From this Question we learned to use a subquery to find information once-removed.
Subquery we learned :
SELECT * FROM papers WHERE writer_id IN ( SELECT id FROM writers WHERE boss_id = 4 );
Now, I need to search a table, both in column values that table, and in column values related by id on another table.
Here are the same tables, but col values contain more text for our "searching" reference...
writers :
id
name
boss_id
1
John Jonno
2
2
Bill Bosworth
2
3
Andy Seaside
4
4
Hank Little
4
5
Alex Crisp
4
The writers have papers they write...
papers :
id
title
writer_id
1
Boston
1
2
Chicago
4
3
Cisco
3
4
Seattle
2
5
North
5
I can use this to search only the names on writers...
Search only writers.name : (Not what I want to do)
SELECT * FROM writers WHERE LOWER(name) LIKE LOWER('%is%');
Output for above search : (Not what I want to do)
id
name
boss_id
5
Alex Crisp
4
I want to return cols from writers (not papers), but searching text both in writers.name and the writers.id-associated papers.title.
For example, if I searched "is", I would get both:
Alex Crisp (for 'is' in the name 'Crisp')
Andy Seaside (because Andy wrote a paper with 'is' in the title 'Cisco')
Output for "is" search :
id
title
writer_id
2
Chicago
4
4
Seattle
2
Here's what I have that doesn't work:
SELECT * FROM papers WHERE LOWER(title) LIKE LOWER('%is%') OR writer_id ( writers=writer_id WHERE LOWER(name) LIKE LOWER('%$is%') );
The best way to express this criteria is by using a correlated query with exists:
select *
from writers w
where Lower(w.name) like '%is%'
or exists (
select * from papers p
where p.writer_id = w.id and Lower(p.title) like '%is%'
);
Note you don't need to use lower on the string you are providing, and you should only use lower if your collation truly is case-sensitive as using the function makes the search predicate unsargable.
Since you want to return cols from writers (not papers) you should select them first, and use stuff from papers in the criteria
select *
from writers w
where
w.name like '%is%'
or
w.id in (select p.writer_id
paper p
where p.title like '%is%'
)
You can add your LOWER functions (my sql environment is not case-sensitive, so I didn't need them)
I have two tables Infos and nationalities like this :
1) Table infos:
id(pk)
name
nationality(varchar) accept multiple nationalities
1
John
1,2,3
2
Camilia
2,4
1) Table nationalities :
id(pk) int
desig
1
German
2
Turkey
3
Algeria
4
Qatar
I want to get in the output something like this:
desig
count
German
1
Turkey
2
Algeria
1
Qatar
1
So for that I tried something like this(but it did not help):
$total_nationalite = DB::table('infos')
->select('desig', 'nationalities.id',DB::raw('COUNT(*) as count'))
->join('nationalities', DB::raw('CAST(nationalities.id as varchar)'), '=', 'infos.nationality')
->groupBy('desig','nationalities.id')
->get();
please any suggestion with the query builder or with a simple query in postgres.
Having a comma separated list of values text in nationality field is a bad idea. Have an array of integers or - much better - a normalized design. Anyway here is a native query solution.
select desig, count(*) count
from
(
select unnest(string_to_array(nationality, ','))::integer nat_id
from infos
) t
join nationalities n on t.nat_id = n.id
group by desig;
DB Fiddle
desig
count
German
1
Qatar
1
Algeria
1
Turkey
2
I am using SQL Server
I have a table
id--dish--restaurant
1 pasta Italian
2 noodles Chinese
3 beef Chinese
4 noodles Chinese
How can I use COUNT() to get the following result, to count each dish for every UNIQUE restaurant
Restaurant Dish Count
Italian 1
Chinese 3
Any suggestions would be helpful.
That's a simple aggregation query:
select restaurant, count(*) dish_count
from mytbale
group by restaurant
Use group by:
Select restaurant, count(*)
From table
Group by restaurant
Replacing table with your table's name
I am investigating the benefits of Oracle Text search, and currently am looking at collecting search text data from multiple (related) tables and storing the data in the smaller table in a 1-to-many relationship.
