Find_in_set feature of MySQL to find elements in an array or list of Values - Example and Diagrams

In an earlier post , we have seen how using group_concat() function we can group all the values of a column into comma separated array/list of values.

Please see the picture below:

Array elements distributed over 5 different rows and needs to be merged

On doing a group_concat(eligibility_file_staging_complete_id), we get the values in all the rows into a single row.

Example query:

select group_concat(eligibility_file_staging_complete_id)into @v_staging_id_list from temp_multiple_mc_complete;

select @v_staging_id_list;

Merge all columns into a single array using group_concat() function

Now, our requirement is to find each ID from another table and do some operation if the match is found.
We can use the FIND_IN_SET() function for this.

Example query:

  select efsc.eligibility_file_staging_complete_id as reference_id, efsc.* from
eligibility_file_staging_complete as efsc
where find_in_set(efsc.eligibility_file_staging_complete_id , @v_staging_id_list)
and file_id = v_file_id;

The above query will pick only those rows that are in the array @v_staging_id_list.

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