So first sorry for my english, my native language is german.
I have an ACCESS DB with a few Tables, the DB is filled with healing Plants, and there is one Table named "Issues" it looks like that:
Columns: ID -- Name -- Headache -- Pain -- Vomitting - and so on....
And the Columns for the indications like headache and so on, are boolean- True or False.
Now i`d like to make an query that asks the user (With a listbox in a form or so, or a Text input) to tell his indication, and then there should be a list of Substances/Plants where the Value for the indication (ColumnName) is true.
I think thats a parameter for a search in a table for columns.
I'd look at the design of your database. Having a table with separate columns for each issue would be a real headache to update if another issue became apparent.
I'd probably use four tables for this:
Users: UserID (AutoNum, PK), UserName (Text)
Plants: PlantID (AutoNum, PK), PlantName (Text)
IssueList: IssueID (AutoNum, PK), IssueDescription (Text)
User_Issues: UserID (Num, PK), PlantID (Num, PK), IssueID (Num, PK), HasIssue (Boolean)
The User_Issues table has a composite key made up each identifier from the other tables - this will ensure that a user can't have the same issue for a plant more than once.
When a new user is created a query runs to update the User_Issues table:
INSERT INTO User_Issue(PlantID, IssueID, UserID)
SELECT PlantID, IssueID, UserID
FROM Plants, IssueList, Users
WHERE UserName = "Darren"
This will create a Cartesian product from the plants and issues for each user. So, for example, if you have two plants and three issues you'll get 2x3 records created - a possible 6 issues across the two plants.
This SQL will allow you to allocate an issue:
SELECT UserName
, PlantName
, IssueDesc
, HasIssue
FROM ((
User_Issue INNER JOIN Users ON User_Issue.UserID = Users.UserID)
INNER JOIN Plants ON User_Issue.PlantID = Plants.PlantID)
INNER JOIN IssueList ON User_Issue.IssueID = IssueList.IssueID
ORDER BY PlantName, IssueDesc
To view the issues you just have to add WHERE HasIssue to the above SQL.
SELECT UserName
, PlantName
, IssueDesc
, HasIssue
FROM ((
User_Issue INNER JOIN Users ON User_Issue.UserID = Users.UserID)
INNER JOIN Plants ON User_Issue.PlantID = Plants.PlantID)
INNER JOIN IssueList ON User_Issue.IssueID = IssueList.IssueID
WHERE HasIssue
ORDER BY PlantName, IssueDesc
Related
i have two tables
details like below
user master
----------------
userid int (pk)
username
useraddress
user transactions
-----------------
fromUser int (fk - userid)
toUser int (fk - userid)
amount
i need to display data as follows
fromUsername
toUsername
amount
i tried many queries but i am unable to form a proper select query
tried googling and much more but due to lack of searching with proper keyword i am unable to find the desired answer
You just need two joins:
select mf.username, mt.username, t.amount
from transactions t join
master mf
on t.fromUser = mf.userId join
master mt
on t.toUser = mt.userId;
If either user could be NULL or invalid, use left join instead of join.
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 have a very simple MS Access User Table (USER_TABLE) consisting of 3 fields: Customer_Number, User_Name, and Email_Address. I have another table (NEW_USERS) that consist of new requests for Users. It has a User_Status field that is blank by default, and also has the Customer_Number, User_Name, and Email_Address fields.
Half of the new requests that come through are users already existing, so I want to set up a query that will check the USER_TABLE to determine if a new request exists or not, using the Email_Address field checked vs. the Customer_Number field. Complicating this is the fact that 1) Customer_Number is not unique (many Users exists for a single Customer Number) and 2) Users can have multiple accounts for different Customer Numbers. This results in 4 scenarios in the NEW_USERS table when checking vs. the USER_TABLE:
Email_Address does not exist for Customer Number in USER_TABLE (New)
Email_Address exists for Customer Number in USER_TABLE (Existing)
Email_Address does not exist for Customer Number in USER_TABLE, but exists for other Customer Numbers (New-Multi)
Email_Address does exist for Customer Number in USER_TABLE, and also exists for other Customer Numbers (Existing-Multi)
What I would like to do is run these checks and enter the corresponding result (New, Existing, New-Multi or Existing-Multi) into the User_Status field.
This seems like it would be possible. Is it possible to run 4 separate queries to make the updates to NEW_USERS.User_Status?
When you're working in Access, you really need a field that uniquely identifies each record. At the very least, some combination of field, like customerid and email.
Beyond that, since you have a few criteria to satisfy, the easiest way is probably to make a single select statement that compares data between the results of multiple select statements. Look into outer joins for picking the results from one table that are not found in another. Something like -
insert into user_table select customerid, email_address from
(select customerid, email_address from new_users inner join user_table on ...) as expr1,
(select customerid, email_address from new_users outer join user_table on ...) as expr2
where expr1.customerid = expr2.customerid and expr1.new_users = expr2.new_users
I recommend trying out the free stanford course on sql, theres a handy lesson on nesting your select statements - its a good way to get results that fit a lot of criteria. http://class2go.stanford.edu/
As an aside, they do a lot using syntax of 'specifying joins in the where claus' which is increasingly frowned upon, but much easier to understand.
