利用Hive中concat_ws函数将多行记录合并成一行

1. 创建测试表

    CREATE TABLE IF NOT EXISTS TEST.USERS (
        id string,
        k1 string,
        k2 string,
        k3 string
    ) COMMENT '用户表' 
    ROW FORMAT delimited fields terminated BY '\t' 
    STORED AS TEXTFILE;
   

2. 插入测试数据

    INSERT OVERWRITE TABLE test.users VALUES
    ('1','a1','a2','a3'),
    ('1','a11','a22','a33'),
    ('1','a111','a222','a333'),
    ('2','b1','b2','b3'),
    ('2','b11','b22','b33');
   

   查看
   

3. 将多行数据转为一行

    SELECT id,concat('[',concat_ws( ',',
                            collect_set(
                                        concat(
                                               '{',
                                               '"k1":"',k1,
                                               '","k2":"',k2,
                                               '","k3":"',k3,
                                               '"}'
                                               )
                                        )
                            ),
                  ']'
                  )
    FROM test.users
    GROUP BY id;
   

```sql
SELECT id,
       concat(
              '[{',
              concat_ws(
                         '},{',
                         collect_set(
                                     concat(
                                            '"k1":"',k1,
                                             '","k2":"',k2,
                                             '","k3":"',k3,
                                             '"' 
                                            )
                                      )
                        ),
                '}]'
               )
FROM test.users
GROUP BY id