Hello I've been stuck with one SQL query for my assignment and was hoping for some help.
I need to get the Project ID for the best executed project -the project where (VERY_GOOD record count + GOOD record count) - (VERY_BAD record count + BAD record count) is greatest
My schema and test records in database (HSQLDB)
CREATE TABLE
PROJECT
(
ID IDENTITY NOT NULL PRIMARY KEY,
PROJECT_NAME VARCHAR(255) NOT NULL
);
CREATE TABLE
RECORD
(
ID IDENTITY NOT NULL PRIMARY KEY,
RESULT VARCHAR(255) NOT NULL,
);
CREATE TABLE
RECORD_PROJECT
(
PROJECT_ID INTEGER NOT NULL,
RECORD_ID INTEGER NOT NULL,
PRIMARY KEY(PROJECT_ID, RECORD_ID),
FOREIGN KEY (PROJECT_ID) REFERENCES PROJECT(ID) ON DELETE CASCADE,
FOREIGN KEY (RECORD_ID) REFERENCES RECORD(ID)
);
And test data:
INSERT INTO PROJECT (PROJECT_NAME) VALUES ('Bake a cake');
INSERT INTO PROJECT (PROJECT_NAME) VALUES ('Clean the house');
INSERT INTO RECORD (RESULT) VALUES ('GOOD');
INSERT INTO RECORD (RESULT) VALUES ('VERY_GOOD');
INSERT INTO RECORD (RESULT) VALUES ('VERY_GOOD');
INSERT INTO RECORD (RESULT) VALUES ('BAD');
INSERT INTO RECORD (RESULT) VALUES ('VERY_BAD');
INSERT INTO RECORD_PROJECT (PROJECT_ID, RECORD_ID) VALUES (0,0);
INSERT INTO RECORD_PROJECT (PROJECT_ID, RECORD_ID) VALUES (1,1);
INSERT INTO RECORD_PROJECT (PROJECT_ID, RECORD_ID) VALUES (1,2);
INSERT INTO RECORD_PROJECT (PROJECT_ID, RECORD_ID) VALUES (0,3);
INSERT INTO RECORD_PROJECT (PROJECT_ID, RECORD_ID) VALUES (1,4);
(I removed unrelated fields from tables)
So with this data I have 3 good records and 2 bad, I would need to get the project which has the highest 'rating', which according to this right now would be Clean the house with 3 good ratings over 2 negative for other project.
Maybe someone would figure this out, thanks!
That should be the (not testet) SQL in MySQL-Dialect:
SELECT rp.PROJECT_ID, p.PROJECT_NAME
SUM(CASE WHEN rp.RECORD_ID < 3 THEN 1 ELSE 0 END) AS rating
FROM RECORD_PROJEKT AS rp
JOIN PROJECT AS p ON p.ID = rp.PROJECT_ID
GROUP BY rp.PROJECT_ID
ORDER BY rating DESC
Related
Let's say I have two tables called widgetCustomer and widgetSale. On an insert in widgetSale I want to add a timestamp to the widgetSale row and add the sale id as last_order_id to the widgetCustomer table.
I understand using AFTER INSERT ON will result in an error on trying to update the NEW row, hence we need to use BEFORE INSERT ON clause. Which brings forward a new issue that AUTO_INCREMENT has not yet generated a id for sale hence last_order_id would all be zero. There is a method to do this at MySQL/MariaDB TRIGGER but it seems to fail on my system (i.e., the last order ids are still zero).
As a work around I'm using two different triggers one before insert and one after insert. Although it does work I'm keen to learn if there is a possible flaws with the method above and is there a better way of doing this (both in terms of performance and data integrity).
