Transact SQL :: Left Join To Get Info From A Table With Foreign Keys
Sep 13, 2015
I am still new to SQL and I am having trouble obtaining the results I need from a query. I have worked on this command for some time and searched the internet but cannot seem to still get it correct.
I have a table called Patient. It's primary key is pat_id.
I have a second table called Coverage. It has no primary key. The foreign keys are pat_id, coverage_plan_id, and hosp_status.
I have a third table called Coverage_History. It has a primary key consisting of pat_id, hosp_status, copay_priority, and effective_from.
I want to get the pat_id and all the coverage information that is current. The coverage table contains specific insurance policy information. The coverage_history table will indicate the effective dates for the coverage. So the tables could contain something like this:
Patient (pat_id and lname)
P123 Monto
P124 Minto
P125 Dento
P126 Donto
Coverage (pat_id, coverage_plan_id, hosp_status, policy_num)
P123 MED1 OP A1499
P123 ACT4 OP H39B
P124 MED1 OP C90009
P124 RAC OP 99KKKK
P124 RAC OP 99KKKK
P124 MED1 OP C90009
P125 ARP OP G190
P126 BCB OP H88
Coverage_History (pat_id, hosp_status, copay_priority, effective_from, coverage_plan_id, effective_to)
P123 OP 1 20150102 MED1 NULL
P123 OP 2 20150102 ACT4 NULL
P124 OP 1 20150203 RAC 20150430
P124 OP 2 20150203 MED1 20150430
P124 OP 1 20150501 MED1 NULL
P124 OP 2 20150501 RAC NULL
P125 OP 1 20150801 ARP NULL
P126 OP 1 20150801 BCB 20160101
select p.pat_id, p.lname, ch.coverage_plan_id, ch.hosp_status, ch.effective_from, ch.effective_to, ch.copay_priority,
from patient p
left join
( coverage_history ch left join coverage c on ch.coverage_plan_id = c.coverage_plan_id and ch.patient_id = c.patient_id and
(ch.effective_to is NULL or ch.effective_to >= getdate()
)
) on ch.patient_id = p.patient_id
where ( ch.effective_to is NULL or ch.effective_to >= getdate() )
So I want to see:
P123 Monto MED1 OP 20150102 NULL 1
P123 Monto ACT4 OP 20150102 NULL 2
P124 Minto MED1 OP 20150501 NULL 1
P124 Minto RAC OP 20150501 NULL 2
P125 Dento ARP OP 20150801 NULL 1
P126 Donto BCB OP 20150801 20160101 1
I've attempted to identify a primary and foreign key in these two tables, but I am getting a bunch of errors re duplicate keys and column names needing to be unique.Perhaps the primary and foreign key I have identified don't meet the criteria?
CREATE TABLE StockNames ( -- Added Primary key to [stock_symbol] [stock_symbol] VARCHAR(5) NOT NULL CONSTRAINT PK_stock_symbol PRIMARY KEY, [stock_name] VARCHAR(150) NOT NULL, [stock_exchange] VARCHAR(50) NOT NULL,
I was writing a query using both left outer join and inner join. And the query was ....
SELECT S.companyname AS supplier, S.country,P.productid, P.productname, P.unitprice,C.categoryname FROM Production.Suppliers AS S LEFT OUTER JOIN (Production.Products AS P INNER JOIN Production.Categories AS C
[code]....
However ,the result that i got was correct.But when i did the same query using the left outer join in both the cases
i.e..
