sql declare select calcuation as variable for further use in query

Question

I want to change a specific calculation inside a select query to a variable in order to re-process the result for other calculations inside the query. In this example the value I need as variable is dt_raw . So far I wasn't successful with implementing a solution.

SELECT
cpe.entity_id AS product_id,
cpe.sku,
CASE
    WHEN (csi.qty - csi.stock_ordered_qty) >= cped2.value AND csi.stock_id = 3  /* on stock burgsdorgstrasse */
        THEN 3
    WHEN (csi.qty - csi.stock_ordered_qty) >= cped2.value AND csi.stock_id = 4  /* on stock hoppegarten */
        THEN 7
    WHEN sum(sm_qty) > 2 AND csi.stock_id = 3                       /* history burgsdorfstrasse */
        THEN round(avg(DATEDIFF(sm.sm_date, po.po_date)) + 3)
    WHEN sum(sm_qty) > 2 AND csi.stock_id = 4                       /* history hoppegarten */
        THEN round(avg(DATEDIFF(sm.sm_date, po.po_date)) + 4)
        ELSE cped.value                                             /* default_delivery_time */
    END AS dt_raw


FROM `test_live`.`catalog_product_entity` cpe

LEFT JOIN `test_live`.`cataloginventory_stock_item` csi
ON cpe.entity_id = csi.product_id

LEFT JOIN `test_live`.`catalog_product_entity_decimal` cped     /* default_delivery_time */
ON cpe.entity_id = cped.entity_id
AND cped.attribute_id = 392

LEFT JOIN `test_live`.`catalog_product_entity_decimal` cped2    /* min_qty_delivery_time */
ON cpe.entity_id = cped2.entity_id
AND cped2.attribute_id = 393

LEFT JOIN `test_live`.`stock_movement` sm
ON cpe.entity_id = sm.sm_product_id
AND sm.sm_type = "supply"
AND sm.sm_date > NOW() - Interval 90 DAY

LEFT JOIN `test_live`.`purchase_order` po
ON po.po_num = sm.sm_po_num


WHERE
csi.is_favorite_warehouse = 1
AND (csi.stock_id = 3 OR csi.stock_id = 4)

GROUP BY cpe.entity_id

I want to use the results of dt_raw in further calcuations.

eg:

concat ("ca. ", round(dt_raw), " weeks") as delivery_time

CASE
    WHEN dt_raw <= 30
    THEN 50
    ELSE 0
END AS amazon_qty

Answer 1

If you want to use your query result without restictions you should save it in a table. After that use a select to get the data you want.

CREATE

CREATE TABLE your_schema.dt_raw_temp
SELECT
cpe.entity_id AS product_id,
cpe.sku,
CASE
    WHEN (csi.qty - csi.stock_ordered_qty) >= cped2.value AND csi.stock_id = 3  /* on stock burgsdorgstrasse */
        THEN 3
    WHEN (csi.qty - csi.stock_ordered_qty) >= cped2.value AND csi.stock_id = 4  /* on stock hoppegarten */
        THEN 7
    WHEN sum(sm_qty) > 2 AND csi.stock_id = 3                       /* history burgsdorfstrasse */
        THEN round(avg(DATEDIFF(sm.sm_date, po.po_date)) + 3)
    WHEN sum(sm_qty) > 2 AND csi.stock_id = 4                       /* history hoppegarten */
        THEN round(avg(DATEDIFF(sm.sm_date, po.po_date)) + 4)
        ELSE cped.value                                             /* default_delivery_time */
    END AS dt_raw


FROM `test_live`.`catalog_product_entity` cpe

LEFT JOIN `test_live`.`cataloginventory_stock_item` csi
ON cpe.entity_id = csi.product_id

LEFT JOIN `test_live`.`catalog_product_entity_decimal` cped     /* default_delivery_time */
ON cpe.entity_id = cped.entity_id
AND cped.attribute_id = 392

LEFT JOIN `test_live`.`catalog_product_entity_decimal` cped2    /* min_qty_delivery_time */
ON cpe.entity_id = cped2.entity_id
AND cped2.attribute_id = 393

LEFT JOIN `test_live`.`stock_movement` sm
ON cpe.entity_id = sm.sm_product_id
AND sm.sm_type = "supply"
AND sm.sm_date > NOW() - Interval 90 DAY

LEFT JOIN `test_live`.`purchase_order` po
ON po.po_num = sm.sm_po_num


WHERE
csi.is_favorite_warehouse = 1
AND (csi.stock_id = 3 OR csi.stock_id = 4)

GROUP BY cpe.entity_id;

SELECT

SELECT CONCAT('ca. ', round(dt_raw), ' weeks') AS delivery_time, 
       IF(dt_raw <= 30, 50, 0) AS amazon_qty
FROM your_schema.dt_raw_temp;

The advantage of using tables is that you can reproduce your calculations at any given moment as long as you keep your tables.

Answer 2

Simply select from your query:

select
  product_id,
  sku,
  dt_raw,
  concat ("ca. ", round(dt_raw), " weeks") as delivery_time,
  case when dt_raw <= 30 then 50 else 0 end as amazon_qty
from
(
  SELECT
    cpe.entity_id AS product_id,
    cpe.sku,
    CASE
      WHEN (csi.qty - csi.stock_ordered_qty) >= cped2.value AND csi.stock_id = 3  /* on stock burgsdorgstrasse */
        THEN 3
      WHEN (csi.qty - csi.stock_ordered_qty) >= cped2.value AND csi.stock_id = 4  /* on stock hoppegarten */
        THEN 7
      WHEN sum(sm.sm_qty) > 2 AND csi.stock_id = 3                                /* history burgsdorfstrasse */
        THEN round(avg(DATEDIFF(sm.sm_date, po.po_date)) + 3)
      WHEN sum(sm.sm_qty) > 2 AND csi.stock_id = 4                                /* history hoppegarten */
        THEN round(avg(DATEDIFF(sm.sm_date, po.po_date)) + 4)
        ELSE cped.value                                                           /* default_delivery_time */
    END AS dt_raw
  FROM test_live.catalog_product_entity cpe
  LEFT JOIN test_live.cataloginventory_stock_item csi ON cpe.entity_id = csi.product_id AND csi.is_favorite_warehouse = 1 AND csi.stock_id in (3,4)
  LEFT JOIN test_live.catalog_product_entity_decimal cped     /* default_delivery_time */ ON cpe.entity_id = cped.entity_id AND cped.attribute_id = 392
  LEFT JOIN test_live.catalog_product_entity_decimal cped2    /* min_qty_delivery_time */ ON cpe.entity_id = cped2.entity_id AND cped2.attribute_id = 393
  LEFT JOIN test_live.stock_movement sm ON cpe.entity_id = sm.sm_product_id AND sm.sm_type = 'supply' AND sm.sm_date > NOW() - Interval 90 DAY
  LEFT JOIN test_live.purchase_order po ON po.po_num = sm.sm_po_num
  GROUP BY cpe.entity_id
) prod;