As you save from the image, I have a Packing and a Product table. I want to somehow connect some rows from the product table to the Productlist column of Packing table, so that in future I can add packing in the database and write also what products I have in this packing. How can I achieve this?
If Product List has multiple values in it you should not store them in a single column in the table. You should create a separate table that has PackingTableID and Product so in this new table you would have multiple Products tied to one Package. Then you would join to that table. (a one to many relationship).
Similar to this:
Select PackingTable.PackingTableID , ProductTable.PackageName
From PackingTable
INNER JOIN PackingTableProducts ON PackingTable.PackingTableID = PackingTableProducts.PackingTableID
INNER JOIN ProductTable ON PackingTableProducts.ProductID = ProductTable.ProductID
Related
I working on groups project. I have those tables :
I can get the number of members for each group by using count function :
SELECT COUNT(1) AS Counts FROM [Groups].[GroupMembers]
WHERE GroupId=Id;
Or I can add another column to Groups table for counting and every time new member join to the group, this field will increase by one. Does it better to use count function or add another column for counting ? in other words, what are the advantages and disadvantages of each method ?
Creating a column to store the count's is not recommend at all.
When you want the count of each group you can use a simple Select query to show the count of each group.
SELECT G.groupid,
Count(userid)
FROM groups G
LEFT OUTER JOIN groupmembers GM
ON G.groupid = GM.groupid
GROUP BY G.groupid
In case you want to add a new column then you will require a Trigger on GroupMembers table to update the count column in Groups table when a new user is added to any group in GroupMembers table
It depends on your table engine. If your table engine is MyISAM it would be much faster because it would simply read number of rows in the table from stored value, however Innodb engines will need to do a full table scan.
It is not recommended to store a count inside of the table itself, so if this is something you're worried about, use the MyISAM engine if possible.
Storing a value in the table would needlessly require an extra UPDATE query on each new/lost membership.
How can i transfer rows from two tables (Patient and ContactDetails) from DB1 to DB2?
Both DBs, have already these 2 tables with data. i just want to add data from these two tables from db1 to db2.
i tried following that
but it didnt work, because there are some rows with the same keys and overwrite is forbidden.
is there an other way to do it? or am i missing something?
patient and contactdetails relationship is
patient inner join contactdetails
(foreign_key)patient.contactdetailsid = (primary_key)contactdetails.id
loop on the source contactdetails table, insert each row one a time saving in a temp table the old contactdetail id and the matching new contactdetail id (here is an example of sql loop).
the temp table should be something like:
create #temptableforcopy table (
oldcontactdetailsid [insertheretherightdatatype],
newcontactdetailsid [insertheretherightdatatype]
)
copy the data from the patient table joined to the temp table used for the previous step like this:
insert into newdb.newschema.patient (contactdetailsid, field1, field2, ...)
select TT.newcontactdetailsid,
old.field1,
old.field2,
...
from olddb.oldschema.patient old
join #temptableforcopy TT on TT.oldcontactdetailsid = old.contactdetailsid
please note that my proposal is just a wild guess: you gave no information about structure, keys, constraints, no detail about which key is preventing the copy with which error message, the solution you already discarded, the amount of data you have to deal with...
I have the following DB Tables with SQL Server
Booking(bookingID,customerName,branchID,RefNumber,...)
Trip(TripID,vehicleID,...)
BookingToTripMap(TripID,bookingID)
Branch(branchID, branchName)
Vehicle(vehicleID,vehicleNumber)
There is a one to one relationship between (Booking,Branch) and (Trip, Vehicle) and Many to many relationship between Booking, Trip which is saved in the table BookingToTripMap.
Now I want to extract a query that would return the following
Booking.RefNumber Booking.CustomerName Vehicle.VehicleNumber
(All vehicle numbers in one cell)
Here is your query
SELECT B.RefNumber, B.CustomerName, V.VehicleNumber
FROM ((Booking AS B INNER JOIN BookingToTripMap AS BT
ON B.bookingID = BT.bookingID) INNER JOIN TRIP as T
ON T.TripID = BT.TripID) INNER JOIN Vehicle as V
ON V.vehicleID = T.vehicleID
I would add the field bookingID to the table Trip, it seems that the table BookingToTripMap doesn't add any value to your database.
Also, if your vehicle's numbers are unique, you could change the primary key in the Vehicle table to vehicleNumber, and change the same columns in the Trip table. Thus you could retrieve the vehicleNumber directly from the Trip table.
I'm just guessing in that, based on the given information.
Regards,
I need to create a new table called “customer” that include some of columns from the “user table”, and also “project table”. I built my suppliers table with specific column names and I need to fill its column by using data of the other tables. Finally I am trying to finish; when user create a new account and project, the customer table automatically fill with some of other two tables varieties with different column names.
INFO: I have three different user types such as “suppliers”, “costumers”, “managers”. I am holding their information(include user types) in one table called users.
Use the following query as an example and write a query to insert the rows to destination table from source table.
Ex:-
INSERT INTO TestTable (FirstName, LastName)
SELECT FirstName, LastName
FROM Person.Contact
WHERE EmailPromotion = 2
Note: Use Join in the select query to join two tables
The 1st step would be to couple the data from the different tables using a table join command. If you can create a search result that matched your new table, then creating the table is simple a call to the below.
Create table CUSTOMER as (Select ...)
"when user create a new account and project.." this is something you plan on doing at run time in your application and not something you need to collate using sql at this point?
Web app is being written in classic ASP with a MSSQL backend. On this particular page, the admin can select 1 or any/all of the employees to assign the project to. I'm trying to figure out a simple way to store the employee IDs of the people assigned to it in one column.
The list of employees is generated from another table and can be dynamic (firing or hiring) so I want the program to be flexible enough to change based on these table changes.
Basically need to know how to assign multiple people to a project that can later be called up on a differen page or from a different query.
Sorry for the n00bish question, but thanks!
Don't store multiple ID's in one column! Create another table with the primary key of your existing table and a single ID that you want to store. You can then insert multiple rows into this new table, creating a 1:m (one to many) relationship. For example, let's look at an order table:
order:
order_id
order_date
and I have a product table...
product:
product_id
product_name
Now, you could go down the road of adding a column to order that let you list the products in the order, but that would be bad form. What you want instead is something like..
order_item:
order_item_id
order_id
product_id
quantity
unit_price
You can then perform a join to get all of the products for a particular order...
select
product.*
from orders
inner join order_item on order_item.order_id = order.order_id
inner join product on product.product_id = order_item.product_id
where orders.order_id = 5
Here's an example order_id of 5, and this will get all of the products in that order.
You need to create another table that stores these values such as. So this new table would store one row for each ID, and then link back to the original record with the original records ID.