SELECT S.companyname AS supplier, S.country,P.productid, P.productname, P.unitprice,C.categoryname FROM Production.Suppliers AS S LEFT OUTER JOIN (Production.Products AS P LEFT OUTER JOIN Production.Categories AS C ON C.categoryid = P.categoryid) ON S.supplierid = P.supplierid WHERE S.country = N'Japan';
The result i got was same,i.e
supplier country productid productname unitprice categorynameSupplier QOVFD Japan 9 Product AOZBW 97.00 Meat/PoultrySupplier QOVFD Japan 10 Product YHXGE 31.00 SeafoodSupplier QOVFD Japan 74 Product BKAZJ 10.00 ProduceSupplier QWUSF Japan 13 Product POXFU 6.00 SeafoodSupplier QWUSF Japan 14 Product PWCJB 23.25 ProduceSupplier QWUSF Japan 15 Product KSZOI 15.50 CondimentsSupplier XYZ Japan NULL NULL NULL NULLSupplier XYZ Japan NULL NULL NULL NULL
and this time also i got the same result.My question is that is there any specific reason to use inner join when join the third table and not the left outer join.
I have an issue where i am mandated to enforce RI on an applications database (a good thing). but I have several common lookup tables where many of the "codes" reside for many different code types. I also have the mandate that i cannot change the underlying DDL to make composite keys to match the codes table PK. I am currently looking at creating indexed views on top of the Codes table to seperate the logical tables it contains. This is several hundred views.
I do know that I do not want to write several hundred triggers to enforce RI. Table schema below, the CdValue column is the column that is used throughout the hundreds of tables that use this codes table, and their corresponding column is not named the same.
CREATE TABLE dbo.CodesTable ( PartyGrpId INT NOT NULL , CdTyp VARCHAR ( 8 ) NOT NULL , CompId INT NOT NULL , CdValue VARCHAR ( 8 ) NOT NULL , CdValueDesc VARCHAR ( 255 ) NULL , AltValueDesc VARCHAR ( 100 ) NULL
[Code] ....
I did though run into one forum where a person brought up a great idea. Filtered Foreign Keys, what a novel concept, if it could work it would make so much less code to fix an issue like this.
ALTER TABLE dbo.BusinessStatus WITH NOCHECK ADD CONSTRAINT FK_dbo_BusinessStatus_CodesTable FOREIGN KEY (LoanStsDtCd) REFERENCES dbo.CodesTable (CdValue) WHERE CdTyp = 'Status'
I am using stored procedure to load gridview but problem is that i am not getting all rows from first table[ Subject] on applying conditions on second table[ Faculty_Subject table] ,as you can see below if i apply condition :-
Faculty_Subject.Class_Id=@Class_Id
Then i don't get all subjects from subject table, how this can be achieved.
Sql Code:- GO ALTER Proc [dbo].[SP_Get_Subjects_Faculty_Details] @Class_Id int AS BEGIN
I'm going through my tables and rewriting them so that I can create relationship-based constraints and create foreign keys among my tables. I didn't have a problem with a few of the tables but I seem to have come across a slightly confusing hiccup.
Here's the query for my Classes table:
Code:
CREATE TABLE Classes ( class_id INT IDENTITY PRIMARY KEY NOT NULL,
This statement runs without problems and I Create the relationship with my Users table just fine, having renamed it to teacher_id. I have a 1:n relationship between users and tables AND an n:m relationship because a user can be a student or a teacher, the difference is one field, user_type, which denotes what type of user a person is. In any case, the relationship that's 1:n from users to classes is that of the teacher instructing the class. The problem exists when I run my query for the intermediary table between the class and the gradebook:
Code:
CREATE TABLE Classes_have_Grades ( class_id INT PRIMARY KEY NOT NULL,
Query Analyzer spits out: Quote: Originally Posted by Query Analyzer There are no primary or candidate keys in the referenced table 'Classes' that match the referencing column list in the foreign key 'Classes_have_gradesFKIndex2'. Now, I know in SQL Server 2000 you can only have one primary key. Does that mean I can have a multi-columned Primary key (which is in fact what I would like) or does that mean that just one field can be a primary key and that a table can have only the one primary key?
In addition, what is a "candidate" key? Will making the other fields "Candidate" keys solve my problem?
