当该信息是同一表中 GROUP CONCAT 的结果时，如何更新记录中的列？

Question

I cannot determine if this should be something nested or a JOIN.

Each record has three values from the column value across from their name in the column variable .

I have a successful GROUP CONCAT that combines them into a single text string.

BUT, I need to UPDATE/INSERT the concat value into another variable=>value pair.

Such as this. I want each person to have "cityStateZip" in the value for `cust_abc'.

I believe it's "INSERT" and not update since none of the records have anything in cust_abc yet. But, I'm not quite sure if it shouldn't be UPDATE.

id_member	variable	value
1234	cust_abc	"should show citystatezip"
1234	cust_a	city
1234	cust_b	state
1234	cust_c	zip

I can't get past the error of having the target table being the same in the SELECT FROM.

I was attempting things like:

INSERT INTO smgqg_themes.value (my group concat) WHEN `variable` = "cust_abc"

This is the group concat that works fine to make the string:

SELECT GROUP_CONCAT
( `value` 
order by case variable 
when 'cust_a' then 1 
when 'cust_b' then 2 else 3 end
SEPARATOR '') 
output
FROM smfqg_themes
WHERE `id_member` IN (1234, 1235, 1236, etc) 
AND `variable`  IN ('cust_a', 'cust_b', 'cust_c')

Answer 1

You can INSERT into a the same table you SELECT from in the same SQL statement. I do this all the time.

The syntax is:

INSERT INTO <tablename> (<columns...>)
SELECT ...;

The SELECT must return the same columns that you name in the INSERT clause, in the same order.

If you want an existing row to be updated, but still insert a row if one is missing with the 'cust_abc' varible, then you can use INSERT...ON DUPLICATE KEY UPDATE:

INSERT INTO smgqg_themes (id_member, variable, value)
SELECT id_member, 'cust_abc', 
  GROUP_CONCAT(`value` 
    ORDER BY CASE variable 
    WHEN 'cust_a' THEN 1 
    WHEN 'cust_b' THEN 2 ELSE 3 END
    SEPARATOR '') as v
FROM smgqg_themes
WHERE `id_member` IN (1234, 1235, 1236) 
  AND `variable` IN ('cust_a', 'cust_b', 'cust_c')
GROUP BY `id_member`
ON DUPLICATE KEY UPDATE value = VALUES(value);

Demo: https://dbfiddle.uk/OPJQ1ZXF