My code is given below:
DROP TABLE IF EXISTS widgetSale;
DROP TABLE IF EXISTS widgetCustomer;
DROP TABLE IF EXISTS widgetLog;
CREATE TABLE widgetCustomer ( id integer primary key AUTO_INCREMENT, name TEXT, last_order_id INT, stamp TEXT );
CREATE TABLE widgetSale ( id integer primary key AUTO_INCREMENT, item_id INT, customer_id INTEGER, quan INT, price INT, stamp TEXT );
CREATE TABLE widgetLog ( id integer primary key AUTO_INCREMENT, stamp TEXT, event TEXT, username TEXT, tablename TEXT, table_id INT);
INSERT INTO widgetCustomer (name) VALUES ('Bob');
INSERT INTO widgetCustomer (name) VALUES ('Sally');
INSERT INTO widgetCustomer (name) VALUES ('Fred');
SELECT * FROM widgetCustomer;
CREATE TRIGGER stampSale BEFORE INSERT ON widgetSale
FOR EACH ROW BEGIN
SET NEW.stamp = CURRENT_TIMESTAMP();
END
CREATE TRIGGER stampOnRest AFTER INSERT ON widgetSale
FOR EACH ROW BEGIN
UPDATE widgetCustomer SET last_order_id = NEW.id, stamp = CURRENT_TIMESTAMP()
WHERE widgetCustomer.id = NEW.customer_id;
INSERT INTO widgetLog (stamp, event, username, tablename, table_id)
VALUES (CURRENT_TIMESTAMP(), 'INSERT', 'TRIGGER', 'widgetSale', NEW.id);
END
INSERT INTO widgetSale (item_id, customer_id, quan, price) VALUES (1, 3, 5, 1995);
INSERT INTO widgetSale (item_id, customer_id, quan, price) VALUES (2, 2, 3, 1495);
INSERT INTO widgetSale (item_id, customer_id, quan, price) VALUES (3, 1, 1, 2995);
SELECT * FROM widgetSale;
SELECT * FROM widgetCustomer;
SELECT * FROM widgetLog;
I'm using mariadb 10.6.* on Archlinux.
I'm trying to create a sql table in data base in VS that has room and userid column, but the sql will only accept your input if the userid exists in users table and room exists in rooms tables
Allows:
Users table:
Userid
1
2
3
RoomUsers table:
Room ----- User
1 1
2. 1
1. 2
1. 3
2. 3
Won't allow:
Users table:
Userid
1
2
RoomUsers table:
Room ----- User
1 4
Normal foreign key wont work because it only allows one of each index and not multiple, how can I allow what I need to occur,to happen?
(This would be a mess in comments)
Probably we are having an XY problem here. The thing you describe is simply solved with a foreign key. ie:
CREATE TABLE users (id INT IDENTITY NOT NULL PRIMARY KEY, ad VARCHAR(100));
CREATE TABLE rooms (id INT IDENTITY NOT NULL PRIMARY KEY, ad VARCHAR(100));
CREATE TABLE room_user
(
RoomId INT NOT NULL
, UserId INT NOT NULL
, CONSTRAINT PK_roomuser
PRIMARY KEY(RoomId, UserId)
, CONSTRAINT fk_room
FOREIGN KEY(RoomId)
REFERENCES dbo.rooms(id)
, CONSTRAINT fk_user
FOREIGN KEY(UserId)
REFERENCES dbo.users(id)
);
INSERT INTO dbo.users(ad)
OUTPUT
Inserted.id, Inserted.ad
VALUES('RayBoy')
, ('John')
, ('Frank');
INSERT INTO dbo.rooms(ad)
OUTPUT
Inserted.id, Inserted.ad
VALUES('Room1')
, ('Room2')
, ('Room3');
INSERT INTO dbo.room_user(RoomId, UserId)VALUES(1, 1), (1, 2), (2, 3);
-- won't allow
INSERT INTO dbo.room_user(RoomId, UserId)VALUES(999, 888);
I'm trying to write a SQL statement such that I'm reusing a return value of an insert statement as a value for following insert statement but I have no clue where to start. For example, this is my table schema (didn't write everything).
