Related
I am learning SQL (postgres) and am trying to insert a record into a table that references records from two other tables, as foreign keys.
Below is the syntax I am using for creating the tables and records:
-- Create a person table + insert single row
CREATE TABLE person (
pname VARCHAR(255) NOT NULL,
PRIMARY KEY (pname)
);
INSERT INTO person VALUES ('personOne');
-- Create a city table + insert single row
CREATE TABLE city (
cname VARCHAR(255) NOT NULL,
PRIMARY KEY (cname)
);
INSERT INTO city VALUES ('cityOne');
-- Create a employee table w/ForeignKey reference
CREATE TABLE employee (
ename VARCHAR(255) REFERENCES person(pname) NOT NULL,
ecity VARCHAR(255) REFERENCES city(cname) NOT NULL,
PRIMARY KEY(ename, ecity)
);
-- create employee entry referencing existing records
INSERT INTO employee VALUES(
SELECT pname FROM person
WHERE pname='personOne' AND <-- ISSUE
SELECT cname FROM city
WHERE cname='cityOne
);
Notice in the last block of code, where I'm doing an INSERT into the employee table, I don't know how to string together multiple SELECT sub-queries to get both the existing records from the person and city table such that I can create a new employee entry with attributes as such:
ename='personOne'
ecity='cityOne'
The textbook I have for class doesn't dive into sub-queries like this and I can't find any examples similar enough to mine such that I can understand how to adapt them for this use case.
Insight will be much appreciated.
There doesn’t appear to be any obvious relationship between city and person which will make your life hard
The general pattern for turning a select that has two base tables giving info, into an insert is:
INSERT INTO table(column,list,here)
SELECT column,list,here
FROM
a
JOIN b ON a.x = b.y
In your case there isn’t really anything to join on because your one-column tables have no column in common. Provide eg a cityname in Person (because it seems more likely that one city has many person) then you can do
INSERT INTO employee(personname,cityname)
SELECT p.pname, c.cname
FROM
person p
JOIN city c ON p.cityname = c.cname
But even then, the tables are related between themselves and don’t need the third table so it’s perhaps something of an academic exercise only, not something you’d do in the real world
If you just want to mix every person with every city you can do:
INSERT INTO employee(personname,cityname)
SELECT pname, cname
FROM
person p
CROSS JOIN city c
But be warned, two people and two cities will cause 4 rows to be inserted, and so on (20 people and 40 cities, 800 rows. Fairly useless imho)
However, I trust that the general pattern shown first will suffice for your learning; write a SELECT that shows the data you want to insert, then simply write INSERT INTO table(columns) above it. The number of columns inserted to must match the number of columns selected. Don’t forget that you can select fixed values if no column from the query has the info (INSERT INTO X(p,c,age) SELECT personname, cityname, 23 FROM ...)
The following will work for you:
INSERT INTO employee
SELECT pname, cname FROM person, city
WHERE pname='personOne' AND cname='cityOne';
This is a cross join producing a cartesian product of the two tables (since there is nothing to link the two). It reads slightly oddly, given that you could just as easily have inserted the values directly. But I assume this is because it is a learning exercise.
Please note that there is a typo in your create employee. You are missing a comma before the primary key.
I'm trying to wrap by brain around how to use pivot tables for a query I need. I have 3 database tables. Showing relevant columns:
TableA: Columns = pName
TableB: Columns = GroupName, GroupID
TableC: Columns = pName, GroupID
TableA contains a list of names (John, Joe, Jack, Jane)
TableB contains a list of groups with an ID#. (Soccer|1, Hockey|2, Basketball|3)
TableC contains a list of the names and the group they belong to (John|1, John|3, Joe|2, Jack|1, Jack|2, Jack|3, Jane|3)
I need to create a matrix like grid view using a SQL query that would return a list of all the names from TableA (Y-axis) and a list of all the possible groups (X-axis). The cell values would be either true or false if they belong to the group.
Any help would be appreciated. I couldn't quite find an existing answer that helped.
You might try it like this
Here I set up a MCVE, please try to create this in your next question yourself...
