Impala中行转列在合并列

Impala中如何实现将多列转为一行，其实Impala中自带函数可以实现，不用自定义函数。

下面我开始演示：

-bash-4.1$ impala-shell

Starting Impala Shell without Kerberos authentication
Connected to cdha:21000
Server version: impalad version 1.4.2-cdh5 RELEASE (build eac952d4ff674663ec3834778c2b981b252aec78)
Welcome to the Impala shell. Press TAB twice to see a list of available commands.Copyright (c) 2012 Cloudera, Inc. All rights reserved.(Shell build version: Impala Shell v1.4.2-cdh5 (eac952d) built on Tue Sep 16 19:15:40 PDT 2014)

[cdha:21000] > create table student(name string,subject string,score decimal(4,1));    -------------创建演示表：student(脱离学校四年了，还不忘自己是学生^_^)
Query: create table student(name string,subject string,score decimal(4,1))Returned 0 row(s) in 1.97s
[cdha:21000] > insert into student values('xiaoming','math',89.5); ----------------插入演示数据 (小明和花花的学习成绩，他们感情比较好)
Query: insert into student values('xiaoming','math',89.5)
Inserted 1 rows in 2.56s
[cdha:21000] > insert into student values('xiaoming','english',92);
Query: insert into student values('xiaoming','english',92)
Inserted 1 rows in 0.39s
[cdha:21000] > insert into student values('xiaoming','chinese',98);
Query: insert into student values('xiaoming','chinese',98)
Inserted 1 rows in 0.42s
[cdha:21000] > insert into student values('huahua','chinese',80);
Query: insert into student values('huahua','chinese',80)
Inserted 1 rows in 0.40s
[cdha:21000] > insert into student values('huahua','math',89.5);
Query: insert into student values('huahua','math',89.5)
Inserted 1 rows in 0.29s
[cdha:21000] > select * from student;    ----------每次考完试，老师报分数时都很紧张
Query: select * from student
+----------+---------+-------+
| name     | subject | score |
+----------+---------+-------+
| xiaoming | english | 92.0  |
| huahua   | chinese | 80.0  |
| xiaoming | chinese | 98.0  |
| huahua   | math    | 89.5  |
| xiaoming | math    | 89.5  |
+----------+---------+-------+
Returned 5 row(s) in 0.23s[cdha:21000] > select name,group_concat(subject,',') from student group by  name;  ------------小试牛刀，看到了吧，多列拼接到一起了
Query: select name,group_concat(subject,',') from student group by  name
+----------+----------------------------+
| name     | group_concat(subject, ',') |
+----------+----------------------------+
| xiaoming | english,chinese,math       |
| huahua   | chinese,math               |
+----------+----------------------------+
Returned 2 row(s) in 0.38s------------下面演示有价值的示例，显示高手之招，呵呵------------这样就可以在一行上面，看到小明和花花的各科成绩了[cdha:21000] > select name,group_concat(concat_ws('=',subject,cast(score as string)),',') from student group by  name;
Query: select name,group_concat(concat_ws('=',subject,cast(score as string)),',') from student group by  name
+----------+-------------------------------------------------------------------+
| name     | group_concat(concat_ws('=', subject, cast(score as string)), ',') |
+----------+-------------------------------------------------------------------+
| xiaoming | english=92.0,chinese=98.0,math=89.5                               |
| huahua   | chinese=80.0,math=89.5                                            |
+----------+-------------------------------------------------------------------+
Returned 2 row(s) in 0.39s
[cdha:21000] >

Impala中行转列在合并列相关推荐

oracle 查询列合并行,Oracle 查询合并列
在ORACLE 查询时,有时要将多个列合并成一行,其方法如下: 1. decode 函数 decode 函数的语法为: decode(条件,值1,返回值1,值2,返回值2,...值n,返回值n,缺省 ...
table html 合并列,html table上下行合并
colspan 是合并列,rowspan是合并行,合并行的时候,比如rowspan="2",它的下一行tr会少一列:合并列的时候 colspan="2",此行的 ...
elementui table 固定列_elementUI Table组件如何设置合并列
效果图: image.png 代码如下: :data="tableData" style="width:200px" :border="true&qu ...
GRIDVIEW多行多列合并单元格（合并列）
GitHub项目地址:https://github.com/mingceng/merge-gridviewcell 去年的时候,我写了两篇文章: GridView多行多列合并单元格(完整代码和例子) ...
Excel:有合并列和横排多行的每个单元格数据与首列组合竖排
需求如图: 左侧表格转为右侧的,注意:有合并列和多行解决方法: (1)选中(单击)数据表中任意格子,以定位数据来源表格 (2)数据--获取数据--自其他源--自表格/区域步骤如图: (3) 在弹出 ...
layui框架实现table某一列的合并+冻结（合并列+fixed冻结二者发生冲突）
1.先实现的合并(百度上有很多),我用的是这个博主的京兆文鱼博主的:合并列的代码 2.对1中已经完成合并的这一列进行"冻结",我用的是layui框架自带的fixed属性(不知道的 ...
SQL Server 2005合并列成字符串 2008-11-07
SQL Server 2005合并列成字符串 2008-11-07 如果要将数据中的某一列合并成字符串,形成 A,B,C 这样的格式的话,一般性代码如下 DECLARE @str nvarchar(4 ...
SQL 合并列值和拆分列值
合并列值表结构,数据如下: view plain id value ----- ------ 1 aa 1 bb 2 aaa 2 bbb 2 ccc 需要得到结果: id values ------ ...
poi 操作导出excel 合并列
今天导出excel模板时需要加入标题,原有的方法没有添加标题的功能,只能修改了 // 标题 Row title = sheet.createRow(0); //填充标题内容 this.createCe ...

Impala中行转列在合并列

Impala中行转列在合并列

Impala中行转列在合并列相关推荐

最新文章

热门文章