I created a SQL-Lite Database with a few tables in it.
TBL User:
UsrName PK
TBL Car
CarID PK
NotRentable BOOL
TBL CarUser
UsrName PK, FK CHECK(WHERE Car.CarID = CarID AND NotRentable = FALSE)
CarID PK, FK
Now I came across the possibility to have custom constraints on the to be created database entry using the "CHECK" keyword in different SQL dialects.
The examples the internet provides are more simple in the way that only the table that the entry should be written to can be queried using the CHECK keyword.
Is it possible to execute more complex sql-queries which evaluate as True or False as constraints before adding the new data to the table? This is a huge error source, but my intention would be to only use it for very basic matters. Like in the sample above! Thanks for your suggestions.
Related
I have a table that has a primary key WORKITEMID, and the following 3 foreign keys PRODSERVID,PROCESSID,and TASKKNOWID.
I have a view that I can create that also has PRODSERVID,PROCESSID, AND TASKKNOWID. This view will usually have ALL the records in above table plus some new ones - not in the table. The 'table' by definition is meant to hold the unique combinations of PRODSERVID, PROCESSID, and TASKKNOWID.
I would like to insert from the view into the table any new combinations in the view not present in the table. And I don't want to overwrite the existing WORKITEMIDs in the INSERT- because those WORKITEMIDs are used elsewhere.
Can this be done in SQL?
Thanks
Absolutely, the simplest form of criteria for this is to use the negation of EXISTS()
INSERT INTO [TableName] (PRODSERVID,PROCESSID,TASKKNOWID,... )
SELECT PRODSERVID,PROCESSID,TASKKNOWID,...
FROM [ViewName] v
WHERE NOT EXISTS (
SELECT 1 FROM [TableName] t
WHERE t.PRODSERVID = v.PRODSERVID AND t.PROCESSID = v.PROCESSID AND t.TASKKNOWID = v.TASKKNOWID
)
replace the ... with your other fields
You could also use a non-corellating outer join but I find not exists makes the intent much clearer.
There is a good comparison of the different approaches to this issue in this article: T-SQL commands performance comparison – NOT IN vs SQL NOT EXISTS vs SQL LEFT JOIN vs SQL EXCEPT
I am not able to get generated key from column organized table from an INSERT SQL statement run against IBM DB2 warehouse. I am using Java and JDBC driver. Everything works fine - I am able to connect to DB, create tables, insert data, I am just not able to get a generated key if it is generated in column organized table. Note that row organized tables work fine and return the key properly.
Consider a table:
CREATE TABLE users (
id INTEGER not null GENERATED ALWAYS AS IDENTITY (START WITH 1 INCREMENT BY 1),
username VARCHAR(16),
PRIMARY KEY (id)
);
If this is row organized table I am able to get the generated key fine by using:
PreparedStatement pr = connection.prepareStatement("INSERT INTO users(username) VALUES(?)", PreparedStatement.RETURN_GENERATED_KEYS);
However, If this is column organized table the PreparedStatemnt creation fails with an error:
com.ibm.db2.jcc.am.SqlSyntaxErrorException: DB2 SQL Error: SQLCODE=-1667, SQLSTATE=42858, SQLERRMC=BLUADMIN.USERS;ORGANIZE BY COLUMN;FINAL|NEW|OLD TABLE, DRIVER=4.25.13
Even if I specify columns I want to get returned like so:
PreparedStatement pr = connection.prepareStatement("INSERT INTO users(username) VALUES(?)", new String[]{"id","username"});
pr.setString(1, "test");
pr.executeUpdate();
I get
com.ibm.db2.jcc.am.SqlSyntaxErrorException: DB2 SQL Error: SQLCODE=-1667, SQLSTATE=42858, SQLERRMC=BLUADMIN.USERS;ORGANIZE BY COLUMN;FINAL|NEW|OLD TABLE, DRIVER=4.25.13
on line pr.executeUpdate();.
Does this mean that it is not possible to get generated key from column organized table from the INSERT statement in DB2 Warehouse?
Currently shipping versions v11.1.x and V11.5.x will throw SQL1667N when the query sent to Db2 uses 'FINAL TABLE' or 'OLD TABLE', or 'NEW TABLE' clauses for a column organized table.
When you use the jdbc syntax PreparedStatement.RETURN_GENERATED_KEYS, this syntax may be used under the covers.
Currently those clauses are not supported (i.e. will cause the exception to be thrown) for ORGANIZE BY COLUMN tables. There are other restrictions on column organized tables that you should be aware of before using them.
You can workaround this by creating your tables explicitly with the ORGANIZE BY ROW clause.