I have a database column that stores a comma delimited list of foreignkeys. Would someone show me how to do a join using the values from alist stored within a record?For example, a record in tbl_cds.genre_id might have a value of "2,5, 6" corresponding to genre_ids 2 , 5 and 6. I want to jointbl_cds.genre_id to tbl_genre.genre_id using the values in that datafield.It seems I need a loop like this:SELECT * FROM tbl_cdsWHEREBegin Looptbl_cds.genre_id[i] = tbl_genre.genre_idEnd Loop.Would someone give me the correct syntax?Is there an alternative method that would create less overhead?Sorry for such a novice post.
suppose if we do not have FK then what kind of advantage we could not avail. we can fetch data from two table by creating a relation in sql.....then why FK is required.
I have question about the size of foreign key’s in sql-server 2012. If I in one table had a foreign key of the “INT” type. Do it still cost 4 bytes of storage?
SELECT A.EmpId,A.IncidentDate FROM EmployeePoints1 as A WHERE IncidentDate= (SELECT MAX(IncidentDate) FROM EmployeePoints1 WHERE EmpId = A.EmpId) AND (DATEADD(day,28,DATEADD(WEEK, DATEDIFF(WEEK, 0,A.IncidentDate), 0)) < DATEADD(WEEK, DATEDIFF(WEEK, 0,GetDate()), 0)) AND (A.IncidentCode = 'I' OR A.IncidentCode = 'A') LEFT JOIN EmployeeTotalPoints1 ON EmployeeTotalPoints1.EmpId = A.EmpId
There is itemlookup table, which stores item number and itemdescription. Also there is a child table, pricehistory, of theitemlookup table, which stores different prices and different dateranges. So it is one-to-many relationship. (Price can be stored morethan one with a different date range)And there is another table RequestItem that stores the foreign key ofthe itemlookup table to show the information of the itemlookup table.Then how do I know later which date range of the price was stored inthe RequestItem table? Since I only keep the foreign key of theitemlookup table, it will be impossible to keep track of the row of thepricehistory table if there are more than one data existed in thepricehistory table.Will it be a valid table structure to create a column for the foreignkey of the pricehistory in RequestItem table or any other ways tohandle this issue?
I have a query that based 2 tables. I wrote a query with a left join on the base table but the result set returns multiple rows for each occurrence in the second table because of the left join. I want but to return all records from on table A and only matching records from table B which id but I would wan tit to keep return them vertically as the because it make it difficult to read when put in a spreadsheet. It want it to return the values horizontally so the rows are not increasing for each occurrence on table b.
SELECT U.UserFamilyName, F.FamilyName FROM Users U LEFT JOIN User_Friends F ON U.UserID = F.UserID WHERE U.UserName = ‘JOHN’
How do I adjust my query to select just the very first record from Users_friends, I want only the top first one.And if there are no friends how can I return an empty string instead of Null.
SELECT * FROM a LEFT OUTER JOIN b ON a.id = b.id instead of
SELECT * FROM a LEFT JOIN b ON a.id = b.id
generates a different execution plan?
My query is more complex, but when I change "LEFT OUTER JOIN" to "LEFT JOIN" I get a different execution plan, which is absolutely baffling me! Especially considering everything I know and was able to research essentially said the "OUTER" is implied in "LEFT JOIN".
I have two tables as below. I want to update a quote and change the item for which it is for. So I want to do an update statement to change the cat_ref that the quote is for. However, when I do this I get a foreign key conflict with cat_ref in the item table. How do I get around this? Thanks
I have a very elementary question on table design. This screenshot (which is part of a larger diagram) sets the context of the question.
There are two distinct groups of products with different attributes, hence two separate tables: Products_A and Products_B. There's a third table that keeps track of daily production (DailyProduction), which must accept items from either product table. Now, my question is: How do I relate these two tables to "DailyProduction" ? If I place a double-constraint with two foreign keys, then I get an error whenever I attempt to insert a record in DailyProduction. For example, if the new item is of "Products_A" type, then the error message from SSMS is:
No row was updated.
