Hello I am not able to create view for following query.
create view my_View as
select * from product p
LEFT JOIN product_description pd ON (p.product_id=pd.product_id)
I have two tables
TABLE1 :-
Product with column as :- product_id, column2,column3
TABLE2 :- Product_Description with column as:- product_id , column4,column5.
Here product_id is foreign key for Product table.
Following is the error I am getting
Error Code: 1060. Duplicate column name 'product_id'
I am using mysql workbench to run my queries. Looking at the error, I understand that I need to assign alias. But I am required to join more than 5-8 tables thats the reason I am looking for better solution.
The Error is coming due to same column name in both the tables, second thing is its never a good practice to fetch all records in views by using * until and unless you really want all records from all table that you are using in join condition.
What you can do is select records specific to your view, like
select p.*,pd.somefield from product p
LEFT JOIN product_description pd ON (p.product_id=pd.product_id)
In the above query your product_id is fetched from product table only and you can fetch only necessary fields from product_description table
The easiest solution in your case is to use using instead of on:
create view my_View as
select *
from product p LEFT JOIN
product_description pd
USING (product_id);
In general, though, you should list the columns explicitly in the select rather than using *.
SELECT * will select all columns from both tables in the join. But both tables have a column called product_id, so you'll get two columns in the view with the same name.
You need to list out all the columns, so you can give an alias to product_description.product_id to distinguish it:
SELECT p.product_id, p.column2, p.column3, pd.product_id AS pd_id, pd.column4, pd.column5
FROM product AS p
LEFT JOIN product_description AS pd ON p.product_id = pd.product_id
Related
I want to select multiple fields from table p.
The second line of this code is wrong. how to write?
except p.*
I don't want p.*
SELECT
p.id, title, price
c.`title` as `CategoryTitle`
from `tbl_products` p
INNER JOIN `tbl_categories` c
ON p.`category_FK` = c.`id`
Well, you might have your own reason so, perhaps you can do something like this:
SELECT
id, title, price, CategoryTitle
FROM `tbl_products` p
INNER JOIN
(SELECT `title` AS 'CategoryTitle', id AS 'CategoryID'
FROM `tbl_categories`) c
ON category_FK = CategoryID
Make one of the table as a subquery and define column alias that's not a duplicate with the other table. In your example, it seems like both of your tables have columns with similar names like id & title. Once you define those similar column names in the subquery with different alias, then you won't need to do p.xx or c.xx.
I have a table "product_quantity_cart" that has a "price" column in Mysql. I want to update all rows that match certain "id" with the result of a select that uses values from two different tables. In order to do so, I am executing a select subquery inside the update and as a result I am getting error 1224: "subquery returns multiple rows". I have read that a subquery like mine is not the right way to achieve what I want in Mysql, so I would like to ask which is the proper way to do it.
My query looks like so:
update product_quantity_cart set price_product =
(
select quantity*price from (select * from product_quantity_cart) as p_q_c inner join product
on product.id_product=p_q_c.id_product
where id_shopping_cart=7
);
'''
As you can see, I intend to update column price_product in all rows from table product_quantity_cart.
I don't know what your tables looks like but I'm just assuming that the product in your inner join product (given above) is your table2 with columns p.id_product and p.quantity and your product_quantity_cart has columns id_product, price_product, c.price, and c.id_shopping_cart
Then the query could be like this;
update product_quantity_cart c JOIN product p ON p.id_product = c.id_product
set c.price_product = c.price * p.quantity
WHERE c.id_shopping_cart=7
I'm creating a product filter for e-commerce store. I have a product table, characteristics table and a table in which I store product_id, characteristic_id and a single filter value.