Have you tried actually selecting the generated ID? Try something like this:
SELECT ID FROM FINAL TABLE
(INSERT INTO users(username) VALUES(?))
See "Retrieval of result sets from an SQL data change statement" in the IBM Db2 documentation.
I want to add another row in my existing table and I'm a bit hesitant if I'm doing the right thing because it might skew the database. I have my script below and would like to hear your thoughts about it.
I want to add another row for 'Jane' in the table, which will be 'SKATING" in the ACT column.
Table: [Emp_table].[ACT].[LIST_EMP]
My script is:
INSERT INTO [Emp_table].[ACT].[LIST_EMP]
([ENTITY],[TYPE],[EMP_COD],[DATE],[LINE_NO],[ACT],[NAME])
VALUES
('REG','EMP','45233','2016-06-20 00:00:00:00','2','SKATING','JANE')
Will this do the trick?
Your statement looks ok. If the database has a problem with it (for example, due to a foreign key constraint violation), it will reject the statement.
If any of the fields in your table are numeric (and not varchar or char), just remove the quotes around the corresponding field. For example, if emp_cod and line_no are int, insert the following values instead:
('REG','EMP',45233,'2016-06-20 00:00:00:00',2,'SKATING','JANE')
Inserting records into a database has always been the most common reason why I've lost a lot of my hairs on my head!
SQL is great when it comes to SELECT or even UPDATEs but when it comes to INSERTs it's like someone from another planet came into the SQL standards commitee and managed to get their way of doing it implemented into the final SQL standard!
If your table does not have an automatic primary key that automatically gets generated on every insert, then you have to code it yourself to manage avoiding duplicates.
Start by writing a normal SELECT to see if the record(s) you're going to add don't already exist. But as Robert implied, your table may not have a primary key because it looks like a LOG table to me. So insert away!
If it does require to have a unique record everytime, then I strongly suggest you create a primary key for the table, either an auto generated one or a combination of your existing columns.
Assuming the first five combined columns make a unique key, this select will determine if your data you're inserting does not already exist...
SELECT COUNT(*) AS FoundRec FROM [Emp_table].[ACT].[LIST_EMP]
WHERE [ENTITY] = wsEntity AND [TYPE] = wsType AND [EMP_COD] = wsEmpCod AND [DATE] = wsDate AND [LINE_NO] = wsLineno
The wsXXX declarations, you will have to replace them with direct values or have them DECLAREd earlier in your script.
If you ran this alone and recieved a value of 1 or more, then the data exists already in your table, at least those 5 first columns. A true duplicate test will require you to test EVERY column in your table, but it should give you an idea.
In the INSERT, to do it all as one statement, you can do this ...
INSERT INTO [Emp_table].[ACT].[LIST_EMP]
([ENTITY],[TYPE],[EMP_COD],[DATE],[LINE_NO],[ACT],[NAME])
VALUES
('REG','EMP','45233','2016-06-20 00:00:00:00','2','SKATING','JANE')
WHERE (SELECT COUNT(*) AS FoundRec FROM [Emp_table].[ACT].[LIST_EMP]
WHERE [ENTITY] = wsEntity AND [TYPE] = wsType AND
[EMP_COD] = wsEmpCod AND [DATE] = wsDate AND
[LINE_NO] = wsLineno) = 0
Just replace the wsXXX variables with the values you want to insert.
I hope that made sense.
This question already has answers here:
How to better duplicate a set of data in SQL Server
(3 answers)
Closed 6 years ago.
I have a few tables that contain ID's that are of type GUID, pretty much every table is using GUID's instead of incremented IDs, but thats neither here nor their, just a scope of what I am dealing with.
So I have a table called
MaterialType and MaterialSubType
the MaterialType is built as the following
MaterialTypeID (PK, Uniqueidentifier, not null)
MaterialType (varchar(40), not null)
Code (varchar(100), not null)
EnabledInd (tinyint, not null)
The MaterialSubType is built as follows
MaterialSubTypeID (PK, Uniqueidentifier, not null)
MaterialTypeID (PK, Uniqueidentifier, not null)
MaterialSubType (varchar(40), not null)
Code (varchar(100), not null)
EnabledInd (tinyint, not null)
The problem I am running into is that I have two updated tables that are pretty much identical, other than the fact is that I am using autoincremented ID's, I need to figure out how to query the data from the original tables and insert the data into the new tables.
I know I can do an "insert into select" to the tables, but that doesn't (at least to my knowledge) help me because I need to have a foreign key in the MaterialSubType to the MaterialType.
So I am not sure how this should be done or how to do it, reason being is that I am not an expert with SQL or a DBA.
