1 语法树
[WITH CommonTableExpression (, CommonTableExpression)*]
SELECT [ALL | DISTINCT] select_expr, select_expr, ...
FROM table_reference
[WHERE where_condition]
[GROUP BY col_list]
[ORDER BY col_list]
[CLUSTER BY col_list
| [DISTRIBUTE BY col_list] [SORT BY col_list]
]
[LIMIT [offset,] rows]
table_reference指示查询的输入。它可以是普通物理表,视图,join查询结果或子查询结果。
表名和列名不区分大小写。
2 案例:美国Covid-19新冠select查询
下面来准备一下语法测试环境,在附件资料中有一份数据文件《us-covid19-counties.dat》,里面记录了2021-01-28美国各个县累计新冠确诊病例数和累计死亡病例数。
在Hive中创建表,加载该文件到表中:
--step1:创建普通表t_usa_covid19
drop table handsome.t_usa_covid19;
CREATE TABLE handsome.t_usa_covid19(
count_date string,
county string,
state string,
fips int,
cases int,
deaths int)
row format delimited fields terminated by ",";
--将源数据load加载到t_usa_covid19表对应的路径下
loa