The data in row 1 was not committed. Error Source: .Net SqlClient Data Provider. Error Message: The INSERT statement conflicted with the FOREIGN KEY constraint "FK_DailyProduction_Products_B". The conflict occurred in database "MyDatabase", table "dbo.Products_B", column 'ProductB_ID'. The statement has been terminated.
Correct the errors and retry or press ESC to cancel the change(s).
It's clear that the error message makes sense as SQL is trying to apply BOTH constraints. It's one AND the other, not one OR the other. Now, how do I remedy this ? What would be the most appropriate way to relate the three tables ?
We have a service that inserts some rows into a parent table (P) and child table (C). This operation is atomic and performed within a transaction.
We also have a service that queries these tables such that rows are (should only be) returned from P where there are no children for that parent.
The SQL that performs this is simplified below:
SELECT P.SomeCol FROM P LEFT OUTER JOIN C ON P.PKofP_Value = C.PkofP_Value WHERE C.PkofPValue IS NULL AND P.SomeOtherCol=0
Our expectation is that the query service should only return rows from P where there are no rows in C.
However, this seems not to be the case, and occasionally we find that rows from P are returned where there are matching rows in C.
We are sure that the process that inserts rows into P and C does so within a single transaction.
We have traced this with SQLTrace and can see the txn stag and committing and all operations using the same transactionid within the transaction.
We are running the default isolation level committed.
In SQLTrace we can see the query process start, the inserter process start and complete and then the query process continue (after presumably being blocked).
So how can the query process "miss" the child rows and return the parent from the above query?
Is it possible that, in this isolation level, the inserter process can block the query process such that when the inserter process commits and when the query process continues it does not see the child rows inserted because they were inserted in the table/index "behind" where the query process has already read - some kind of phantom phenomenon?
i'm using sql express, management studio express and a visual web developer starter kit. i have 4 tables: items; categories; categorization; old_items the old_items table has both the item id and category fields in it, the new db has them separated: items.id; categories.id; categorization.itemId, categorizaton.parentCategoryId, both of which are foreign keys. i need to get the old_item.id and old_item.category values into the new categorization table but it keeps choking on the foreign keys and i can't get past it. as far as i've been able to figure out so far, i need to turn off the foreign keys to do the insert but i'm not sure and i haven't been able to find any sql query examples that demonstrate it or explain it well enough for my n00b self. i've read http://msdn.microsoft.com/en-us/library/10cetyt6.aspx, "How to: Disable Foreign Key Constraints with INSERT and UPDATE Statements" but i don't get how that affects it, it seems like one of the other options would actually disable them. can anyone help? i've been trying all the permutations of queries i can think of and not getting it. thanks.
Kinda new to SQL, using SQL Server 2005.I have some foreign keys in a couple of tables. I need to drop thesetables, but can't since I'll get the error:Msg 3726,Level 16, State 1, Line 1Could not drop object 'Client' because it is referenced by a FOREIGNKEY constraint.I'm not sure how to disable or get rid of these foreign keys so that Ican drop my tables. I tried:ALTER TABLE Client NOCHECK CONSTRAINT ALLAlter Table Client Drop Column Foreign Key Boss_ID;I went into the Object Explorer and deleted the FK lines from eachtable, but still the same error.What am I doing wrong?Thanks for your help.
Both tblRoom and tblEquipment have the red line error which when I highlight say the they both reference an invalid table!
Both tables are there and have primary keys defined as ID & Type. I have searched around and all I could find was that there maybe a permission problem.
Let's say you have a Users table, which simply contains a collection of people. Each person has attributes like their password, first and last name, username, etc. It would be useful to track changes to that table over time, so that if an entry is changed, you can simply look at a history table and see which changes occured, and when.
An INSERT/UPDATE trigger works well for this sort of thing, where the trigger inserts all of the 'INSERTED' values into a history table that has basically the same table definition as the Users table. But it gets tricky when considering Deletes.
