MYSQL - Create single sql query from multiple query - php

Question

I am using MYSQL Adminer 4.8.0 4.8.1
I am trying to form a single query from below select queries,
is their any way ir can be done?
There are 4-5 queries so i am afraid
SELECT `value` from `core_config_data`
WHERE `path` = 'catalog/product/base_media_url';
SELECT `label`
FROM `catalog_product_entity_media_gallery_value`
WHERE `value_id` = (SELECT `value_id`
FROM `catalog_product_entity_media_gallery`
WHERE `value` LIKE '%test%')
LIMIT 1;
SELECT `child_id`
FROM `catalog_product_relation`
WHERE `parent_id` = 9622
LIMIT 1;
SELECT `rule_price`
FROM `catalogrule_product_price`
WHERE `product_id` = 9622
LIMIT 1;
SELECT value
FROM `catalog_product_entity_decimal`
WHERE `row_id` = 9622 AND `attribute_id` IN (SELECT `attribute_id` FROM `eav_attribute`
WHERE `attribute_code` IN ('price','special_price'))
SELECT `value`
FROM `core_config_data`
WHERE `scope` = 'websites' AND `path` = 'currency/options/default' AND `scope_id` = 3';
SELECT e.sku,value from catalog_product_entity e
inner join catalog_product_entity_varchar v on e.entity_id = v.row_id and e.entity_id = 9622 and
attribute_id IN (select attribute_id from eav_attribute where attribute_code IN ('name','sku'));
```
It would be very very helpful, if i get single query for this. Not sure if its easy to do it. but i am quite new in mysql so not getting exaclty.
I have tried using UNION but that won't work.
I have tried
SELECT parent.entity_id AS parent_id,
simple.entity_id AS simple_id,
parent.sku AS sku, simple.sku AS simple_sku
ccd.value AS base_media_url
FROM catalog_product_entity AS parent
JOIN catalog_product_super_link AS link ON parent.row_id = link.parent_id
JOIN catalog_product_entity AS simple ON link.product_id = simple.entity_id
LEFT JOIN core_config_data AS ccd ON path = 'catalog/product/base_media_url'
WHERE parent.entity_id IN (9244) LIMIT 1
but it is not working.

Answer 1

Technique 1: Combining scalars:
SELECT a ... LIMIT 1;
SELECT b ... LIMIT 1;
-->
SELECT
( SELECT a ... LIMIT 1) AS a,
( SELECT b ... LIMIT 1) AS b ;
If a is something like COUNT(*), then you know that there will be exactly one result; hence the LIMIT 1 is unnecessary.
If one of those subqueries might not return any rows, then you get NULL.
Technique 2: A select can be used almost anywhere an expression can be used. The above is, technically, an example of such. Also...
SELECT ... WHERE x = ( SELECT ... ) ...
Again, the subquery must return a single row to make that possible.
SELECT ...
WHERE x LIKE CONCAT('%', ( SELECT ... ), '%')
...;
That becomes something like this after the subquery is evaluated:
SELECT
WHERE x LIKE '%foo%'
...;
(It is not efficient, but it works.)
These 3 are similar, but not necessarily efficient as each other:
SELECT ...
WHERE x IN ( SELECT ... )
SELECT ... FROM A
WHERE EXISTS( SELECT ... FROM B
WHERE B.x = A.x )
SELECT ... FROM A JOIN B ON B.x = A.x
This is similar but finds the matching items that are missing from B:
SELECT ... FROM A LEFT JOIN B ON B.x = A.x
WHERE B.id IS NULL
UNION should be used for queries that have similar output:
SELECT x,y FROM A
UNION
SELECT x,y FROM B
That will produce any number of rows from A and any number of rows from B. Duplicates are removed if you use UNION DISTINCT, or kept if you use UNION ALL.
ORDER BY ... LIMIT ... gets tricky. OFFSET gets even trickier.
Performance
Avoid IN ( SELECT ...) it is usually the slower of the three.
Avoid leading wildcards in LIKE; see if FULLTEXT would be a better option.
INDEX(path), INDEX(parent_id, child_id) ("covering"), INDEX(scope, path, scope_id); maybe others, but I need to see SHOW CREATE TABLE.
Avoid EAV schema; it is bad for performance. I added a link; see the many other discussions. Also: http://mysql.rjweb.org/doc.php/eav and http://mysql.rjweb.org/doc.php/index_cookbook_mysql#speeding_up_wp_postmeta
Those items are probably more important (to performance) than combining the statements together. See https://meta.stackexchange.com/questions/66377/what-is-the-xy-problem

Answer 2

Write a Stored Procedure, then CALL it.
Declaration:
DELIMITER //
CREATE PROCEDURE foo(...)
...
BEGIN
statement 1;
statement 2;
statement 3;
statement 4;
statement 5;
END //
DELIMITER ;
Invocation:
CALL foo(...);