shop_products - id, name
shop_characteristics - id, values (json)
shop_values - product_id, characteristic_id, value
I can build a query to get all the products by a single value like this:
SELECT `p`.* FROM `shop_products` `p`
LEFT JOIN `shop_values` `fv` ON `p`.`id` = `fv`.`product_id`
WHERE ((`fv`.`characteristic_id`=3) AND (`fv`.`value`='outdoor'))
It works fine. Also, I can modify this query and get all the products by multiple values that belong to the very same characteristics group (have identical characteristics_id) like this:
SELECT `p`.* FROM `shop_products` `p`
LEFT JOIN `shop_values` `fv` ON `p`.`id` = `fv`.`product_id`
WHERE ((`fv`.`characteristic_id`=3) AND (`fv`.`value`='outdoor'))
OR ((`fv`.`characteristic_id`=3) AND (`fv`.`value`='indoor'))
but when I try to create a query for multiple conditions with different characteristic_id I get nothing
SELECT `p`.* FROM `shop_products` `p`
LEFT JOIN `shop_values` `fv` ON `p`.`id` = `fv`.`product_id`
WHERE ((`fv`.`characteristic_id`=3) AND (`fv`.`value`='outdoor'))
AND ((`fv`.`characteristic_id`=5) AND (`fv`.`value`='white'))
My guess it does not work because of AND operator that I am using wrong in this case due to there are no records in shop_values table that have both characteristic_id 3 and 5.
So my question is how to combine or modify my query to get all related products or maybe it is a flaw to store data like this and I need to create a different kind of shop_values table?
Use aggregation. You can also use tuples with the in clause. So:
SELECT p.*
FROM shop_products p JOIN
shop_values v
ON p.id = v.product_id
WHERE (v.characteristic_id, v.value) IN ( (3, 'outdoor'), (5, 'white'))
GROUP BY p.id
HAVING COUNT(DISTINCT v.characteristic_id) = 2;
Notes:
Unnecessarily escaping column and table aliases (with backticks) just makes the query harder to write and to read.
In general, using SELECT p.* and GROUP BY p.id is really, really bad form. The one exception is when you are grouping by a unique or primary key. This latter form is actually supported in the ANSI standard.
A LEFT JOIN is not needed. You need to find matches between the tables for the logic to work.
The use of AND and OR is fine for the WHERE clause. MySQL happens to support tuples with IN, which somewhat simplifies the logic.
I have two table in the PostgreSQL DB which looks like
Select Productid,productname,quantity,availabilty from public.product
And other table is
Select sampleid,samplename,Productid from public.sample
So here I need to select the Products and their sample from the product table and sample table where Productid in the Product table is equal to the productid in the sample table. Should I be using the Joins here.I am confused with the Left and right join
I need to select the Products and their sample
I think you can use LEFT JOIN here to get all products and matching samples if any:
select p.*,
s.sampleid,
s.samplename
from public.product p
left join public.sample s on s.Productid = p.Productid;
I'm trying to read all the SKU numbers from my product table and add those as tags into my product description table.
Here is the query I'm using:
INSERT INTO product_description (tag)
SELECT sku
FROM product p
WHERE p.product_id = pd.product_id; #I don't know where to define pd
Neither of these work:
INSERT INTO product_description pd (tag)
INSERT INTO product_description (tag) pd
I'm having difficulty figuring out how the WHERE clause should be constructed. I need to make sure the product IDs match from both tables and I can't give the first table an alias either.
To clarify my question, I'm actually trying to update my existing data in the product_description table, I'm not trying to add/insert new rows.
I believe you are looking for an update query here, as you are setting the value in one table based on it's relation to another.
To do this, you can JOIN the tables together using the related column, and set the values accordingly:
UPDATE product_description pd
JOIN product p ON p.product_id = pd.product_id
SET pd.tag = p.sku;
Here is an SQL Fiddle example.
INSERT INTO product_description (tag)
(SELECT sku
FROM product p
INNER JOIN product_description pd ON p.product_id = pd.product_id
I'm trying to read all the SKU numbers from my product table and add
those as tags into my product description table.
I read this as wanting something like this:
INSERT INTO product_description (tag)
SELECT distinct sku
FROM product p;
If you don't want duplicates, then be sure that you have a unique index/constraint on product_description(tag).
You don't give the structure of the table, but you might want the product id along with the tag:
INSERT INTO product_description (product_id, tag)
SELECT product_id, sku
FROM product p;