+```sql
+DESC DATABASE  EXTENDED hive_test;
+```
+
+
+
+### 1.5 删除数据库
+
+语法：
+
+```sql
+DROP (DATABASE|SCHEMA) [IF EXISTS] database_name [RESTRICT|CASCADE];
+--默认行为是RESTRICT，如果数据库中存在表则删除失败。要想删除库及其中的表，可以使用CASCADE级联删除。
+```
+
+示例：
+
+```sql
+  DROP DATABASE IF EXISTS hive_test CASCADE;
+```
+
+
+
+## 二、创建表
+
+### 2.1 建表语法
+
+```sql
+CREATE [TEMPORARY] [EXTERNAL] TABLE [IF NOT EXISTS] [db_name.]table_name     --表名
+  [(col_name data_type [COMMENT col_comment],
+    ... [constraint_specification])]  --列名 列数据类型
+  [COMMENT table_comment]   --表描述
+  [PARTITIONED BY (col_name data_type [COMMENT col_comment], ...)]  --分区表分区规则
+  [CLUSTERED BY (col_name, col_name, ...) [SORTED BY (col_name [ASC|DESC], ...)] INTO num_buckets BUCKETS]  --分桶表分桶规则
+  [SKEWED BY (col_name, col_name, ...) ON ((col_value, col_value, ...), (col_value, col_value, ...), ...)  
+   [STORED AS DIRECTORIES] 
+  ]  --指定倾斜列和值
+  [
+   [ROW FORMAT row_format]    
+   [STORED AS file_format]
+     | STORED BY 'storage.handler.class.name' [WITH SERDEPROPERTIES (...)]  
+  ]  -- 指定行分隔符、存储文件格式或采用自定义存储格式
+  [LOCATION hdfs_path]  -- 指定表的存储位置
+  [TBLPROPERTIES (property_name=property_value, ...)]  --指定表的属性
+  [AS select_statement];   --从查询结果创建表
+```
+
+### 2.2 内部表
+
+```sql
+  CREATE TABLE emp(
+    empno INT,
+    ename STRING,
+    job STRING,
+    mgr INT,
+    hiredate TIMESTAMP,
+    sal DECIMAL(7,2),
+    comm DECIMAL(7,2),
+    deptno INT)
+    ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t";
+```
+
+### 2.3 外部表
+
+```sql
+  CREATE EXTERNAL TABLE emp_external(
+    empno INT,
+    ename STRING,
+    job STRING,
+    mgr INT,
+    hiredate TIMESTAMP,
+    sal DECIMAL(7,2),
+    comm DECIMAL(7,2),
+    deptno INT)
+    ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t"
+    LOCATION '/hive/emp_external';
+```
+
+使用 `desc format  emp_external`命令可以查看表的详细信息如下：
+
+![hive-external-table](D:\BigData-Notes\pictures\hive-external-table.png)
+
+### 2.4 分区表
+
+```sql
+  CREATE EXTERNAL TABLE emp_partition(
+    empno INT,
+    ename STRING,
+    job STRING,
+    mgr INT,
+    hiredate TIMESTAMP,
+    sal DECIMAL(7,2),
+    comm DECIMAL(7,2)
+    )
+    PARTITIONED BY (deptno INT)   -- 按照部门编号进行分区
+    ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t"
+    LOCATION '/hive/emp_partition';
+```
+
+### 2.5 分桶表
+
+```sql
+  CREATE EXTERNAL TABLE emp_bucket(
+    empno INT,
+    ename STRING,
+    job STRING,
+    mgr INT,
+    hiredate TIMESTAMP,
+    sal DECIMAL(7,2),
+    comm DECIMAL(7,2)
+    )
+    CLUSTERED BY(empno) SORTED BY(empno ASC) INTO 4 BUCKETS  --按照员工编号散列到四个bucket中
+    ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t"
