I have one table shoutbox_messages with user_id and text.
Now I added some new tables, chats, chat_users and chat_messages.
Now I want to insert the data from chat_messages into the new structure. I created an entry in chat, which needs to be referenced by the chat_users
INSERT INTO chat_users (user_id, chat_id)
SELECT DISTINCT shoutbox_messages.user_id,
(SELECT chats.id FROM chats WHERE chats.shoutbox = true)
FROM shoutbox_messages"
So far so good. Now I want to add all messages from shoutbox_messages to chat_messages
INSERT INTO chat_messages (chat_user_id, text, text_as_html)
SELECT chat_users.id,
(Select shoutbox_messages.text, shoutbox_messages.text_as_html
FROM shoutbox_messages Where shoutbox_messages.user_id =
(SELECT DISTINCT chat_users.id
WHERE chat_users.user_id = shoutbox_messages.user_id
)
)
from chat_users
This is not working, because shoutbox_messages have multiple texts from one user. What do I need to change, to make this work?
The problem you are having is that you are trying to insert multiple columns into one column. as well as not inserting data into the third column, which is presumably not what you want to do.
as seen here: (Select shoutbox_messages.text, shoutbox_messages.text_as_html
FROM shoutbox_messages Where shoutbox_messages.user_id = ... since your inserting data into just the text this query cannot work.
pgsql is interpreting the second query as data for just the text column
You may want to instead of doing the syntax you currently have, use sql join syntax as it would accomplish the same thing
something along the lines of
SELECT chat_users.id, shoutbox_messages.text, shoutbox_messages.text_as_html
FROM chat_users
join shoutbox_messages on shoutbox_messages.id = chat_users.id
just make sure you rewrite my code to the actual code you need to identify each column to the other
Related
I'm quite a novice on this and I don't know if I will explain myself well. I am trying to do an exercise in SQL in which asks me to update the data in an "X" table from other data in a "Y" table. The problem is that it is not about updating table X exactly like the data in table Y. I put the statement and my tables:
Update the "numJocs" field (number of games) for all platforms, depending on the number of games each of the platforms in the GAMES table has.
PLATFORM table:
where: "nom" is name.
GAMES table:
where: "nom" is name, "preu" is price, "idPlataforma" is idPlatform and "codiTenda" is storeCode, but only idPlataforma interested for this exercise.
If I do:
SELECT COUNT(games.idPlataforma)
FROM games
GROUP BY (games.idPlataforma)
I can see how many games there are for each platform. The result would be:
count(games.idPlataforma)
__________________________
2
1
2
2
I would like to be able to put this result in the PLATFORM table, column "numJocs". But I don't know how to do it ... I also don't want to put it manually, that is, a "2" in a row "1", etc ... but I would like to be able to make a query and add that query in the column that I have to fill in. He tried to do a thousand things, but nothing ... Any help?
Thanks!!
for one time update you can use below query
update Product P
INNER JOIN (
SELECT games.idPlataforma, COUNT(games.idPlataforma) as cnt
FROM games
GROUP BY games.idPlataforma
) x ON P.id= x.idPlataforma
SET P.numJocs= x.cnt
For the next time on every entry of new game you have a update numJocs
Suppose you have 2 tables, table 1 and table 2:
Table 1:
Table 2:
You could insert new values into table 1, based on table 2 by doing the following:
insert into Table1(number,CFG) select ITEM,results from Table2
Which has the following result in table 1:
Any database should support the syntax using a correlated subquery:
update platforms
set numjocs = (select count(*)
from games g
where g.idPlatforms = platforms.id
);
I would caution you though about storing this value in the table. It will be immediately out of data if the platforms table changes. If you want to keep it in synch, then you need to create triggers -- and this is all rather complicated.
Rather, calculate the data on the fly:
select p.*,
(select count(*)
from games g
where g.idPlatforms = platforms.id
) as numjocs
from platforms p ;
You can put this in a view if you like. Many databases support materialized views where the results of the view are stored in a "table" and the table is kept up-to-date with the underlying data.
I need to produce some sample SQL for a database to be created with an ERD that I have already made.
The required query is https://imgur.com/vDvL1ZS
and the ERD being used is https://imgur.com/a/hzTQhPU
I've assumed that I need to select from the 3 tables (Message, Chat, UserChat) but I don't understand how the query would be able to match up each instance of messages and users. I've tried to make somewhat of a starting point below but can't see what else would be required.