Again I'm making assumptions:
The code is the universal identifier that you're using to identify new records in both tables
The autoincrement identity values are on
MaterialType.MaterialTypeID and MaterialSubType.MaterialSubTypeID
(though it doesn't really make sense if you have a PK on two columns
when only one would be required in this case)
The databases are on the same SQL Server
First add new records to MaterialType so we can generate a key:
INSERT INTO TargetDB..MaterialType (MaterialType, Code, EnabledInd)
SELECT MaterialType, Code, EnabledInd
FROM SourceDB..MaterialType SRC
WHERE NOT EXISTS (
SELECT * FROM TGT
WHERE TGT.Code = SRC.Code
)
Now add new records to MaterialSubType. To get the target FK value we need to first look up the code value in the source, then use that to lookup the correct FK value in the target.
I strongly suggest you first just run the select without the insert and test some records manually.
INSERT INTO TargetDB..MaterialSubType (
MaterialTypeID,
MaterialSubType,
Code,
EnabledInd
)
SELECT
-- We get this FK value by first looking up the code in the source
-- then using that to look up the FK in the target
MT.MaterialTypeID,
SRC.MaterialSubType,
SRC.Code,
SRC.EnabledInd
FROM
SourceDB..MaterialSubType SRC
INNER JOIN
-- Join to source lookup to find the code
SourceDB..MaterialType FK
ON SRC.MaterialTypeID = FK.MaterialTypeID
-- Now we have the source code, look up the target to get the target FK
INNER JOIN
TargetDB..MaterialType MT
ON FK.Code = MT.Code
WHERE NOT EXISTS (
SELECT *
FROM TargetDB..MaterialSubType TGT
SRC.Code = TGT.Code
)
There might be some errors here. If there are, and you would like them fixed please also confirm my assumptions.
I'm trying to use set up a database for a school project, and I'm using triggers to set up referential integrity for one table. I have a table, Addresses, which stores the address for People, Studios, and Directors. Then I have a table called Address Reference. This table points to the Address table, and it has a two fields, the ReferenceID and the TableName to show which table and row this address is for. I have a Constraint so TableName will always be valid.
I'm trying to set up a trigger to make sure any rows inserted are valid, which I can do, I'm just trying to improve it. My code would look like this:
SELECT *
FROM inserted
WHERE ReferenceID IN
(SELECT PersonID
FROM inserted.TableName)
However I found I needed to use dynamic sql. So I was thinking something like this:
SELECT *
FROM inserted
WHERE ReferenceID IN
(EXEC('SELECT PersonID FROM' + inserted.TableName))
Which didn't work, even when I removed the exec.
I'm doing this in SQL Server Management Studio With SQL Server 11.0.3128
Let me know if you need any more information. I've looked around, and I haven't found any answers to this question that work.
This is a poor way to maintain referential integrity. There are a number of ways you could approach this.
The first would be to have an address table, then multiple tables to contain the links, e.g.
CREATE TABLE StudioAddress
( StudioID INT NOT NULL,
AddressID INT NOT NULL,
CONSTRAINT PK_StudioAddress__StudioID_AddressID PRIMARY KEY (StudioID, AddressID),
CONSTRAINT FK_StudioAddress__StudioID FOREIGN KEY (StudioID) REFERENCES Studio (StudioID),
CONSTRAINT FK_StudioAddress__AddressID FOREIGN KEY (AddressID) REFERENCES Address (AddressID)
);
This maintains your referenctial integrity without needing triggers, and still caters for a 1 to many relationship.
Another option would be to have 3 nullable columns in your address table (StudioID, PersonID, DirectorID), each with a foreign key to the relevant table, you can the add a check constraint to ensure only one of the 3 fields is populated (if this is required).
I much prefer the first option though, it is much cleaner, and also allows for the same address to be used for multiple things.
ADENDUM
If this has to be done using triggers, then I think you would need to use something like this:
IF EXISTS( SELECT 1
FROM inserted i
WHERE NOT EXISTS
( SELECT 1
FROM People p
WHERE p.PersonID = i.ReferenceID
AND i.TableName = 'People'
UNION ALL
SELECT 1
FROM Studios s
WHERE s.StudioID = i.ReferenceID
AND i.TableName = 'Studios'
UNION ALL
SELECT 1
FROM Directors d
WHERE d.DirectorID = i.ReferenceID
AND i.TableName = 'Directors'
)
)
BEGIN
ROLLBACK TRANSACTION;
RAISERROR('Referential integrity error', 16, 1);
END
This essentially checks that for all inserted/updated rows a record exists with the relevant ID in the relevant table.
I still stand by my earlier answer though, that this is a terrible approach, and I would question any syllabus this is on!