How to replace multiple values in a single column with SQL? - mysql

Question

I have a column with complex user id. I want to replace the text within my select query.
This creates a new column as updated_by for every single value. I want them to be replaced in a single column. How can I achieve this?
select replace(updated_by, '5eaf5d368141560012161636', 'A'),
replace(updated_by, '5e79d03e9abae00012ffdbb3', 'B'),
replace(updated_by, '5e7b501e9abae00012ffdbd6', 'C'),
replace(updated_by, '5e7b5b199abae00012ffdbde', 'D'),
replace(updated_by, '5e7c817c9ca5540012ea6cba', 'E'),
updated_by
from my_table
GROUP BY updated_by;

Answer 1

In Postgres I would use a VALUES expression to form a derived table:
To just select:
SELECT *
FROM my_table m
JOIN (
VALUES
('5eaf5d368141560012161636', 'A')
, ('5e79d03e9abae00012ffdbb3', 'B')
, ('5e7b501e9abae00012ffdbd6', 'C')
, ('5e7b5b199abae00012ffdbde', 'D')
, ('5e7c817c9ca5540012ea6cba', 'E')
) u(updated_by, new_value) USING (updated_by);
Or LEFT JOIN to include rows without replacement.
You may need explicit type casts with non-default data types. See:
Casting NULL type when updating multiple rows
For repeated use, create a persisted translation table.
CREATE TABLE updated_by_translation (updated_by text PRIMARY KEY, new_value text);
INSERT INTO my_table
VALUES
('5eaf5d368141560012161636', 'A')
, ('5e79d03e9abae00012ffdbb3', 'B')
, ('5e7b501e9abae00012ffdbd6', 'C')
, ('5e7b5b199abae00012ffdbde', 'D')
, ('5e7c817c9ca5540012ea6cba', 'E')
;
Data types and constraints according to your actual use case.
SELECT *
FROM my_table m
LEFT JOIN updated_by_translation u USING (updated_by);
MySQL recently added a VALUES statement, too. The manual:
VALUES is a DML statement introduced in MySQL 8.0.19
But it requires the keyword ROW for every row. So:
...
VALUES
ROW('5eaf5d368141560012161636', 'A')
, ROW('5e79d03e9abae00012ffdbb3', 'B')
, ROW('5e7b501e9abae00012ffdbd6', 'C')
, ROW('5e7b5b199abae00012ffdbde', 'D')
, ROW('5e7c817c9ca5540012ea6cba', 'E')
...

Answer 2

Use case:
select case updated_by
when '5eaf5d368141560012161636' then 'A'
when '5e79d03e9abae00012ffdbb3' then 'B'
when '5e7b501e9abae00012ffdbd6' then 'C'
when '5e7b5b199abae00012ffdbde' then 'D'
when '5e7c817c9ca5540012ea6cba' then 'E'
end as updated_by
from my_table

Answer 3

This has to be nested liek this
SELECT
REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(updated_by,
'5e7c817c9ca5540012ea6cba',
'E'),
'5e7b5b199abae00012ffdbde',
'D'),
'5e7b501e9abae00012ffdbd6',
'C'),
'5e79d03e9abae00012ffdbb3',
'B'),
'5eaf5d368141560012161636',
'A'),
updated_by
FROM
my_table
GROUP BY updated_by
This will replace all occurring, patterns, if they are not foung nothing happens

Answer 4

You can use a recursive CTE if you need to handle multiple values within a single row:
with replacements as (
select '5eaf5d368141560012161636' as oldval, 'A' as newval union all
select '5e79d03e9abae00012ffdbb3' as oldval, 'B' union all
select '5e7b501e9abae00012ffdbd6' as oldval, 'C' union all
select '5e7b5b199abae00012ffdbde' as oldval, 'D' union all
select '5e7c817c9ca5540012ea6cba' as oldval, 'E'
),
r as (
select r.*, row_number() over (order by oldval) as seqnum
from replacements r
),
recursive cte (
select r.seqnum, replace(t.updated_by, r.oldval, r.newval) as updated_by
from my_table t join
r
on r.seqnum = 1
union all
select r.seqnum, replace(cte.updated_by, r.oldval, r.newval) as updated_by
from cte t join
r
on r.seqnum = cte.seqnum + 1
)
select cte.*
from cte
where seqnum = (select count(*) from replacements);