DECLARE #Name TABLE (pName VARCHAR(100));
INSERT INTO #Name VALUES('John'),('Joe'),('Jack'),('Jane');
DECLARE #Group TABLE(gName VARCHAR(100),gID INT);
INSERT INTO #Group VALUES ('Soccer',1),('Hockey',2),('Basketball',3);
DECLARE #map TABLE(pName VARCHAR(100),gID INT);
INSERT INTO #map VALUES
('John',1),('John',3)
,('Joe',2)
,('Jack',1),('Jack',2),('Jack',3)
,('Jane',3);
This quer will collect the values and perform PIVOT
SELECT p.*
FROM
(
SELECT n.pName
,g.gName
,'x' AS IsInGroup
FROM #map AS m
INNER JOIN #Name AS n ON m.pName=n.pName
INNER JOIN #Group AS g ON m.gID=g.gID
) AS x
PIVOT
(
MAX(IsInGroup) FOR gName IN(Soccer,Hockey,Basketball)
) as p
This is the result.
pName Soccer Hockey Basketball
Jack x x x
Jane NULL NULL x
Joe NULL x NULL
John x NULL x
Some hints:
You might use 1 and 0 instead of x as SQL Server does not know a real boolean
You should add a pID to your names. Never join tables on real data (unless it is something unique and unchangeable [which means never acutally!!!])
UPDATE dynamic SQL (thx to #djlauk)
If you want a query which deals with any amount of groups you have to to this dynamically. But please be aware, that you loose the chance to use this in ad-hoc-SQL like in VIEW or inline TVF, which is quite a big backdraw...
CREATE TABLE #Name(pName VARCHAR(100));
INSERT INTO #Name VALUES('John'),('Joe'),('Jack'),('Jane');
CREATE TABLE #Group(gName VARCHAR(100),gID INT);
INSERT INTO #Group VALUES ('Soccer',1),('Hockey',2),('Basketball',3);
CREATE TABLE #map(pName VARCHAR(100),gID INT);
INSERT INTO #map VALUES
('John',1),('John',3)
,('Joe',2)
,('Jack',1),('Jack',2),('Jack',3)
,('Jane',3);
DECLARE #ListOfGroups VARCHAR(MAX)=
(
STUFF
(
(
SELECT DISTINCT ',' + QUOTENAME(gName)
FROM #Group
FOR XML PATH('')
),1,1,''
)
);
DECLARE #sql VARCHAR(MAX)=
(
'SELECT p.*
FROM
(
SELECT n.pName
,g.gName
,''x'' AS IsInGroup
FROM #map AS m
INNER JOIN #Name AS n ON m.pName=n.pName
INNER JOIN #Group AS g ON m.gID=g.gID
) AS x
PIVOT
(
MAX(IsInGroup) FOR gName IN(' + #ListOfGroups + ')
) as p');
EXEC(#sql);
GO
DROP TABLE #map;
DROP TABLE #Group;
DROP TABLE #Name;
I suspect it may be laborious to keep the pivot up to date if categories are added. Or maybe I just prefer Excel (if you ignore one major advantage). The following approach could be helpful too, assuming you do have Office 365.
I added the three tables using 3 CREATE TABLE statements and 3 INSERT statements based on the code I saw above. (The solutions make use of temporary tables to insert specific values, but I believe you already have the data in your three tables, called TableA, TableB, TableC).
CREATE TABLE TestName (pName VARCHAR(100));
INSERT INTO TestName VALUES('John'),('Joe'),('Jack'),('Jane');
CREATE TABLE TestGroup (gName VARCHAR(100),gID INT);
INSERT INTO TestGroup VALUES ('Soccer',1),('Hockey',2),('Basketball',3);
CREATE TABLE Testmap (pName VARCHAR(100),gID INT);
INSERT INTO Testmap VALUES
('John',1),('John',3)
,('Joe',2)
,('Jack',1),('Jack',2),('Jack',3)
,('Jane',3);
Then, in MS Excel, I added (there may be a shorter sequence but I'm still exploring) the three tables as queries from database > sql server database. After adding them, I added all three to the Data Model (I can elaborate if you ask).
I then inserted PivotTable from the ribbon, chose External data source, but opened the Tables tab (instead of Connections tab), to find my data model (mine was top of the list) and I clicked Open. At some point Excel prompted me to create relationships between tables and it did a good job of auto generating them for me.
After minor tweaks my PivotTable came out like this (I could also ask Excel to show the data as a PivotChart).
Pivot showing groups as columns and names as rows.
