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) );
Related
I have created table like below:
create table EmployeeDetails
(
id int,
name varchar(50),
designation varchar(50),
ReportingTo int
)
And inserted rows like this:
insert into EmployeeDetails values(1, 'A', 'Developer', 3)
insert into EmployeeDetails values(5, 'E', 'CEO', 5)
insert into EmployeeDetails values(2, 'B', 'Developer', 3)
insert into EmployeeDetails values(3, 'C', 'Manager', 4)
insert into EmployeeDetails values(4, 'D', 'S.Manager', 5)
My question is: how can I identify the last inserted row in the table?
Used queries:
select IDENT_CURRENT('EmployeeDetails')
Select SCOPE_IDENTITY()
But I still didn't find the answer.
Replies are always welcome
You have a fundamental misunderstanding of tables in relational databases. They represent unordered sets. So, there is no "last row" in a table. The information on the ordering of rows has to be included when you create the table and/or load data into it.
In SQL Server, the simplest method is an identity column. That is why many tables are defined as:
create table EmployeeDetails (
id int identity primary key,
name varchar(50),
designation varchar(50),
ReportingTo int
);
You can also add default insertion time columns:
create table EmployeeDetails (
id int identity primary key,
name varchar(50),
designation varchar(50),
ReportingTo int,
CreatedAt datetime default gettime()
);
However, you can have multiple rows with the same datetime value.
You also can use rowversion like below,if you add a column
CREATE TABLE MyTest (myKey int
,myValue int, RV rowversion);
GO
INSERT INTO MyTest (myKey, myValue) VALUES (1, 0);
GO
INSERT INTO MyTest (myKey, myValue) VALUES (2, 0);
select * from mytest order by rv desc
Note:
This always give the last row inserted/Updated
References:
rowversion
Add fields of type datetime with name CreateDate and UpdateDate in your table, when you insert record in your table set their value for getdate()
After that you can run queries:
Select top 10 * from YourTable Order By CreateDate DESC
Or for last updated
Select top 10 * from YourTable Order By UpdateDate DESC
Please find my answer as below. Hope this may help you.
Add one more column to store record creation date/time as below.
create table EmployeeDetails
(
id int,
name varchar(50),
designation varchar(50),
ReportingTo int,
CreatedOn datetime
)
After table creation and inserting records write/execute query (here inner query is used) as below
select
*
from EmployeeDetails
where CreatedOn = (select max(CreatedOn) from EmployeeDetails )
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
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.
My table structure looks like this:
create table rankings (
id IDENTITY NOT NULL,
user_id INT NOT NULL,
game_poule_id INT NOT NULL,
rank INT NOT NULL,
insertDate DATETIME NOT NULL,
FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE,
FOREIGN KEY (game_poule_id) REFERENCES game_poules(id) ON DELETE CASCADE
);
All old rankings of users per game are saved in this table. Now I want to have the last but one rank in the table for all users in a gamepoule.
Has someone an idea how to achive this? Thanks
You need to self join the table to get the records you require.
For this answer I created your table without the foreign keys as they are not required to get it to work.
CREATE TABLE Rankings (
id int IDENTITY NOT NULL,
user_id INT NOT NULL,
game_poule_id INT NOT NULL,
rank INT NOT NULL,
insertDate DATETIME NOT NULL
);
Insert some sample data. Without more information I cannot simulate any better than this.
INSERT Rankings(user_id,game_poule_id,rank,insertDate)
VALUES(1, 100, 3, CURRENT_TIMESTAMP-2)
INSERT Rankings(user_id,game_poule_id,rank,insertDate)
VALUES(1, 100, 2, CURRENT_TIMESTAMP-1)
INSERT Rankings(user_id,game_poule_id,rank,insertDate)
VALUES(1, 101, 6, CURRENT_TIMESTAMP)
INSERT Rankings(user_id,game_poule_id,rank,insertDate)
VALUES(2, 100, 5, CURRENT_TIMESTAMP-2)
INSERT Rankings(user_id,game_poule_id,rank,insertDate)
VALUES(2, 100, 1, CURRENT_TIMESTAMP-1)
INSERT Rankings(user_id,game_poule_id,rank,insertDate)
VALUES(2, 101, 2, CURRENT_TIMESTAMP)
Query for the last but one rank
SELECT Rankings.game_poule_id, Rankings.user_id, rank, MAX(Rankings.insertDate)
FROM Rankings INNER JOIN
(SELECT game_poule_id, user_id, MAX(insertDate) max_insert_date
FROM rankings
GROUP BY game_poule_id, user_id) Max_Ranking_Date
ON Rankings.user_id = Max_Ranking_Date.user_id
AND Rankings.insertDate < Max_Ranking_Date.max_insert_date
AND Rankings.game_poule_id = Max_Ranking_Date.game_poule_id
GROUP BY Rankings.game_poule_id, Rankings.user_id, rank
PLEASE NOTE!
As you can see from the results you will not get a ranking for a game that only has one row per user. But since you are asking for the "last but one" that only makes sense for games with multiple entries.