SELECT MessageID, ChatID, IsText, MessageText, FileName, MessageFile
FROM tbl_Message, tbl_Chat, tbl_UserChat
WHERE tbl_Message.DateSent > UserChat.LastOpened
AND tbl_User.UserID = ‘1044’
AND tbl_Chat.ChatID = ‘139’
A primary key is a field or set of fields which are unique across your table. Each row has its unique primary key.
A foreign key is a field or set of fields, containing only values that are another's table primary key. It is basically a reference to another table.
You can link tables that have references to each others using joins. Here, you are trying to link the Message, Chat and UserChat tables, like so:
select
*
from
UserChat
join
Chat on UserChat.ChatID = Chat.ChatID
join
Message on Chat.ChatID = Message.ChatID
As you can see, I "chained" the joins as the relationships are in the diagram.
Now we got our tables linked, we can add our filters, and only select the Message fields:
select
Message.*
from
UserChat
join
Chat on UserChat.ChatID = Chat.ChatID
join
Message on Chat.ChatID = Message.ChatID
where
UserChat.ChatID = y -- Filter the correct chat
and
UserChat.MessageID = x -- Filter the correct user
and
UserChat.LastOpened < Message.DateSent -- Filter only unread messages
I am trying to make it so all the users have the same items because I am doing an experiment with my app and need the experimental control of flattened data.
I used the following SQL statement in my last attempt:
insert into has (email,id,qty,price,item_info,image)
select 'b#localhost.com',id,qty,price,item_info,image
from
(
select * from has
where email != 'b#localhost.com'
) as o
where o.id not in
(
select id from has
where email = 'b#localhost.com'
);
This should add all items which 'b#localhost.com' does not already have but other users do have, to 'b#localhost.com's inventory. (the 'has' table)
However, I get the following error:
The statement was aborted because it would have caused a duplicate key value in a unique or primary key constraint or unique index
I understand what this error means, but I do not understand why it is occurring. My statement inserts all records which that email doesn't already have, so there should not be any duplicate id/email pairs.
The database structure is shown below, circles are attributes, squares are tables, and diamonds are relationship sets. The HAS table is a relationship set on USER_ACCOUNT and ITEM, where the primary keys are email and id respectively.
Please try the following...
INSERT INTO has ( email,
id,
qty,
price,
item_info,
image )
SELECT a.email,
b.id,
a.qty,
a.price,
a.item_info,
a.image
FROM has a
CROSS JOIN has b
JOIN
(
SELECT email,
id
FROM has
) c ON a.email = c.email AND
b.id <> c.id;
The CROSS JOIN appends a copy of each row of has to each row of has. Please see http://www.w3resource.com/sql/joins/cross-join.php for more information on CROSS JOIN's.
Each row of the resulting dataset will have two id fields, two email fields, two qty fields, etc. By giving each instance of has an alias we create the fields a.id, b.id, a.email, etc.
We then compare each combination of "old" email address and "new" id to a list of existing email / id combinations and insert the old values with the new id replacing the old one into has
If you have any questions or comments, then please feel free to post a Comment accordingly.
Further Reading
http://www.w3resource.com/sql/joins/cross-join.php for more information on CROSS JOIN's
https://www.w3schools.com/sql/sql_in.asp for more information on WHERE's IN operator
https://www.w3schools.com/sql/sql_groupby.asp for more information on GROUP BY
I think the issue here is not that the code is trying to insert something which already exists, but that it's trying to insert more than one thing with the same PK. In lieu of an response to my comment, here is one way to get around the issue:
INSERT INTO has (email,id,qty,price,item_info,image)
SELECT
'b#localhost.com',
source.id,
source.qty,
source.price,
source.item_info,
source.image
FROM
(
SELECT email, id, qyt, price, item_info, image FROM has
) as source
JOIN
(
SELECT min(email) as min_email, id FROM has GROUP BY by id)
) as filter ON
filter.min_email = source.email
WHERE
source.id not in
(
SELECT id from has WHERE email = 'b#localhost.com'
);
The key difference from your original code is my extra join to the subquery I've aliased as filter. This limits you to inserting the has details from a single email per id. There are other ways to do the same, but I figured that this would be a safe bet for being supported by Derby.
I removed the WHERE clause from the source sub-query as that is handled by the final WHERE.
I am aware this has been asked multiple times, but for one reason or another the solutions are not working for me.