The advantage is that you don't have to revisit the PIVOT code in SQL if the list (of groups) changes. As I think someone else mentioned, consider using ids for pName as well, or another way to ensure that you are not stuck the next day if you have two persons named John or Jack.
In Excel you can choose when to refresh the data (or the pivot) and, after refresh, any additional categories will be added and counted.
insert into Orders values ('1111',
(Select CustomerID from Customers where CustomerID = (Select CustomerID from customers where CompanyName= 'erp')),
(Select EmployeeID from Employees where EmployeeID = (Select EmployeeID from Employees where FirstName = 'Hello')),
(Select ShipperID from Shippers Where ShipperID = (Select ShipperID from Shippers where CompanyName= 'Ntat')),
'2014-12-01','2013-12-01','22','22','aa','aa','dd','gs','ga','ga','qq');
i am unable to run this Query as i m getting error :
Error Code: 1242. Subquery returns more than 1 row
Kindly help
The INSERT command comes in two flavors:
(1) either you have all your values available, as literals or SQL Server variables - in that case, you can use the INSERT .. VALUES() approach:
INSERT INTO dbo.YourTable(Col1, Col2, ...., ColN)
VALUES(Value1, Value2, #Variable3, #Variable4, ...., ValueN)
Note: I would recommend to always explicitly specify the list of column to insert data into - that way, you won't have any nasty surprises if suddenly your table has an extra column, or if your tables has an IDENTITY or computed column. Yes - it's a tiny bit more work - once - but then you have your INSERT statement as solid as it can be and you won't have to constantly fiddle around with it if your table changes.
(2) if you don't have all your values as literals and/or variables, but instead you want to rely on another table, multiple tables, or views, to provide the values, then you can use the INSERT ... SELECT ... approach:
INSERT INTO dbo.YourTable(Col1, Col2, ...., ColN)
SELECT
SourceColumn1, SourceColumn2, #Variable3, #Variable4, ...., SourceColumnN
FROM
dbo.YourProvidingTableOrView
Here, you must define exactly as many items in the SELECT as your INSERT expects - and those can be columns from the table(s) (or view(s)), or those can be literals or variables. Again: explicitly provide the list of columns to insert into - see above.
You can use one or the other - but you cannot mix the two - you cannot use VALUES(...) and then have a SELECT query in the middle of your list of values - pick one of the two - stick with it.
For more details and further in-depth coverage, see the official MSDN SQL Server Books Online documentation on INSERT - a great resource for all questions related to SQL Server!
TL;DR
There is a design integrity issue with your application, from which you will not be able to recover at a Sql Query level.
In Detail
Using non-key values to lookup foreign keys during an insert is not a great idea, as you've now found - the error message indicates that one or more of the subqueries has matched multiple rows, and now you are faced with an idempotence issue.
e.g. Lets just say that in this instance, you have more than one Employee with the name 'Hello'. Your options appear to be:
Either attribute the order to the FIRST employee with the name 'Hello' - obviously this is potentially unfair to the real employee who made the sale
Insert multiple orders, one for each employee - but now we risk double shipping and billing issues.
So the real solution is to ensure that you carry all of the key fields (either a Primary or Unique Key, whether natural or surrogate) for each of the FK role columns through your application at all times.
This then means that you can insert the data with confidence
insert into Orders values ('1111',
#CustomerId,
#EmployeeId,
#ShipperId,
'2014-12-01','2013-12-01','22','22','aa','aa','dd','gs','ga','ga','qq');
You will have to do this thing with the help of procedure because you are getting more than one value in select statement....
You will have to pass value one by one in insert statement
create procedure test
as
declare #customerid int
declare #empid int
declare #shipperid int
begin
set #customerid= (Select CustomerID from customers where CompanyName='erp')
set #empid=(Select EmployeeID from Employees where FirstName = 'Hello')
set #shipperid =(Select ShipperID from Shippers where CompanyName='Ntat')
-- but note down that it will assign last value to variable
-- but if it returns more than one value you will have to create a temporary table and --then assign value to it and will have to apply loop
-- like this create #temp1 (customerid id)
insert into orders values(#customerid,#smpid,#shipperid,'val1','val2'...ans so one)
end
I have a table containing data that i need to migrate into another table with a linking table. This is a one time migration as part of an upgrade.
I have a company table that contains records relating to a company and a contact person.
