I am joining three tables and generating a new table. However, the new table is empty. Below is my query:
CREATE TABLE TEMP (WORD, TOTALCOUNT, AGENCYNAME) AS
SELECT NSFABSTRACTS.WORD, DOCUMENT_FREQUENCY.TOTALCOUNT, AGENCY.AGENCYNAME
FROM NSFABSTRACTS LEFT JOIN DOCUMENT_FREQUENCY
ON NSFABSTRACTS.WORD=DOCUMENT_FREQUENCY.WORD
INNER JOIN AGENCY
ON NSFABSTRACTS.FILEID=AGENCY.FILEID;
When I do not add the top line to create a table, the results look fine. But when I add the top line, it generates an empty table. Any thoughts why is this?
I think it is because of your inner join; I cannot say surely without looking at your data in the database. but try following;
CREATE TABLE TEMP (WORD, TOTALCOUNT, AGENCYNAME) AS
SELECT NSFABSTRACTS.WORD, DOCUMENT_FREQUENCY.TOTALCOUNT, AGENCY.AGENCYNAME
FROM NSFABSTRACTS LEFT JOIN DOCUMENT_FREQUENCY
ON NSFABSTRACTS.WORD=DOCUMENT_FREQUENCY.WORD
LEFT JOIN AGENCY
ON NSFABSTRACTS.FILEID=AGENCY.FILEID;
Related
I want to do a join with another table. I followed the tutorial on the site and the my code compiles but it's not performing the join and instead just selects the first table.
SELECT
"table1.col1"
"table1.col2"
"table1.col3"
FROM
"table1"
JOIN "table2" ON "table1"."col1" = "table2"."col1"
LIMIT
1
It is only returning the data from table1 and not concatenating the columns where the condition for table1 and table2 is met.
I execute the query using the following code:
Entity::find()
.from_raw_sql(Statement::from_string(DatabaseBackend::Postgres, query.to_owned()))
.all(&self.connection)
.await?
That returns a Vec<Model>. Is this the correct way? Also, how can I build a SQL statement using an Entity as the base which looks like SELECT * from "table1".
After 'SELECT' (and before 'FROM') you are specifying which columns
to include in the output,
and you are selecting only three columns from table1 in your code.
Add the columns you want to include from table2 here, and you may get
the results you want.
Is it possible to add a new column to an existing table from another table using insert or update in conjunction with full outer join .
In my main table i am missing some records in one column in the other table i have all those records i want to take the full record set into the maintable table. Something like this;
UPDATE maintable
SET all_records= othertable.records
FROM
FULL JOIN othertable on maintable.col = othertable.records;
Where maintable.col has same id a othertable.records.
I know i could simply join the tables but i have a lot of comments in the maintable i don't want to have to copy paste back in if possible. As i understand using where is equivalent of a left join so won't show me what i'm missing
EDIT:
What i want is effectively a new maintable.col with all the records i can then pare down based on presence of records in other cols from other tables
Try this:
UPDATE maintable
SET all_records = o.records
FROM othertable o
WHERE maintable.col = o.records;
This is the general syntax to use in postgres when updating via a join.
HTH
EDIT
BTW you will need to change this - I used your example, but you are updating the maintable with the column used for the join! Your set needs to be something like SET missingcol = o.extracol
AMENDED GENERALISED ANSWER (following off-line chat)
To take a simplified example, suppose that you have two tables maintable and subtable, each with the same columns, but where the subtable has extra records. For both tables id is the primary key. To fill maintable with the missing records, for pre 9.5 versions of Postgres you must use the following syntax:
INSERT INTO maintable (SELECT * FROM subtable s WHERE NOT EXISTS
(SELECT 1 FROM maintable m WHERE m.id = s.id));
Since 9.5 there is a (preferred) alternative:
INSERT INTO maintable (SELECT * FROM subtable) ON CONFLICT DO NOTHING;
This is preferred because (apart from being simpler) it avoids the situation that has been known to arise in the former, where a race condition is created between the INSERT and the sub-SELECT.
Obviously when the columns are different, you need to specify in the INSERT statement which columns are inserted from which. Something like:
INSERT INTO maintable (id, ColA, ColB)
(SELECT id, ColE, ColG FROM subtable ....)
Similarly the common field might not be id in both tables. However, the simplified example should be enough to point you in the right direction.
I'm joining different tables with countries information, where one of them (cty) is the main table with the countries' names. All the tables have a column c, linking to the primary key in cty (also called c).
To join them all, I first used
select * from cty
full join table1 using (c)
full join table2 using (c)
This gives me all the countries in cty, but I want only the countries present in the other tables. To solve this, I tried
select * from table1
full join table2 using (c)
join cty using (c)
This solves the problem about the number of lines, but now the main columns are the last in the table.
Is there a way to keep the columns from cty in the beginning (left side) of the table without specifying all the column names of all tables (I have many tables), and keep only the lines present in the secondary tables?
select * from cty
right join
(select * from table1
full join table2 using(id)
) fj on fj.id = tt1.id
;
Check it: http://rextester.com/HCA83570
I have a view and two tables. Tables one and two have the same columns, but table one is has as small number of records, and table two has old data and a huge number of records.
I have to join a view with these two tables to get the latest data from table one; if a record from the view is not available in table one then I have to select the record from table two.
How can i achieve this with MySQL?
I came to know by doing some research in internet that we can't apply full join and sub query in from clause.
Just do a simple UNION of the results excluding the records in table2 that are already mentioned in table1:
SELECT * FROM table1
UNION
SELECT * FROM table2
WHERE NOT EXISTS (SELECT * FROM table1 WHERE table2.id = table1.id)
Something like this.
SELECT *
FROM view1 V
INNER JOIN (SELECT COALESCE(a.commoncol, b.commoncol) AS commoncol
FROM table1 A
FULL OUTER JOIN table2 B
ON A.commoncol = B.commoncol) C
ON v.viewcol = c.commoncol
If you are using Mysql then check here to simulate Full Outer Join in MySQL
are you trying to update the view from two tables where old record in view needs to be overwritten by latest/updated record from table1 and non existant records from table1 to be appended from table2?
, or are you creating a view from two tables?
Let us consider two tables
table1 - name,id,publisher_name,exp_date
table2-book_id,price,discount,last_date
I have to retrieve the name, id,publisher_name from table1 and price, last_date from table2
I wrote a code in active record rails 2
Table1.find(:all,:select=>"table1.name,table1.publisher_name,table1.id,table2.last_date,table2.price",:joins=>"LEFT OUTER JOIN table1s on table1s.id= table2s.book_id")
in this code by selecting multiple column name we need write that table name repeatedly,
need a simple code to avoid this problem
if the selected columns are not present in both tables you don't need to write the tablename as a prefix. You also don't need to name the table2 in front of "book_id". You only need them if the column-names are ambigious.
Table1.find( :all, :select=> "name, publisher_name, id, last_date, price", :joins => "LEFT OUTER JOIN table1s on table1s.id = book_id")