Database Layout:
I have Table1 (Scanner_Location) Who is getting data pulled from another table/ subform on a form (Scanner IBOB) * Holds Columns: FP#, Count, Location, Model_ID, PK-SL_ID
Table2 (Scanner Detail) Holds Two of the three data columns: (FP#, Location PK-SN)
Table3 (Scanner_Model) Holds the last data column, displayed in a subform. (PK-Model_ID)
The user will input FP#, and location in one section of the form, then navigate to the subform, and select multiple Models, and enter the count (Textbox). Once Selected, they click an 'update' button that executes my queries. (Of which I have an update, AND an Append Query)
The problem is, just using an update query doesn't add the records. And using an Append query creates duplicates of the existing data.
Here's how the flow carries out:
User selects Model 1 and Model 2 with a count of 4 and an FP# of 100. Clicks update.
The queries update, and the information enters correctly.
User Selects the same models again (Model_Select), with the same FP# and count, the Table1 has the same information entered again, with a different primary key.
The goal:
The append query creates duplicates of existing data. I only want my update and/or append queries to:
Update the existing data - Looking for anything with the same FP#
Add any records that do not exist already (Looking at Model_ID and FP#)
INSERT INTO Scanner_Location ( Model_ID, FootPrints_Num, Location_ID, Scanner_Loc_Cnt )
SELECT Scanner_Model.Model_ID, [Forms]![Scanner_IBOB]![fpNum_txt] AS [FP#],
[Forms]![Scanner_IBOB]![Location_Cbo_main] AS Location,
[Forms]![Scanner_IBOB]![Scanner_Loc_CntTxt] AS [Count]
FROM Scanner_Detail
RIGHT JOIN Scanner_Model ON Scanner_Detail.Model_ID = Scanner_Model.Model_ID
WHERE (((Scanner_Model.SM_Acc_Select)=True)
AND ((NOT Exists (SELECT * FROM Scanner_location
WHERE (((Forms!Scanner_IBOB!fpNum_txt)=Forms!Scanner_IBOB!fpNum_txt)
And ((Scanner_Model.SM_Acc_Select)=True)); ))=False));
No query named 'Update_SLoc_Acc53' - there are 'Update_SLoc_Acc3' and 'Update_SLoc_Acc54'. I modified 'Update_SLoc_Acc54' because it is the one called by the code.
The query was not pulling the Location_ID from the combobox. I found the Bound Column was set to 1 and should be 0 to reference the Location_ID column because column index begins with 0. Can hide this column from user by setting width to 0.
This query seems to work:
INSERT INTO Scanner_Location ( Model_ID, FootPrints_Num, Location_ID, Scanner_Loc_Cnt )
SELECT Scanner_Model.Model_ID, [Forms]![Scanner_IBOB]![fpNum_txt] AS FPNum,
[Forms]![Scanner_IBOB]![Location_Cbo_main] AS Location,
[Forms]![Scanner_IBOB]![Scanner_Loc_CntTxt] AS CountMod
FROM Scanner_Model
WHERE (((Scanner_Model.SM_Acc_Select)<>False)
AND (([Model_ID] & [Forms]![Scanner_IBOB]![fpNum_txt] &
[Forms]![Scanner_IBOB]![Location_Cbo_main])
NOT IN (SELECT Model_ID & Footprints_Num & Location_ID FROM Scanner_Location)));
Note I did not use # in field name. Advise not to use punctuation/special characters in names with only exception of underscore. Also used CountMod instead of Count as field name.
Why the requirement to select two models? What if one is added and the other isn't?
I have concerns about the db structure.
Don't think App_Location and App_Detail should both be linking to other tables. Why is Location_ID the primary key in App_Location as well as primary key in Location_Data? This is a 1-to-1 relationship.
Is Serial_Number the serial number for scanner? Why is it a primary key in Telnet? This also results in a 1-to-1 relationship in which case might as well combine them.
If an app is associated with a scanner and scanner is associated with a location then don't need location associated with app. Same goes for scanner and telnet.
Scanner_Location table is not linked to anything. If purpose of this table is to track a count of models/footprints/locations -- as already advised this is usually not a good idea. Ideally, count data should be calculated by aggregate query of raw data records when the information is needed.
