(MySQL) I am trying to migrate a "subscription" table into 3 new tables: "product", "subscription", "actual" where "actual" is the name of the actual product, say, newsletter. The subscription has a FK reference to product and the actual has FK reference into subscription.
I know the INSERT INTO SELECT statement can copy data probably from many table to one; is there a statement to do the opposite, one to many tables for my case?
I'm not aware of an SQL statement that will do what you want. Just do several INSERT INTO SELECTs one after the other. It may be faster to do them one at a time anyway.
I think you can use three seperate insert into select statements. First you convert the product table, then the subscription where you can use an embedded select to find the id in the product table:
insert into subscription (some_column, FK_id,...)
select something, (select id from product where <your where clause>),...
and finally convert the actual table using an embedded select to get the id from the subscription table.
Related
I have a table called: Orders (Id, FK_Customer_Id, Comments, PaymentMethod, DeliverTime), which is used to store order information of a online retailer website, and also a table: Order_Items (Id, FK_Order_Id, FK_Product_Id, Quantity), to store the details of an order.
once the user submit an order, I need to save the information to the two table, but I don't know how to solve the concurrency problem.
Because, I should first insert into Orders table, then get the Order_Id and insert this Id to Order_Items table. I try to use "SELECT LAST_INSERT_ID() AS OrderId". But what if I insert into order and before I can get the Id, someone else insert another Order? Then the above statement will get the Id of the new inserted order, which is not my order anymore.
Please help me and let me know how to do it, or if I design the order/orderItem in a wrong way.
P.S. I m using angular 2 as front-end and node.js to create APIs and MySQL as DB.
Thank you in advance.
I would separate the operations.
This will prevent any unexpected "race" affects with inserting records.
So, first, insert the order.
Then, second, confirm that the insert query was successful by asking for the "insert id" with something like mysql_insert_id() or whatever the node.js equivalent is.
Then, third, once you have that id, you can safely insert the details of the order.
I have a table (People) with columns (id, name, year). Is there any way I can get all the ids ( SELECT id FROM people ) and use them for creating new rows in other table (people_id, additional_info). I mean that for every id in table People I want to add new row in other table containing the id and some additional information. Maybe something like for-loop is needed here ?
Well, usually you have information on a person and write one record with this information. It makes litte sense to write empty records for all persons. Moreover, when it's just one record per person, why not simply add an information column to the people table?
Anyway, you can create mock records thus:
insert into people_info (people_id, additional_info)
select id, null from people;
Insert into targetTable (id, additional_info)
select id,'additionalinfo' from PEOPLE
No for loop is needed, Just use the above query.
You can use INSERT ... SELECT syntax for MySQL to insert the rows into people_info table (documentation here).
e.g.
insert into people_info(...)
select (...) from people; <and posibly other tables>
I just was wondering if is it possible to associate an user to the data inserted in a table.
For example:
I have a table Customers with columns customerID, name and address. Is there any method in MySql to know what user has inserted each row in the table or must I add a column userID in the table Customer to add the user in my SQL Insert statement?.
If I have only one table, it is not a proble to add the userID column. But when i have multiple tables, maybe it becomes a messy task.
Thanx in advance.
If you are trying to find out the user_id caused the insert then NO, there is no other way than you storing it explicitly likewise you already have thought of.
If there is multiple tables for which you want to store the same information; then you can probably have a separate table where you can have the user_id column and can use a AFTER INSERT TRIGGER to insert the user id in this table.
No, no such functionality is provided by MySQL. You'll have to add a column for user_id in your table(s) and insert the user id yourself.
I have a MySql table called Person, and one day I accidentally deleted someone from this table. I have a backup table, called PersonBak so I was going to restore my deletion from the backup. However, in the course of moving forward on my application I renamed all the fields in Person, except for the primary key, PersonID. Now Person and PersonBak have the same data, but only one matching column name.
Is there any way to restore my missing person to Person from PersonBak without doing a lot of work? I have quite a few columns. Of course I could just do the work now, but I can imagine this coming up again.
Is there some way to tell MySql that these are really the same table, with the columns in the same order, just different column names? Or any way at all to do this without writing out specifics of which columns in PersonBak match which ones in Person?
If the column datatypes are the same between the tables, the column count is the same, and they are all in the same order, then MySQL will do all of the work for you:
INSERT INTO t1 SELECT * FROM t2;
The column names are ignored. The server uses ordinal position only, to decide how to line up the from/to columns.
What about this:
insert into Person(id, col11, col12) (select id, col21, col22 from personBak where id=5)
person schema:
columns (id, col11, col12)
personBak schema:
columns (id, col21, col22)
Look at Mysql SELECT INTO and you can specify the field names & create an insert statement
I have two tables:
Table1 - Sales
id, Timestamp, Notes, CSR, Date, ExistingCustomer, PubCode, Price, Pub, Expiry, Size, KeyCode, UpSell, CustName, CustAddress, CustCity, CustState, CustPostal, CustCountry, CustPhone, CustEmail, CustCardName, CustCardNumber, CustCardType, CustCardExpiry, CustCardCode
Table2 - Refunds
id,Timestamp,CSR,Date,OrderId,Refunded,Saved,Publication
Basically, I want to create a table (MySQL) which will have some columns that are the same between the two tables and which will update automatically with the values from these two columns.
ie. Table3
Timestamp, CSR, Date, Publication
And this table would automatically update whenever a new record is posted into either of the other two tables, so it would essentially be a merged table.
Because there's nothing to join these two tables, I don't think the JOIN function would work here. Is there anyway I can do this?
You can use an trigger which actives on insert on both tables to make it automatically update.
As for combining tables with no common tables, view this question.
You need to use a stored procedure and a trigger on insert/update of the non merged table
There's got to be some way to join it, and in fact you mention Timestamp, CSR, Date, Publication.
You could join on them in a view. You could add table three and then add triggers though that would be an awful mess.
Why do you want to denormalise in this way?
How about Table3 is a unique key to use as a surrogate, and your 4 join fields, and then you take those out of Table 1 and 2 and replace them with the key the suurrogate key in table 3.
Then it'sa simple join query and no data duplication.