+    LOCATION '/hive/emp_bucket';
+```
+
+### 2.6 倾斜表
+
+```sql
+  CREATE EXTERNAL TABLE emp_skewed(
+    empno INT,
+    ename STRING,
+    job STRING,
+    mgr INT,
+    hiredate TIMESTAMP,
+    sal DECIMAL(7,2),
+    comm DECIMAL(7,2)
+    )
+    SKEWED BY (empno) ON (66,88,100)  --指定数据倾斜
+    ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t"
+    LOCATION '/hive/emp_skewed';   
+```
+
+### 2.7 临时表
+
+临时表仅对当前session可见。数据将存储在用户的暂存目录中，并在会话结束时删除。如果临时表与永久表表名相同，则对该表名的任何引用都将解析为临时表，而不是永久表。临时表具有以下限制：
+
+如果使用数据库中已存在的永久表的数据库/表名创建临时表，则在该会话中，对该表的任何引用都将解析为临时表，而不是永久表。如果不删除临时表或将其重命名为非冲突名称，用户将无法访问该会话中的原始表。
+
++ 不支持分区列；
++ 不支持创建索引。
+
+```sql
+  CREATE TEMPORARY TABLE emp_temp(
+    empno INT,
+    ename STRING,
+    job STRING,
+    mgr INT,
+    hiredate TIMESTAMP,
+    sal DECIMAL(7,2),
+    comm DECIMAL(7,2)
+    )
+    ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t";
+```
+
+### 2.8 CTAS创建表
+
+支持从查询语句的结果创建表：
+
+```sql
+CREATE TABLE emp_copy AS SELECT * FROM emp WHERE deptno='20';
+```
+
+### 2.9 复制表结构
+
+语法：
+
+```sql
+CREATE [TEMPORARY] [EXTERNAL] TABLE [IF NOT EXISTS] [db_name.]table_name  --创建表表名
+   LIKE existing_table_or_view_name  --被复制表的表名
+   [LOCATION hdfs_path]; --存储位置
+```
+
+示例：
+
+```sql
+CREATE TEMPORARY EXTERNAL TABLE  IF NOT EXISTS  emp_co  LIKE emp
+```
+
+
+
+### 2.10 加载数据到表
+
+加载数据到表中属于DML操作，不属于本小节讲解的DDL操作，这里为了方便大家测试，所以先简单介绍一下加载本地数据到表中：
+
+```sql
+-- 加载数据到emp表中
+load data local inpath "/usr/file/emp.txt" into table emp;
+```
+
+其中emp.txt的文件内容如下，你可以直接复制粘贴，也可以到本仓库的resources目录下载对应的文件：
+
+```txt
+7369	SMITH	CLERK	7902	1980-12-17 00:00:00	800.00		20
+7499	ALLEN	SALESMAN	7698	1981-02-20 00:00:00	1600.00	300.00	30
+7521	WARD	SALESMAN	7698	1981-02-22 00:00:00	1250.00	500.00	30
+7566	JONES	MANAGER	7839	1981-04-02 00:00:00	2975.00		20
+7654	MARTIN	SALESMAN	7698	1981-09-28 00:00:00	1250.00	1400.00	30
+7698	BLAKE	MANAGER	7839	1981-05-01 00:00:00	2850.00		30
+7782	CLARK	MANAGER	7839	1981-06-09 00:00:00	2450.00		10
+7788	SCOTT	ANALYST	7566	1987-04-19 00:00:00	1500.00		20
+7839	KING	PRESIDENT		1981-11-17 00:00:00	5000.00		10
+7844	TURNER	SALESMAN	7698	1981-09-08 00:00:00	1500.00	0.00	30
+7876	ADAMS	CLERK	7788	1987-05-23 00:00:00	1100.00		20
+7900	JAMES	CLERK	7698	1981-12-03 00:00:00	950.00		30
+7902	FORD	ANALYST	7566	1981-12-03 00:00:00	3000.00		20
+7934	MILLER	CLERK	7782	1982-01-23 00:00:00	1300.00		10
+```
+
+加载后可查询表中数据：
+
+![hive-select-emp](D:\BigData-Notes\pictures\hive-select-emp.png)
+
+
+
+## 三、修改表
+
+### 3.1 重命名表
+
+语法：
+
+```sql
+ALTER TABLE table_name RENAME TO new_table_name;
+```
+
+示例：
+
+```sql
+ALTER TABLE emp_temp RENAME TO new_emp; --把emp_temp表重命名为new_emp
+```
+
+
+