job {
job_id INT IDENTITY (1, 1) PRIMARY KEY,
start_date,
end_date,
target hours,
worker_id
FOREIGN KEY (worker_id) REFERENCES dbo.worker (worker_id)
}
worker {
worker_id INT IDENTITY (1, 1) PRIMARY KEY,
name
}
And I want to do something like this but I don't think this is the right way to do it
INSERT INTO dbo.job
VALUES(GetDate(), NULL, 8, (
INSERT INTO dbo.worker
OUTPUT
Inserted.worker_id
VALUES ('my_name')
))
Thanks in advance,
best way for your matter is
DECLARE #worker_idtbl TABLE (worker_id INT);
INSERT INTO dbo.worker OUTPUT Inserted.worker_id INTO #worker_idtbl(worker_id) VALUES ('my_name');
INSERT INTO dbo.job VALUES(GetDate(), NULL, 8, (select top 1 worker_id from #worker_idtbl) );
I have the following SQL code to create and populate a few tables in Derby:
CREATE TABLE GROUPS (
GRP_ID INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1) PRIMARY KEY,
GRP_NAME VARCHAR(256) NOT NULL,
DISPLAY_NAME VARCHAR(256));
CREATE TABLE USERS (
USR_ID INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1) PRIMARY KEY,
USR_NAME VARCHAR(256) NOT NULL,
PASSWORD VARCHAR(512) NOT NULL,
DISPLAY_NAME VARCHAR(256));
CREATE TABLE USR_GRP_MEMBERSHIP (
USR_ID INTEGER NOT NULL REFERENCES USERS ON DELETE CASCADE,
GRP_ID INTEGER NOT NULL REFERENCES GROUPS ON DELETE CASCADE,
CONSTRAINT USR_ID_GRP_ID UNIQUE (USR_ID, GRP_ID));
INSERT INTO GROUPS(GRP_NAME, DISPLAY_NAME) VALUES('Users', 'Users');
INSERT INTO GROUPS(GRP_NAME, DISPLAY_NAME) VALUES('AdminUsers', 'Administrators');
INSERT INTO USERS(USR_NAME, PASSWORD, DISPLAY_NAME) VALUES('user', 'userpwd', 'User');
INSERT INTO USERS(USR_NAME, PASSWORD, DISPLAY_NAME) VALUES('admin', 'adminpawd', 'Administrator');
#The following code populates the USR_GRP_MEMBERSHIP table using the IDs of users
#& groups inserted in the previous set of insert statements
INSERT INTO USR_GRP_MEMBERSHIP VALUES((SELECT USR_ID FROM USERS WHERE USR_NAME = 'user'), (SELECT GRP_ID FROM GROUPS WHERE GRP_NAME = 'Users'));
INSERT INTO USR_GRP_MEMBERSHIP VALUES((SELECT USR_ID FROM USERS WHERE USR_NAME = 'admin'), (SELECT GRP_ID FROM GROUPS WHERE GRP_NAME = 'Users'));
INSERT INTO USR_GRP_MEMBERSHIP VALUES((SELECT USR_ID FROM USERS WHERE USR_NAME = 'admin'), (SELECT GRP_ID FROM GROUPS WHERE GRP_NAME = 'AdminUsers'));
My Question is: The last 3 INSERT statements have the SELECT statements repeating in them. How do I store the output of those SELECT statements in a variable and use them in these 3 INSERT statements?
One way to accomplish this is to use placeholders in prepared statements?
Here's a good starting point: https://docs.oracle.com/javase/tutorial/jdbc/basics/prepared.html
Your statement would then look something like:
INSERT INTO USR_GRP_MEMBERSHIP
VALUES ((SELECT USR_ID FROM USERS WHERE USR_NAME = ?),
(SELECT GRP_ID FROM GROUPS WHERE GRP_NAME = ?));
and you would replace the placeholders with 'user'/'Users', 'admin'/'Users', 'admin'/'AdminUsers' at runtime by using SetString (twice) and then ExecuteUpdate, for each pair.
I've been trying to write this query but can't seem to get it right for some reason or another..
What I need to do is:
Change the status of a question to 'closed' if there has not been an update associated with this question inserted into the qUpdateTable in the last 24 hours.
I only want it to be closed if a staff member has replied to it at least once.
You can determine if a staff member or a user has replied to the question by checking the qUpdateTable and seeing if a the StaffID field is empty or has a value for that particular tickets updates. If there is a staffID then it has been updated by a staff member, however if it does not then the qUpdate was done by a user.