Maybe use NOT IN, something like:
[some identifier field] NOT IN (SELECT [some identifier field] FROM
Review EXISTS vs IN
Consider following adjusted append query that checks existence of matched Model_ID and FP_Num in Scanner_Location. If matches do not exist, then query imports selected records as they would be new records and not duplicates. Also, table aliases are used for readability and subquery correlation.
INSERT INTO Scanner_Location ( Model_ID, FootPrints_Num, Location_ID, Scanner_Loc_Cnt )
SELECT m.Model_ID, [Forms]![Scanner_IBOB]![fpNum_txt] AS [FP#],
[Forms]![Scanner_IBOB]![Location_Cbo_main] AS Location,
[Forms]![Scanner_IBOB]![Scanner_Loc_CntTxt] AS [Count]
FROM Scanner_Detail d
RIGHT JOIN Scanner_Model m ON d.Model_ID = m.Model_ID
WHERE ((m.SM_Acc_Select = True)
AND (NOT EXISTS (SELECT 1 FROM Scanner_Location loc
WHERE ((loc.FootPrints_Num = Forms!Scanner_IBOB!fpNum_txt)
AND (loc.Model_ID = m.Model_ID)) ) ));
Downloads table:
id (primary key)
user_id
item_id
created_at
updated_at
The user_id and item_id in this case are both incorrect, however, they're properly stored in the users and items table, respectively (import_id for in each table). Here's what I'm trying to script:
downloads.each do |download|
user = User.find_by_import_id(download.user_id)
item = item.find_by_import_id(download.item_id)
if user && item
download.update_attributes(:user_id => user.id, :item.id => item.id)
end
end
So,
look up the user and item based on
their respective "import_id"'s. Then
update those values in the download record
This takes forever with a ton of rows. Anyway to do this in SQL?
If I understand you correctly, you simply need to add two sub-querys in your SELECT statement to lookup the correct IDs. For example:
SELECT id,
(SELECT correct_id FROM User WHERE import_id=user_id) AS UserID,
(SELECT correct_id FROM Item WHERE import_id=item_id) AS ItemID,
created_at,
updated_at
FROM Downloads
This will translate your incorrect user_ids to whatever ID you want to come from the User table and it will do the same for your item_ids. The information coming from SQL will now be correct.
If, however, you want to update the tables with the correct information, you could write this like so:
UPDATE Downloads
SET user_id = User.user_id,
item_id = Item.item_id
FROM Downloads
INNER JOIN User ON Downloads.user_id = User.import_id
INNER JOIN Item ON Downloads.item_id = Item.import_id
WHERE ...
Make sure to put something in the WHERE clause so you don't update every record in the Downloads table (unless that is the plan). I rewrote the above statement to be a bit more optimized since the original version had two SELECT statements per row, which is a bit intense.
Edit:
Since this is PostgreSQL, you can't have the table name in both the UPDATE and the FROM section. Instead, the tables in the FROM section are joined to the table being updated. Here is a quote about this from the PostgreSQL website:
When a FROM clause is present, what essentially happens is that the target table is joined to the tables mentioned in the fromlist, and each output row of the join represents an update operation for the target table. When using FROM you should ensure that the join produces at most one output row for each row to be modified. In other words, a target row shouldn't join to more than one row from the other table(s). If it does, then only one of the join rows will be used to update the target row, but which one will be used is not readily predictable.
http://www.postgresql.org/docs/8.1/static/sql-update.html
With this in mind, here is an example that I think should work (can't test it, sorry):
UPDATE Downloads
SET user_id = User.user_id,
item_id = Item.item_id
FROM User, Item
WHERE Downloads.user_id = User.import_id AND
Downloads.item_id = Item.import_id
That is the basic idea. Don't forget you will still need to add extra criteria to the WHERE section to limit the rows that are updated.
i'm totally guessing from your question, but you have some kind of lookup table that will match an import user_id with the real user_id, and similarly from items. i.e. the assumption is your line of code:
User.find_by_import_id(download.user_id)
hits the database to do the lookup. the import_users / import_items tables are just the names i've given to the lookup tables to do this.
UPDATE downloads
SET downloads.user_id = users.user_id
, downloads.item_id = items.items_id
FROM downloads
INNER JOIN import_users ON downloads.user_id = import_users.import_user_id
INNER JOIN import_items ON downloads.item_id = import_items.import_item_id
Either way (lookup is in DB, or it's derived from code), would it not just be easier to insert the information correctly in the first place? this would mean you can't have any FK's on your table since sometimes they point to one table, and others they point to another. seems a bit odd.