I essentially have 4 tables, but not all the tables have common fields
Table 1 has A
Table 2 has A and B
Table 3 has B and C
Table 4 has C
so when I tried to join them all, it doesn't work because
SQLITE_ERROR: cannot join using column C - column not present in
all tables
Which I understand, not all the table share the same columns.
I tried creating a view (TABLE_ABC) using "table1, table2, and table3", then tried doing a join to that view
Join TABLE_ABC using (C)
but I get the same SQLITE Error.
So my questions are:
Is there a way to join all 4 tables even though they all do not share a column? Do I just need to create a 5th table using "table1, table2, and table3" and connect 4 to that?
Can you do a join to a view?
Related
I have this query
select * from task
inner JOIN ec_child AS child ON child.id = task.for
inner join ec_family_member as mother ON task.for = mother.id
WHERE task.group_id = 'NEWBORNCHW'
AND task.status = 'READY'
AND task.code IN ('mother_followup', 'new_born_follow_up')
whenever I remove one of inner join I get data for mother_followup and new_born_follow_up from task table but if both inner join is present in query then I get data for new_born_follow_up from task table only, why is that why data I don't get data for mother_followup and new_born_follow_up from task table.
Thanks in advance!
fiddle:
https://www.db-fiddle.com/f/qTEs3492Lgoo3VunB7bWem/0
Edit:
concept is
table_for_mother_and_child_ids.
id_for_mother_or_child
1
2
mother.
id | name
1 | XYZ
child.
id | name
2 | details
Desired Output:
id |mother.name|child.name
my question is can we do inner join on tables that are not related, like is it necessary that first inner join with table has to have a relation with 3rd table on which 2nd inner join is made, or inner joins/joins can be on independent tables?
Maybe I'm missing something here but I feel this isn't such an uncommon thing to do in SQL.
I have a DB table1 with a lot of values, and several other tables that each have a foreign key to the primary key of table1. I want for every row in table1 to generate a list of all the tables which reference it.
For example, I have a table called Books, which contains rows describing different books. I then have a table called SchoolLibrary which contains rows of all the books their library has and where they are stored. Not all the books in Books appear in school library. I then have a table called PublicLibrary, which similarly contains rows of all the books they have, as well as information about who checked them out.
I would then want to select all the values in Books and add a column with a list of which libraries reference that book, so it would say either {1, []} or {1, [PublicLibrary]} or {1, [SchoolLibary, PublicLibrary]} for book with id 1, etc...
Perhaps more useful would be not only which table references it, but also the id of the row in that table which references it. So the list would be something like {1, [PublicLibrary: 5]}, so the row with id 5 in PublicLibrary references the book with id 1.
How can I do this?
After discussing with someone I realized there's a simple solution to this question. Just do a LEFT JOIN of all the tables
SELECT Books._id, SchoolLibrary._id, PublicLibrary._id
FROM Books
LEFT JOIN SchoolLibrary ON Books._id = SchoolLibrary.bookId
LEFT JOIN PublicLibrary ON Books._id = PublicLibrary.bookId
This will return a table with all the values in Books, with a column for the other tables. If the other tables reference Books, the id of which entry references Books will be stored. If it doesn't, it'll be NULL
For example (where SchoolLibrary and PublicLibrary have _id, bookId as columns):
Books SchoolLibrary PublicLibrary
----- ------------- -------------
1 1 | 1 1 | 2
2 2 | 3 2 | 3
3
With the above script, it will return the following:
Book._id SchoolLibrary._id PublicLibrary._id
-------- ----------------- -----------------
1 1
2 1
3 2 2
I have an SQLite Database, two of the tables look like this:
ID Name
1 Test1
2 Test2
3 Test3
4 Test4
ID Color
1 Blue
1 White
1 Red
2 Green
2 Red
4 Black
In the first Tables, ID is unique, the second table lists colors an ID has, it can be from 0 to n colors.
Now I want to select all Names exactly once, that have one or more given color. Lets say, I want to have all names associated with blue, white and/or green. The resultset should have the IDs 1 and 2.
I am completly lost here, as I normally dont do any SQL. I am just familiar with very basic SQL. What I would do is Join the tables together, but I dont know how I do that, as ID is not unique in the second table. Also there would be the problem of IDs beeing duplicated in the resultset, if it has multiple colors that I want to select.
Thanks in advance for any help.
You don't need a join for this. Get the list of IDs from the color table in a subquery, and fetch the names from the test table with an in clause:
sqlite> select * from tests where id in
(select id from colors where name in ('Blue', 'White', 'Green'));
1|Test1
2|Test2
Duplicates don't matter in the subquery, but you could use distinct if you want that list without duplicates in other contexts.
I have a data structure where I have two tables Alpha and Beta and they are one to many. For the sake of an example let's say that table alpha has a column for "State" and table B has "Colors you like" and you can pick more than one. I would like to build a report that has columns like this:
STATE TOTAL RED GREEN BLUE
Alaska 5 1 3 1
Florida 2 2 2 0
New York 10 5 8 1
The column TOTAL would be a count of the records in Alpha and as you can see due to the one to many relationship the sum of the colors can exceed the count. I suppose it could be less as well if people didn't like colors.
How would you build a report like this. I'll be using SQL Server and Reporting Services in .NET so it could either be a complex query that I just dump into a data table report or a less complex query with some counting and totaling done by the report. I just don't really know the best way to tackle this.
Since you don't know which colors are going to be the columns you should use the Matrix Control
You'll need to set up the query
SELECT
a.State,
b.ColorName,
COUNT(b.ColorID) ColorCount
FROM
alpha a
LEFT JOIN beta b
ON a.id = b.a_id
GROUP BY
a.State,
b.ColorName
Just drag state for the rows, color for the columns and ColorCount for the data (Count(ColorID) will display in the data field))
Note: The LEFT JOIN and Count(ColorID) instead of Count(*) are required if you want a 0 value to appear correctly.
If you did know the colors you could use PIVOT or the sum case technique
SELECT state SUM(CASE WHEN Color = 'RED' THEN 1 ELSE 0 END) as Red, ...
I came across a problem in AX 2009 and I have to admit I'm basically clueless.
I would like to build a view (based on an AOT query or not; but from what I understand you can do more using an AOT query than strictly with a view) using a table which looks like this:
id status date
1 IN 10/10/2011
1 OUT 11/10/2011
2 OUT 12/10/2011
3 IN 13/10/2011
4 IN 14/10/2011
4 OUT 15/10/2011
The view would ideally look like this:
id IN_Date OUT_Date
1 10/10/2011 11/10/2011
2 *NULL* 12/10/2011
3 13/10/2011 *NULL*
4 14/10/2011 15/10/2011
In strict SQL or even using Microsoft Access it's a trivial task to do but I can't find a way to do it in AX 2009 since there is no "AS" option in views' fields. I don't want to use display methods since I want the view to be accessed from outside of AX. Any hint would be greatly appreciated!
You would like to do a full outer join on the table (joined with itself).
This is not supported in X++ or as a query joinMode, but can be simulated using two intermediate views with outer join combined with a union.
View 1:
select id, date as dateIn from table as table1
outer join date as dateOut from table as table2
where table2.id == table1.id and
table1.status == Status::In and
table2.status == Status::Out
View 2:
select id, date as dateOut from table as table1
outer join date as dateIn from table as table2
where table2.id == table1.id and
table1.status == Status::Out and
table2.status == Status::In
View 3:
select id, dateIn, dateOut from view1
union
select id, dateIn, dateOut from view2
The above is more or less SQL, which can be turned into AX queries and views.
A way to do that is given in this answer.