Essentialy the way this works is a user posts a question by inserting into the Question table, and replies are made by inserting into the qUpdate table and linked to the original question using the foreign key - "QuestionID".
The tables:
CREATE TABLE Staff
(
ID INTEGER NOT NULL PRIMARY KEY,
Name VARCHAR(40) NOT NULL
);
CREATE TABLE Customer
(
ID INTEGER NOT NULL PRIMARY KEY,
Name VARCHAR(40) NOT NULL,
Email VARCHAR(40) NOT NULL
);
CREATE TABLE Product
(
ID INTEGER NOT NULL PRIMARY KEY,
Name TEXT NOT NULL
);
CREATE TABLE Question
(
ID INTEGER NOT NULL PRIMARY KEY,
Problem VARCHAR(1000),
Status VARCHAR(20) NOT NULL DEFAULT 'open',
Priority INTEGER NOT NULL,
LoggedTime TIMESTAMP NOT NULL,
CustomerID INTEGER NOT NULL,
ProductID INTEGER NOT NULL,
FOREIGN KEY (ProductID) REFERENCES Product(ID),
FOREIGN KEY (CustomerID) REFERENCES Customer(ID),
CHECK (Status IN ('open','closed') AND Priority IN (1,2,3))
);
CREATE TABLE qUpdate
(
ID INTEGER NOT NULL PRIMARY KEY,
Message VARCHAR(1000) NOT NULL,
UpdateTime TIMESTAMP NOT NULL,
QuestionID INTEGER NOT NULL,
StaffID INTEGER,
FOREIGN KEY (StaffID) REFERENCES Staff(ID),
FOREIGN KEY (QuestionID) REFERENCES Question(ID)
);
Some sample inserts:
INSERT INTO Customer (ID, Name, Email) VALUES (1, 'testname1', 'testemail1');
INSERT INTO Customer (ID, Name, Email) VALUES (2, 'testname2', 'testemail2');
INSERT INTO Staff (ID, Name) VALUES (1, 'Don Keigh');
INSERT INTO Product (ID, Name) VALUES (1, 'Xbox');
INSERT INTO Question (ID, Problem, Status, Priority, LoggedTime, CustomerID, ProductID)
VALUES (1, 'testproblem1', 'open', 3, '2012-04-14 09:30', 2, 1);
INSERT INTO Question (ID, Problem, Status, Priority, LoggedTime, CustomerID, ProductID)
VALUES (2, 'testproblem2', 'open', 3, '2012-04-14 09:30', 2, 1);
INSERT INTO qUpdate (ID, Message, UpdateTime, StaffID, QuestionID) VALUES (2, 'testmessage1','2012-07-12 14:27', 1, 1);
INSERT INTO qUpdate (ID, Message, UpdateTime, QuestionID) VALUES (3, 'testmessage1','2012-06-18 19:42', 2);
What I've done so far (which obviously doesn't work)
UPDATE Question
SET Status = 'closed'
WHERE EXISTS
(SELECT qUpdate.QuestionID
MAX(qUpdate.UpdateTime - Now() = INTERVAL '1 day') FROM qUpdate
LEFT JOIN Question ON qUpdate.QuestionID = Question.ID
WHERE qUpdate.StaffID IS NOT NULL);
I realise my explanation may be a bit confusing so if you need more info post and I'll reply ASAP
UPDATE Question
SET Status = 'closed'
where
-- this clause asserts there's at least one staff answer
exists (
select null from qUpdate
where qUpdate.QuestionID = Question.ID
and StaffID is not null
)
-- this clause asserts there's been no update in the last 24 hours
and not exists (
select null from qUpdate
where qUpdate.QuestionID = Question.ID
and qUpdate.UpdateTime > (now() - interval '24 hours')
)
and Status = 'open';
You'll almost certainly want an index on qUpdate(QuestionID) or possibly qUpdate(QuestionID,UpdateTime) or qUpdate(QuestionID,StaffID) to get good performance on the subselects in the exists() tests.