I want to migrate the contact details into another table and link the new person with a linking table
Consider I have this table which is already populated
tblCompany
CompanyId
CompanyName
RegNo
ContactForename
ContactSurname
And i want to migrate the contact person data to
tblPerson
PersonID (identitycolumn)
Forename
Surname
and use the identity column resulting and insert it into the linking table
tblCompanyPerson
CompanyId
PersonId
I've tried a few different ways to approach this using cursors and output variables into a temp table but none seem right to me (or give me the solution...)
The closest i have got is to have a companyID on tblPerson and insert companyId into it and output the new personId and the companyId into a temp table. Then loop through the temp table to create the tblCompanyContact.
example
declare #companycontact TABLE (companyId int, PersonId int)
insert into tblPerson
(Forename,
Surname,
CompanyID)
output inserted.CompanyID, INSERTED.PersonID into #companycontact
select
ContactPersonForeName,
ContactPersonSurename,
CompanyID
from tblCompany c
insert into tblCompanyPerson
(CompanyID,
PersonID)
select c.companyId, PersonId from #companycontact c
Background
Im using MS SQL Server 2008 R2
The tblPerson is already populated with hundreds of thousands of
records.
There is a 'trick' using MERGE statement to achieve mapping between newly inserted and source values:
MERGE tblPerson trgt
USING tblCompany src ON 1=0
WHEN NOT MATCHED
THEN INSERT
(Forename, Surename)
VALUES (src.ContactPersonForeName, src.ContactPersonSurename)
OUTPUT src.CompanyID, INSERTED.PersonID
INTO tblCompanyPerson (CompanyId, PersonID);
That 1=0 condition is to always get everything from source. You might want to replace it or even whole source with some sub-query to actually check whatever you already have same person mapped.
EDIT: Here is some reading about using MERGE and OUTPUT
Because I don't know what SQL you are using its difficult to decide if this is correct. i also don't know if you already tried this but it's the best idea i have:
insert into tblPerson
(Forename, Surename)
Select ContactForename, ContactPersonSurename
from tblCompany
insert into tblCompanyPerson
(CompanyID, PersonID)
select CompanyId, PersonID
from tblPerson, tblCompany
where ContactForename = Forename and ContactPersonSurename = Surename
Sarajog
I know I am sounding dumb but I really need help on this.
I have a Table (let's say Meeting) which Contains a column Participants.
The Participants dataType is varchar(Max) and it stores Participant's Ids in comma separated form like 1,2.
Now my problem is I am passing a parameter called #ParticipantsID in my Stored Procedure and want to do something like this:
Select Participants from Meeting where Participants in (#ParticipantsID)
Unfortunately I am missing something crucial here.
Can some one point that out?
I've been there before... I changed the DB design to have one record contain a single reference to the other table. If you can't change your DB structures and you have to live with this, I found this solution on CodeProject.
New Function
IF EXISTS(SELECT * FROM sysobjects WHERE ID = OBJECT_ID(’UF_CSVToTable’))
DROP FUNCTION UF_CSVToTable
GO
CREATE FUNCTION UF_CSVToTable
(
#psCSString VARCHAR(8000)
)
RETURNS #otTemp TABLE(sID VARCHAR(20))
AS
BEGIN
DECLARE #sTemp VARCHAR(10)
WHILE LEN(#psCSString) > 0
BEGIN
SET #sTemp = LEFT(#psCSString, ISNULL(NULLIF(CHARINDEX(',', #psCSString) - 1, -1),
LEN(#psCSString)))
SET #psCSString = SUBSTRING(#psCSString,ISNULL(NULLIF(CHARINDEX(',', #psCSString), 0),
LEN(#psCSString)) + 1, LEN(#psCSString))
INSERT INTO #otTemp VALUES (#sTemp)
END
RETURN
END
Go
New Sproc
SELECT *
FROM
TblJobs
WHERE
iCategoryID IN (SELECT * FROM UF_CSVToTable(#sCategoryID))
You would not typically organise your SQL database in quite this way. What you are describing are two entities (Meeting & Participant) that have a one-to-many relationship. i.e. a meeting can have zero or more participants. To model this in SQL you would use three tables: a meeting table, a participant table and a MeetingParticipant table. The MeetingParticipant table holds the links between meetings & participants. So, you might have something like this (excuse any sql syntax errors)
create table Meeting
(
MeetingID int,
Name varchar(50),
Location varchar(100)
)
create table Participant
(
ParticipantID int,
FirstName varchar(50),
LastName varchar(50)
)
create table MeetingParticipant
(
MeetingID int,
ParticipantID int