Consider these 2 simple tables, house and inhabitants, and there are NEVER any uninhabited houses:
HOUSE
ID Address Search_Text
1 44 Some Road
2 31 Letsby Avenue
3 18 Moon Crescent
INHABITANT
ID House Name Nickname
1 1 Jane Doe Janey
2 1 John Doe JD
3 2 Jo Smythe Smithy
4 2 Percy Plum PC
5 3 Apollo Lander Moony
I want to to write SQL that updates the HOUSE.Search_Text column with text from INHABITANT. Now because this is a 1-to-many, the SQL needs to collate the data in INHABITANT for each matching row in house, and then combine the data (comma separated) and update the Search_Text field.
Once done, the Oracle Text search index on HOUSE.Search_Text will return me HOUSEs that match the search criteria, and I can look up INHABITANTs accordingly.
Of course, this is a very simplified example, I want to pick up data from many columns and Full Text Search across fields in both tables.
With the help of a colleague we've got:
select id, ADDRESS||'; '||Names||'; '||Nicknames as Search_Text
from house left join(
SELECT distinct house_id,
LISTAGG(NAME, ', ') WITHIN GROUP (ORDER BY NAME) OVER (PARTITION BY house_id) as Names,
LISTAGG(NICKNAME, ', ') WITHIN GROUP (ORDER BY NICKNAME) OVER (PARTITION BY house_id) as Nicknames
FROM INHABITANT)
i on house.id = i.house_id;
which returns:
1 44 Some Road; Jane Doe, John Doe; JD, Janey
2 31 Letsby Avenue; Jo Smythe, Percy Plum; PC, Smithy
3 18 Moon Crescent; Apollo Lander; Moony
Some questions:
Is this an efficient query to return this data? I'm slightly
concerned about the distinct.
Is this the right way to use Oracle Text search across multiple text fields?
How to update House.Search_Text with the results above? I think I need a correlated subquery, but can't quite work it out.
Would it be more efficient to create a new table containing House_ID and Search_Text only, rather than update House?
My problem is Play! Framework / JPA specific. But I think it's applicable to general SQL syntax.
Here is a sample query with a simple JOIN:
return Post.find(
"select distinct p from Post p join p.tags as t where t.name = ?", tag
).fetch();
It's simple and works well.
My question is: What if I want to JOIN on more values in the same table?
Example (Doesn't work. It's a pseudo-syntax I created):
return Post.find(
"select distinct p from Post p join p.tags1 as t, p.tags2 as u, p.tags3 as v where t.name = ?, u.name = ?, v.name = ?", tag1, tag2, tag3,
).fetch();
Your programming logic seems okay, but the SQL statement needs some work. Seems you're new to SQL, and as you pointed out, you don't seem to understand what a JOIN is.
You're trying to select data from 4 tables named POST, TAG1, TAG2, and TAG3.
I don't know what's in these tables, and it's hard to give sample SQL statements without that information. So, I'm going to make something up, just for the purposes of discussion. Let's say that table POST has 6 columns, and there's 8 rows of data in it.
P Fname Lname Country Color Headgear
- ----- ----- ------- ----- --------
1 Alex Andrews 1 1 0
2 Bob Barker 2 3 0
3 Chuck Conners 1 5 0
4 Don Duck 3 6 1
5 Ed Edwards 2 4 2
6 Frank Farkle 4 2 1
7 Geoff Good 1 1 0
8 Hank Howard 1 3 0
We'll say that TAG1, TAG2, and TAG3 are lookup tables, with only 2 columns each. Table TAG1 has 4 country codes:
C Name
- -------
1 USA
2 France
3 Germany
4 Spain
Table TAG2 has 6 Color codes:
C Name
- ------
1 Red
2 Orange
3 Yellow
4 Green
5 Blue
6 Violet
Table TAG3 has 4 Headgear codes:
C Name
- -------
0 None
1 Glasses
2 Hat
3 Monacle
Now, when you select data from these 4 tables, for P=6, you're trying to get something like this:
Fname Lname Country Color Headgear
----- ------ ------- ------ -------
Frank Farkle Spain Orange None
First thing, let's look at your WHERE clause:
where t.name = ?, u.name = ?, v.name = ?