EDIT:
I've just realised the query I have provided will not return one row per user per game. Anyone want to fix it? I have to get on with some work :)
Another possible (not very nice) solution
SELECT
*
FROM
rankings r
WHERE
FK_gamePoule = 0 AND
r.insertDate = COALESCE(
(SELECT
r2.insertDate
FROM
rankings r2
WHERE
r.FK_user = r2.FK_user ORDER BY r2.insertDate DESC
LIMIT 1
OFFSET 1), '2048-12-31 23:59:59')
Is it possible to create a Database which has 1 column (but not the column of primary key) to be auto-increment? So that when I insert value to the database, i don't need to fill in the value myself, and DB will fill in that value for that column for me (and increment every time I do a new insert)?
Thank you.
Yes, of course it is possible. Just make this column a unique key (not a primary key) and it has to be declared with a special attribute: "IDENTITY" for SQL Server, and
"AUTO_INCREMENT" for MySQL (see the example below) . And another column can be a primary key.
On MySQL database the table could be declared like this:
CREATE TABLE `mytable` (
`Name` VARCHAR(50) NOT NULL,
`My_autoincrement_column` INTEGER(11) NOT NULL AUTO_INCREMENT,
PRIMARY KEY (`Name`),
UNIQUE KEY `My_autoincrement_column` (`My_autoincrement_column`)
);
Yes, you can do this. Here is a sample for SQL Server using IDENTITY:
CREATE TABLE MyTable (
PrimaryKey varchar(10) PRIMARY KEY,
IdentityColumn int IDENTITY(1,1) NOT NULL,
DefaultColumn CHAR(1) NOT NULL DEFAULT ('N')
)
INSERT INTO MyTable (PrimaryKey) VALUES ('A')
INSERT INTO MyTable (PrimaryKey) VALUES ('B')
INSERT INTO MyTable (PrimaryKey, DefaultColumn) VALUES ('C', 'Y')
INSERT INTO MyTable (PrimaryKey, DefaultColumn) VALUES ('D', 'Y')
INSERT INTO MyTable (PrimaryKey, DefaultColumn) VALUES ('E', DEFAULT)
--INSERT INTO MyTable (PrimaryKey, DefaultColumn) VALUES ('F', NULL) -- ERROR
--> Cannot insert the value NULL into column 'DefaultColumn', table 'tempdb.dbo.MyTable'; column does not allow nulls. INSERT fails.
SELECT * FROM MyTable
Here is an example using SQL Server using functions to roll-your-own incrementing column. This is by means not fault tolerant or the way I would do it. (I'd use the identity feature.) However, it is good to know that you can use functions to return default values.
DROP TABLE MyTable
GO
DROP FUNCTION get_default_for_mytable
GO
CREATE FUNCTION get_default_for_mytable
()
RETURNS INT
AS
BEGIN
-- Declare the return variable here
DECLARE #ResultVar int
-- Add the T-SQL statements to compute the return value here
SET #ResultVar = COALESCE((SELECT MAX(HomeBrewedIdentityColumn) FROM MyTable),0) + 1
-- Return the result of the function
RETURN #ResultVar
END
GO
CREATE TABLE MyTable (
PrimaryKey varchar(10) PRIMARY KEY,
IdentityColumn int IDENTITY(1,1) NOT NULL,
DefaultColumn CHAR(1) NOT NULL DEFAULT ('N'),
HomeBrewedIdentityColumn int NOT NULL DEFAULT(dbo.get_default_for_mytable())
)
GO
INSERT INTO MyTable (PrimaryKey) VALUES ('A')
INSERT INTO MyTable (PrimaryKey) VALUES ('B')
INSERT INTO MyTable (PrimaryKey, DefaultColumn) VALUES ('C', 'Y')
INSERT INTO MyTable (PrimaryKey, DefaultColumn) VALUES ('D', 'Y')
INSERT INTO MyTable (PrimaryKey, DefaultColumn) VALUES ('E', DEFAULT)
--INSERT INTO MyTable (PrimaryKey, DefaultColumn) VALUES ('F', NULL) -- ERRROR
--> Cannot insert the value NULL into column 'DefaultColumn', table 'tempdb.dbo.MyTable'; column does not allow nulls. INSERT fails.
SELECT * FROM MyTable
Results
PrimaryKey IdentityColumn DefaultColumn HomeBrewedIdentityColumn
---------- -------------- ------------- ------------------------
A 1 N 1
B 2 N 2
C 3 Y 3
D 4 Y 4
E 5 N 5
I think you can have only 1 identity autoincrement column per table, this columns doesn't have to be the primary key but it would mean you have to insert the primary key yourself.
If you already have a primary key which is auto increment then I would try and use this if possible.
If you are trying to get an row ID to range on for querying then I would look at creating a view which has the row ID in it (not SQL 2000 or below).
Could you add in what your primary key is and what you intend to use the auto increment column for and it might help come up with a solution
On sql server this is called an identity column
Oracle and DB2 have sequence but I think you are looking for identity and all major dbms (mysql, sql server, db2, oracle) support it.