)
To populate these tables you would first create some Participants:
insert into Participant(ParticipantID, FirstName, LastName) values(1, 'Tom', 'Jones')
insert into Participant(ParticipantID, FirstName, LastName) values(2, 'Dick', 'Smith')
insert into Participant(ParticipantID, FirstName, LastName) values(3, 'Harry', 'Windsor')
and create a Meeting or two
insert into Meeting(MeetingID, Name, Location) values(10, 'SQL Training', 'Room 1')
insert into Meeting(MeetingID, Name, Location) values(11, 'SQL Training', 'Room 2')
and now add some participants to the meetings
insert into MeetingParticipant(MeetingID, ParticipantID) values(10, 1)
insert into MeetingParticipant(MeetingID, ParticipantID) values(10, 2)
insert into MeetingParticipant(MeetingID, ParticipantID) values(11, 2)
insert into MeetingParticipant(MeetingID, ParticipantID) values(11, 3)
Now you can select all the meetings and the participants for each meeting with
select m.MeetingID, p.ParticipantID, m.Location, p.FirstName, p.LastName
from Meeting m
join MeetingParticipant mp on m.MeetingID=mp.MeetingID
join Participant p on mp.ParticipantID=p.ParticipantID
the above should produce
MeetingID ParticipantID Location FirstName LastName
10 1 Room 1 Tom Jones
10 2 Room 1 Dick Smith
11 2 Room 2 Dick Smith
11 3 Room 2 Harry Windsor
If you want to find out all the meetings that "Dick Smith" is in you would write something like this
select m.MeetingID, m.Location
from Meeting m join MeetingParticipant mp on m.MeetingID=mp.ParticipantID
where
mp.ParticipantID=2
and get
MeetingID Location
10 Room 1
11 Room 2
I have omitted important things like indexes, primary keys and missing attributes such as meeting dates, but it is clearer without all the goo.
Your table is not normalized. If you want to query for individual participants, they should be split into their own table, along the lines of:
Meeting
MeetingId primary key
Other stuff
Persons
PersonId primary key
Other stuff
Participants
MeetingId foreign key Meeting(MeetingId)
PersonId foreign key Persons(PersonId)
primary key MeetingId,PersonId
Otherwise, you have to resort to all sorts of trickery (what I call SQL gymnastics) to find out what you want. That trickery never scales well - your queries become slow very quickly as the table grows.
With a properly normalized database, the queries can remain fast well into the multi-millions of records (I work with DB2/z where we are used to truly huge tables).
There are valid reasons for sometimes reverting to second normal form (or even first) for performance but that should be a very hard thought out decision (and based on actual performance data). All databases should initially start of in 3NF.
SELECT * FROM Meeting WHERE Participants LIKE '%,12,%' OR Participants LIKE '12,%' OR Participants LIKE '%,12'
where 12 is the ID you are looking for....
Ugly, what a nasty model.
If I understand your question correctly, you are trying to pass in a comma separated list of participant ids and see if it is in your list. This link lists several ways to do such a thing"
[http://vyaskn.tripod.com/passing_arrays_to_stored_procedures.htm][1]
codezy.blogspot.com
If you store the participant ids in a comma-separated list (as text) in the database, you cannot easily query it (as a list) using SQL. You would have to resort to string-operations.
You should consider changing your schema to use another table to map meetings to participants:
create table meeting_participants (
meeting_id integer not null , -- foreign key
participant_id integer not null
);
That table would have multiple rows per meeting (one for each participant).
You can then query that table for individual participants, or number of participants, and such.
If participants is a separate data type you should be storing it as a child table of your meeting table. e.g.
MEETING
PARTICIPANT 1
PARTICIPANT 2
PARTICIPANT 3
Each participant would hold the meeting ID so you can do a query
SELECT * FROM participants WHERE meeting_id = 1
However, if you must store a comma separated list (for some external reason) then you can do a string search to find the appropriate record. This would be a very inefficient way to do a query though.
That is not the best way to store the information you have.
If it is all you have got then you need to be doing a contains (not an IN). The best answer is to have another table that links Participants to Meetings.
Try SELECT Meeting, Participants FROM Meeting CONTAINS(Participants, #ParticipantId)