I am trying to run a query:
INSERT
INTO `ProductState` (`ProductId`, `ChangedOn`, `State`)
SELECT t.`ProductId`, t.`ProcessedOn`, \'Activated\'
FROM `tmpImport` t
LEFT JOIN `Product` p
ON t.`ProductId` = p.`Id`
WHERE p.`Id` IS NULL
ON DUPLICATE KEY UPDATE
`ChangedOn` = VALUES(`ChangedOn`)
(I am not quite sure the query is correct, but it appears to be working), however I am running into the following issue. I am running this query before creating the entry into the 'Products' table and am getting a foreign key constraint problem due to the fact that the entry is not in the Products table yet.
My question is, is there a way to run this query, but wait until the next query (which updates the Product table) before performing the insert portion of the query above? Also to note, if the query is run after the Product entry is created it will no longer see the p.Id as being null and therefore failing so it has to be performed before the Product entry is created.
---> Edit <---
The concept I am trying to achieve is as follows:
For starters I am importing a set of data into a temp table, the Product table is a list of all products that are (or have been in the past) added through the set of data from the temp table. What I need is a separate table that provides a state change to the product as sometimes the product will become unavailable (no longer in the data set provided by the vendor).
The ProductState table is as follows:
CREATE TABLE IF NOT EXISTS `ProductState` (
`ProductId` VARCHAR(32) NOT NULL ,
`ChangedOn` DATE NOT NULL ,
`State` ENUM('Activated','Deactivated') NULL ,
PRIMARY KEY (`ProductId`, `ChangedOn`) ,
INDEX `fk_ProductState_Product` (`ProductId` ASC) ,
CONSTRAINT `fk_ProductState_Product`
FOREIGN KEY (`ProductId` )
REFERENCES `Product` (`Id` )
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB
DEFAULT CHARACTER SET = utf8
COLLATE = utf8_general_ci;
The foreign key is an identifying relationship with the Product table (Product.Id)
Essentially what I am trying to accomplish is this: 1. Anytime a new product (or previously deactivated product) shows up in the vendor data set, the record is created in the ProductState table as 'Activated'. 2. Anytime a product (that is activated), does not show up in the vendor data set, the record is created as 'Deactivated' in the ProductState table.
The purpose of the ProductState table is to track activation and deactivation states of a product. Also the ProductState is a Multi-To-One relationship with the Product Table, and the state of the product will only change once daily, therefore my PKEY would be ProductId and ChangedDate.
With foreign keys, you definitely need to have the data on the Product table first, before entering the state, think about it with this logic: "How can something that dont exist have a state" ?
So pseudocode of what you should do:
All these should be done in 1 transaction. Note that you should NOT delete things from Product table, unless you really want to delete every information associated with it, ie. also delete all the "states" that you have stored.
Rather than trying to do this all in 1 query - best bet is to create a stored procedure that does the work as step-by-step above. I think it gets overly complicated (or in this case, probably impossible) to do all in 1 query.
Edit: Something like this:
CREATE PROCEDURE `some_procedure_name` ()
BEGIN
-- Breakdown the tmpImport table to 2 tables: new and removed
SELECT * INTO _temp_new_products
FROM`tmpImport` t
LEFT JOIN `Product` p
ON t.`ProductId` = p.`Id`
WHERE p.`Id` IS NULL
SELECT * INTO _temp_removed_products
FROM `Product` p
LEFT JOIN `tmpImport` t
ON t.`ProductId` = p.`Id`
WHERE t.`ProductId` IS NULL
-- For each entry in _temp_new_products:
-- 1. Insert into Product table
-- 2. Insert into ProductState table 'activated'
-- For each entry in _temp_removed_products:
-- 1. Insert into ProductState table 'deactivated'
-- drop the temporary tables
DROP TABLE _temp_new_products
DROP TABLE _temp_removed_products
END