Sorry, but using commas like this is a syntax error. Normally you only want to find data where all 3 conditions are true; you do this by using AND:
where t.name=? AND u.name=? AND v.name=?
Second, why are you joining tables together? Because you need more information. Table POST says that Frank's COUNTRY value is 4; table TAG1 says that 4 means Spain. So we need to "join" these tables together.
The ancient (before 1980, I think) way to join tables is to list more than one table name in the FROM clause, separated by commas. This gives us:
SELECT P.FNAME, P.LNAME, T.NAME As Country, U.NAME As Color, V.NAME As Headgear
FROM POST P, TAG1 T, TAG2 U, TAG3 V
The trouble with this query is that you're not telling it WHICH rows you want, or how they relate to each other. So the database generates something called a "Cartesian Product". It's extremely rare that you want a Cartesian Product - normally this is a HUGE MISTAKE. Even though your database only has 22 rows in it, this SELECT statement is going to return 768 rows of data:
Alex Andrews USA Red None
Alex Andrews USA Red Glasses
Alex Andrews USA Red Hat
Alex Andrews USA Red Monacle
Alex Andrews USA Orange None
Alex Andrews USA Orange Glasses
...
Hank Howard Spain Violet Monacle
That's right, it returns every possible combination of data from the 4 tables. Imagine for a second that the POST table eventually grows to 20000 rows, and the three TAG tables have 100 rows each. The whole database would be less than a megabyte, but the Cartesian Product would have 20,000,000,000 rows of data -- probably about 120 GB of data. Any database engine would choke on that.
So if you want to use the Ancient way of specifying tables, it is VERY IMPORTANT to make sure that your WHERE clause shows the relationship between every table you're querying. This makes a lot more sense:
SELECT P.FNAME, P.LNAME, T.NAME As Country, U.NAME As Color, V.NAME As Headgear
FROM POST P, TAG1 T, TAG2 U, TAG3 V
WHERE P.Country=T.C AND P.Color=U.C AND P.Headgear=V.C
This only returns 8 rows of data.
Using the Ancient way, it's easy to accidentally create Cartesian Products, which are almost always bad. So they revised SQL to make it harder to do. That's the JOIN keyword. Now, when you specify additional tables you can specify how they relate at the same time. The New Way is:
SELECT P.FNAME, P.LNAME, T.NAME As Country, U.NAME As Color, V.NAME As Headgear
FROM POST P
INNER JOIN TAG1 T ON P.Country=T.C
INNER JOIN TAG2 U ON P.Color=U.C
INNER JOIN TAG3 V ON P.Headgear=V.C
You can still use a WHERE clause, too.
SELECT P.FNAME, P.LNAME, T.NAME As Country, U.NAME As Color, V.NAME As Headgear
FROM POST P
INNER JOIN TAG1 T ON P.Country=T.C
INNER JOIN TAG2 U ON P.Color=U.C
INNER JOIN TAG3 V ON P.Headgear=V.C
WHERE P.P=?
If you call this and pass in the value 6, you get only one row back:
Fname Lname Country Color Headgear
----- ------ ------- ------ --------
Frank Farkle Spain Orange None
As was mentioned in the comments, you are looking for an ON clause.
SELECT * FROM TEST1
INNER JOIN TEST2 ON TEST1.A = TEST2.A AND TEST1.B = TEST2.B ...
See example usage of join here:
http://en.wikibooks.org/wiki/Java_Persistence/Relationships#Join_Fetching