+### 3.2 修改列
+
+语法：
+
+```sql
+ALTER TABLE table_name [PARTITION partition_spec] CHANGE [COLUMN] col_old_name col_new_name column_type
+  [COMMENT col_comment] [FIRST|AFTER column_name] [CASCADE|RESTRICT];
+```
+
+示例：
+
+```sql
+-- 修改字段名和类型
+ALTER TABLE emp_temp CHANGE empno empno_new INT;
+ 
+-- 修改字段sal的名称 并将其放置到empno字段后
+ALTER TABLE emp_temp CHANGE sal sal_new decimal(7,2)  AFTER ename;
+
+-- 为字段增加注释
+ALTER TABLE emp_temp CHANGE mgr mgr_new INT COMMENT 'this is column mgr';
+```
+
+
+
+### 3.3 新增列
+
+示例：
+
+```sql
+ALTER TABLE emp_temp ADD COLUMNS (address STRING COMMENT 'home address');
+```
+
+
+
+### 3.4 修改分区
+
diff --git a/notes/Hive数据类型和文件格式.md b/notes/Hive数据类型和文件格式.md
index 54f1b27..5f18345 100644
--- a/notes/Hive数据类型和文件格式.md
+++ b/notes/Hive数据类型和文件格式.md
@@ -17,7 +17,7 @@ Hive表中的列支持以下基本数据类型：
 | **Integers（整型）**                    | TINYINT—1字节的有符号整数 <br/>SMALLINT—2字节的有符号整数<br/> INT—4字节的有符号整数<br/> BIGINT—8字节的有符号整数 |
 | **Boolean（布尔型）**                   | BOOLEAN—TRUE/FALSE                                           |
 | **Floating point numbers（浮点型）**    | FLOAT— 单精度浮点型 <br/>DOUBLE—双精度浮点型                 |
-| **Fixed point numbers（定点数）**       | DECIMAL—用户自定义精度定点数，比如2.4，3.68                  |
+| **Fixed point numbers（定点数）**       | DECIMAL—用户自定义精度定点数，比如DECIMAL(7,2)               |
 | **String types（字符串）**              | STRING—指定字符集的字符序列<br/> VARCHAR—具有最大长度限制的字符序列 <br/>CHAR—固定长度的字符序列 |
 | **Date and time types（日期时间类型）** | TIMESTAMP —  时间戳 <br/>TIMESTAMP WITH LOCAL TIME ZONE — 时间戳，纳秒精度<br/> DATE—日期类型 |
 | **Binary types（二进制类型）**          | BINARY—字节序列                                              |
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diff --git a/resources/emp.txt b/resources/emp.txt
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+++ b/resources/emp.txt
@@ -0,0 +1,14 @@
+7369	SMITH	CLERK	7902	1980-12-17 00:00:00	800.00		20
+7499	ALLEN	SALESMAN	7698	1981-02-20 00:00:00	1600.00	300.00	30
+7521	WARD	SALESMAN	7698	1981-02-22 00:00:00	1250.00	500.00	30
+7566	JONES	MANAGER	7839	1981-04-02 00:00:00	2975.00		20
+7654	MARTIN	SALESMAN	7698	1981-09-28 00:00:00	1250.00	1400.00	30
+7698	BLAKE	MANAGER	7839	1981-05-01 00:00:00	2850.00		30
+7782	CLARK	MANAGER	7839	1981-06-09 00:00:00	2450.00		10
+7788	SCOTT	ANALYST	7566	1987-04-19 00:00:00	1500.00		20
+7839	KING	PRESIDENT		1981-11-17 00:00:00	5000.00		10
+7844	TURNER	SALESMAN	7698	1981-09-08 00:00:00	1500.00	0.00	30
+7876	ADAMS	CLERK	7788	1987-05-23 00:00:00	1100.00		20
+7900	JAMES	CLERK	7698	1981-12-03 00:00:00	950.00		30
+7902	FORD	ANALYST	7566	1981-12-03 00:00:00	3000.00		20
+7934	MILLER	CLERK	7782	1982-01-23 00:00:00	1300.00		10