I am using sqllite to create two tables
CREATE TABLE NAMES(Id integer PRIMARY KEY, Name text);
CREATE TABLE PHONE(Id inetegr PRIMARY KEY, PersonID integer, Number integer,
FOREIGN KEY (PersonID) REFERENCES NAMES(Id)
);
Then, I have written a qry to slect all people having more than 2 phones
select count(PersonID) as counts,Name
from PHONE
INNER JOIN NAMES on NAMES.Id=PHONE.PersonID
group by PersonID
having counts>=2;
The output is like below
2|Tom
However, I dont want to print the count and just need the names, how to change my query to just print the name..
you can try like below
select Name from PHONE
INNER JOIN NAMES on NAMES.Id=PHONE.PersonID
group by Name
having count(distinct Number)>=2;
You can try below
select Name from PHONE
INNER JOIN NAMES on NAMES.Id=PHONE.PersonID
group by Name having count(PersonID)>=2;
Related
I need to select the item name and the vendor name for each item that belongs to the vendor with a rating bigger than 4. And I can't find a way, I know it's something with joins but the 2 of them have the same column name.
CREATE TABLE venedors(
id int PRIMARY KEY,
name varchar2(20),
rating int)
CREATE TABLE items(
id int PRIMARY KEY,
name varchar2(20),
venedorId int references venedors(id))
If i understanded your problem.
Select items.name as itemName, venedors.name as vendorName
from items
inner join venedors
on items.venedorId = venedors.id
where venedors.rating > 4
If you want get all the vendors irrespective whether there are items associated with vendors or not, then try with left join as shown below:
Select v.name as vendorName, i.name as itemName
from venedors v
left join items i
on i.venedorId = v.id
where v.rating > 4
I have the following tables:
CREATE TABLE Subject
(
Subject_Code INTEGER,
Subject_Year VARCHAR (8),
PRIMARY KEY (Subject_Code, Subject_Year),
Teacher_ID INTEGER REFERENCES
);
CREATE TABLE Teacher
(
TeacherID INTEGER PRIMARY KEY,
FirstName TEXT,
Department_ID INTEGER References Academic Department(Department_ID)
);
CREATE TABLE Subject-taken
(
Marks_Obtained INTEGER,
Subject_Code INTEGER REFERENCES subject (Subject_Code),
Candidate_ID INTEGER REFERENCES Candidate (Candidate_ID),
PRIMARY KEY (Subject_Code, Candidate_ID)
);
CREATE TABLE Academic_Department
(
Department_ID INTEGER PRIMARY KEY,
Department_Name TEXT
);
I've already tried the following select statement
SELECT m.subject_code,
MIN (marks_obtained) AS Min_Marks,
MAX (marks_obtained) AS Max_Marks
FROM Subject-taken m, Subject a
GROUP BY m.Subject_Code;
Want to use the join function any suggestions on where to use it in order to join the departments with subjects and students
Make use of joins to link your data between tables. Use group by to make statistics by some fields. You can try something like this:
SELECT
Subjects.Subject_Code,
Subjects.Subject_Name,
Teachers.TeacherID,
Academic_Department.Department_ID,
min(Subject-taken.Marks_Obtained) as min_marks,
max(Subject-taken.Marks_Obtained) as max_marks,
avg(Subject-taken.Marks_Obtained) as avg_marks,
stddev_samp(subject-taken.Marks_Obtained) as stddev_marks
FROM
Subjects LEFT JOIN
Teachers ON Subjects.TeacherID = Subjects.TeacherID LEFT JOIN
Academic_Department ON Teachers.Department_ID = Academic_Department.Department_ID LEFT JOIN
Subject-taken ON Subjects.Subject_Code = Subject-taken.Subject_Code
GROUP BY
Subjects.Subject_Code,
Subject.Subject_Name,
Teacher.TeacherID,
Academic_Department.Department_ID
I don't really know if stddev_samp is the aggregate function you need, stddev_pop is also available. Please refer to this PostgreSQL documentation table to find out.
I have two tables created with SQL code:
CREATE TABLE
TicketSales(
purchase# Number(10),
client# Integer CONSTRAINT fk1 REFERENCES Customers,
PRIMARY KEY(purchase#));
CREATE TABLE Customers(
client# Integer,
name Char(30),
Primary Key(client#);
Basically table TicketSales holds ticket sales data and client# is foreign key referenced in customers table. I would like to count names that are in TicketSales table. i tried below code with no success:
select Count(name)
From Customers
Where Customers.Client#=TicketSales.Client#
Group by Name;
Any help appreciated.
Thanks,
If you want a count by each name, then include name in the select and group by clauses
select c.Name, Count(*)
From Customers c
INNER JOIN TicketSales t ON c.Client# =t.Client#
Group by c.Name;
If you want just the count of names, not tickets, then use
select Count(*)
From Customers c
;
Or, for a count of individuals who have tickets recrded against them:
select Count(DISTINCT t.Client#)
From TicketSales t
;
I am working on a project where I have a table of
all_names(
team_name TEXT,
member_name TEXT,
member_start INT,
member_end INT);
What I have been tasked with is creating a table of
participants(
ID SERIAL PRIMARY KEY,
type TEXT,
name TEXT);
which contains all team and member names as their own entries. Type may be either "team" or "member".
To compliment this table of participants I am trying to create a cross-reference table that allows a member to be referenced to a team by ID and vice versa. My table looks like this:
belongs_to(
member_id INT REFERENCES participants(ID),
group_id INT REFERENCES participants(ID),
begin_year INT,
end_year INT,
PRIMARY KEY (member_id, group_id);
I am unsure of how to proceed and populate the table properly.
The select query I have so far is:
SELECT DISTINCT ON (member_name, team_name)
id, member_name, team_name, member_begin_year, member_end_year
FROM all_names
INNER JOIN artists ON all_names.member_name = participants.name;
but I am unsure of how to proceed. What is the proper way to populate the cross reference table?
Probably the easiest solution is to use a few statements. Wrap this is a transaction to make sure you don't get concurrency issues:
BEGIN;
INSERT INTO participants (type, name)
SELECT DISTINCT 'team', team_name
FROM all_names
UNION
SELECT DISTINCT 'member', member_name
FROM all_names;
INSERT INTO belongs_to
SELECT m.id, g.id, a.member_start, a.member_end
FROM all_names a
JOIN participants m ON m.name = a.member_name
JOIN participants g ON g.name = a.team_name;
COMMIT;
Members that are part of multiple teams get all of their memberships recorded.
I have three tables:
group:
id - primary key
name - varchar
profile:
id - primary key
name - varchar
surname - varchar
[...etc...]
profile_group:
profile_id - integer, foreign key to table profile
group_id - integer, foreign key to table group
Profiles may be in many groups. I have group named "Users" with id=1 and I want to assign all users to this group but only if there was no such entry for the table profiles.
How to do it?
If I understood you correctly, you want to add entries like (profile_id, 1) into profile_group table for all profiles, that were not in this table before. If so, try this:
INSERT INTO profile_group(profile_id, group_id)
SELECT id, 1 FROM profile p
LEFT JOIN profile_group pg on (p.id=pg.profile_id)
WHERE pg.group_id IS NULL;
What you want to do is use a left join to the profile group table and then exclude any matching records (this is done in the where clause of the below SQL statement).
This is faster than using not in (select xxx) since the query profiler seems to handle it better (in my experience)
insert into profile_group (profile_id, group_id)
select p.id, 1
from profiles p
left join profile_group pg on p.id = pg.profile_id
and pg.group_id = 1
where pg.profile_id is null