The query I am trying to perform is
With getusers As
(Select userID from userprofspecinst_v where institutionID IN
(select institutionID, professionID from userprofspecinst_v where userID=#UserID)
and professionID IN
(select institutionID, professionID from userprofspecinst_v where userID=#UserID))
select username from user where userID IN (select userID from getusers)
Here's what I'm trying to do. Given a userID and a view which contains the userID and the ID of their institution and profession, I want to get the list of other userID's who also have the same institutionID and and professionID. Then with that list of userIDs I want to get the usernames that correspond to each userID from another table (user). The error I am getting when I try to create the procedure is, "Only one expression can be specified in the select list when the subquery is not introduced with EXISTS.". Am I taking the correct approach to how I should build this query?
The following query should do what you want to do:
SELECT u.username
FROM user AS u
INNER JOIN userprofspecinst_v AS up ON u.userID = up.userID
INNER JOIN (SELECT institutionID, professionID FROM userprofspecinst_v
WHERE userID = #userID) AS ProInsts
ON (up.institutionID = ProInsts.institutionID
AND up.professionID = ProInsts.professionID)
Effectively the crucial part is the last INNER JOIN statement - this creates a table constituting the insitutionsids and professsionids the user id belongs to. We then get all matching items in the view with the same institution id and profession id (the ON condition) and then link these back to the user table on the corresponding userids (the first JOIN).
You can either run this for each user id you are interested in, or JOIN onto the result of a query (your getusers) (it depends on what database engine you are running).
If you aren't familiar with JOIN's, Jeff Atwood's introductory post is a good starting place.
The JOIN statement effectively allows you to explot the logical links between your tables - the userId, institutionID and professionID are all examples of candidates for foreign keys - so, rather than having to constantly subquery each table and piece the results together, you can link all the tables together and filter down to the rows you want. It's usually a cleaner, more maintainable approach (although that is opinion).
I use three tables to get to the final result. They are called project_board_members, users and project_team.
This is the query:
SELECT `project_board_members`.`member_id`,
`users`.`name`,
`users`.`surname`,
`users`.`country`,
`project_team`.`tasks_completed`
FROM `project_board_members`
JOIN `users`
ON (`users`.`id` = `project_board_members`.`member_id`)
JOIN `project_team`
ON (`project_team`.`user_id` = `project_board_members`.`member_id`)
WHERE `project_board_members`.`project_id` = '5'
You can ignore last line because it just points to the project I'm using.
Table project_board_members holds three entries and have structure like:
id,
member_id,
project_id,
created_at;
I need to get member_id from that table. Then I join to users table to get name, surname and country. No problems. All works! :)
After that, I needed to get tasks_completed for each user. That is stored in project_team table. The big unexpected thing is that I got four entries returned and the big what-the-f*ck is that in the project_board_members table are only three entries.
Why is that so? Thanks in advice!
A SQL join creates a result set that contains one row for each combination of the left and right tables that matches the join conditions. Without seeing the data or a little more information it's hard to say what exactly is wrong from what you expect, but I'm guessing it's one of the following:
1) You have two entries in project_team with the same user_id.
2) Your entries in project_team store both user_id and project_id and you need to be joining on both of them rather than just user_id.
The table project_board_members represent what is called in the Entity-Relationship modelling world an "associative entity". It exists to implement a many-to-many relationship (in this case, between the project and user entities. As such it is a dependent entity, which is to say that the existence of an instance of it is predicated on the existence of an instance of each of the entities to which it refers (a user and a project).
As a result, the columnns comprising the foreign keys relating to those entities (member_id and project_id) must be form part or all of the primary key.
Normally, instances of an associative entity are unique WRT the entities to which it relates. In your case the relationship definitions would be:
Each user is seated on the board of 0-to-many projects;
Each project's board is comprise of 0-to-many users
which is to say that a particular user may not be on the board of a particular project more than once. The only reason for adding other columns (such as your id column) to the primary key would be if the user:project relationship is non-unique.
To enforce this rule -- a user may sit on the board a particular project just once -- the table schema should look like this:
create table project_board_member
(
member_id int not null foreign key references user ( user_id ) ,
project_Id int not null foreign key references project ( project_id ) ,
created_at ...
...
primary key ( member_id , project_id ) ,
)
}
The id column is superfluous.
For debugging purposes do
SELECT GROUP_CONCAT(pbm.member_id) AS member_ids,
GROUP_CONCAT(u.name) as names,
GROUP_CONCAT(u.surname) as surnames,
GROUP_CONCAT(u.country) as countries,
GROUP_CONCAT(pt.tasks_completed) as tasks
FROM project_board_members pbm
JOIN users u
ON (u.id = pbm.member_id)
JOIN project_team pt
ON (pt.user_id = pbm.member_id)
WHERE pbm.project_id = '5'
GROUP BY pbm.member_id
All the fields that list multiple entries in the result are messing up the rowcount in your resultset.
To Fix that you can do:
SELECT pbm.member_id
u.name,
u.surname,
u.country,
pt.tasks_completed
FROM (SELECT
p.project_id, p.member_id
FROM project_board_members p
WHERE p.project_id = '5'
LIMIT 1
) AS pbm
JOIN users u
ON (u.id = pbm.member_id)
JOIN project_team pt
ON (pt.user_id = pbm.member_id)