Hive: Merge Multiple Rows into One

In Hive, you can use certain aggregate functions and join functions to merge multiple rows of data into one row.

One approach is to use the aggregation function GROUP BY and the CONCAT_WS function. GROUP BY groups together the same column values, and then CONCAT_WS merges multiple rows of data within each group into a single row.

The example query is as follows:

SELECT col1, col2, CONCAT_WS(',', col3) as merged_col3
FROM your_table
GROUP BY col1, col2;

In the above query, col1 and col2 are columns used for grouping, while col3 is the column to be combined. The CONCAT_WS(‘,’, col3) function merges the multiple rows of data in the col3 column into one line using a comma as a separator, and returns the result as merged_col3.

Another option is to utilize the GROUP_CONCAT function. This function merges multiple rows of data within each group into a single string.

The example query is as follows:

SELECT col1, col2, GROUP_CONCAT(col3, ',') as merged_col3
FROM your_table
GROUP BY col1, col2;

In the above query, col1 and col2 are the columns used for grouping, while col3 is the column to be concatenated. The GROUP_CONCAT(col3, ‘,’) function combines the multiple rows of col3 column within each group into a single string, using a comma as a separator.

Select the appropriate method to merge multiple rows of data into one based on the specific requirements and data structure.