generate where clause in bash using variables

Question

I have some variables in bash like below.

min_date=\'2020-06-06\'
max_date=\'2020-06-08\'
max_seq_min_date=1  --This is till where data is processe         


        

Answer 1

It will be more efficient to make minor changes to the query - making it easier to generate (equivalent) SQL dynamically.

It uses "between" operator to avoid variable length lists for the 'in (...)' conditions.

Note comment about 1=1, it is kept as per question, but need to be reviewed, as it will always make the condition pass.

min_date='2020-06-06'
max_date='2020-06-08'
max_seq_min_date=1
max_seq_max_date=3

echo "
WHERE 1 = 1 or case
    when batch_date = '$min_date' then seq_num between 1 and $max_seq_min_date
    when batch_date = '$max_date' then seq_num between 1 and $max_seq_max_date
    when batch_date between '$min_date' and '$max_date' then seq_num between 1 and 4
    else false
    end
" 

I do NOT have mysql, but the above works for Postgresql.

Answer 2

Just use interpolation, i.e.

sql_clause="... batch_date = '$min_date' and seq_num in ('2','3', '4') ...."