If my History table entries reference back to the User in the Users table, this means that if I ever want to delete the user, I need to delete all their History first. This means I can't keep records of user deletions, which is significant. The other approach is not to have a foreign key reference in the History table, so that if a user is deleted, I can still keep my History about that user. Including deletes.
I have been timid about doing it this way, since I felt it broke the idea of a well structured database. Is there a better way to approach this? Is there a standard way to set up triggered history to track changes, including deletions, from a table?
ALTER TABLE [Students] WITH CHECK ADD CONSTRAINT [FK_Students_Schools] FOREIGN KEY([SchoolId]) REFERENCES [Schools] ([SchoolId])
What kind of index would ensure best performance for INSERTs/UPDATEs, so that SQL Server can most efficiently check the FK constraints? Would it be simply:
CREATE INDEX IX_Students_SchlId ON Students (SchoolId) Or CREATE INDEX IX_Students_SchlId ON Students (SchoolId, StudentId)
In other words, what's best practice for adding an index which best supports a Foreign Key constraint?
Hello,I have 2 tables:- Customers with columns:customerID(prim_key),customerName(with customer's names)- Deliveries with columns:deliveryID(primKey),sender(ref_key to CustomerID from Customers),receiver(also ref_key to CustomerID from Customers);I need to select all data about deliveries, but instead of havingsender's ID and receiver's ID, I need to have their Names.I tried to do:SELECTdeliveries.deliveryID,Customers.customerName AS sender,Customers.customerName AS receiverFROMcustomers, deliveriesWHERECustomers.customerID=Deliveries.sender ANDCustomers.customerID=Deliveries.receiver;But this only works if sender=receiver, which is obvious ;)I'd like to know if there is any other way for obtaining those datawithin one queryThank you very much for your helpChris
I've created a new table in ASPNETDB.mdf called 'customerInfo'. Most of the fields are, for the moment, data that exists in one of the existing ASPNET tables eg Membership_UserId (primary key), Membership_Email, Users_UserName etc.; the list goes on. I have put a new column 'amountspent' - just to test that I can do what I think I can do, however the table doesn't display any data. Am I OK in thinking that I can use the aspnet data in my own tables and reference through foreign keys to them. I've made sure that the procedure that I used to put the table into a gridview on the webpage is OK as I did the same thing to the membership table and that displays all of its data. Can someone either explain the steps I need to make this happen correctly or point me in the direction of a noob type walkthrough. Thanks
Hello!I have a table A with fields id,startdate and other fields. id and startdateare in the primary key.In the table B I want to introduce a Foreign key to field id of table A.Is this possible? If yes, which kind of key I have to build in table A?Thx in advance,Fritz
To join the table but MUST follow the condition as bitActiv = TRUE: select emp.nvcEmpName, emp.nvcEmpAddress, ety. nvcEmployeeType from cst_EmpProfile emp left join cst_EmpType on emp.intEmployeeTypee = ety.intEmpType and emp.bitActiv = 1.
But, the sql statement doesnt output the my expected result. Because the data row return must be 1st and 2nd row as it bitActiv = true. So, how's I going achieve what i want. tq.
I have an problem with the order of the results after a join.
My first query works fine and the order of field Name ist correct.
Select * FROM (SELECT * FROM dtree A1 WHERE A1.Subtype=31356 AND A1.DataID IN (select DataID from dtreeancestors where AncestorID=9940974)) t
When I do a join the order of the left table changes
Select * FROM (SELECT * FROM dtree A1 WHERE A1.Subtype=31356 AND A1.DataID IN (select DataID from dtreeancestors where AncestorID=9940974)) t, llattrdata A4 WHERE t.DataID = A4.ID
How can I do a join and keep the order of the left table?
I have a query that include a single LEFT JOIN. I would like to be able to select at most 1 row of the second table (providing that the JOIN represents a one to many relationship).
Does anyone knows how to do that? Thanks in advance, Joannès
