I would like to use IBatis for polling 3 legacy databases for new rows and insert into a new database. But our customers don't allow me to insert one "status" column in three legacy databases which help me avoid consuming twice or more. So what do I have to do? Thanks in advance!
Create a new table with the status column and add a foreign key pointing to the primary key of the legacy table. Create a view with both tables joined together and you will have your status column associated with the legacy table without altering it.
You can use the idempotent consumer EIP to filter out duplicates
http://camel.apache.org/idempotent-consumer.html
But as Joachim said, you need a new table to store the status.
You can maybe also create a SQL VIEW on the original table + status table, and let iBatis query that view.
Related
I've been working with Entity framework in C# trying to figure out how to join two tables together. I found a reference here http://msdn.microsoft.com/en-us/data/jj715646.aspx on how to do this. Problem is, the two tables have PKs that are not in sync which seems to be a requirement. I've never had to worry about syncing PKs from two tables in a database before. I know I can turn off identity insert on one table but I see comments from numerous people that this is a very bad idea. If I'm not supposed to do this, then how do I accomplish syncing the PKs in each of the tables?
I have two tables in a database:
User
pkID (int)
FirstName (varchar)
LastName (varchar)
Email (varchar)
...
LockedFlags (locking fields in user from being edited)
pkID
fkUserID
bFirstName (bool)
bLastName (bool)
bEmail (bool)
I'm curious on why people thing that removing the identity insert on a table is a bad idea... if I'm relying on MSSQL to assign a PK then I could see an instance when I'm inserting a record into the database where the second table write could get a different value when dealing with multiple writes...
It sounds like you have orphaned rows in the LockedFlags table, like a row with a user ID that points to a user that has been deleted. Depending on how the relationship is setup it can also be true for the reverse.
If you have a entity where the 2 tables are combined into a single class, loading the entity set will query both tables and require matching pairs of rows.
Your LockedFlags probably has a User property which it is trying to load and cannot find in the user table.
Table options:
Note: I'm using MSSQL equivalent as I don't know MYSQL.
Comments regarding your data model:
I don't know how MYWSQL handles record locking but if it is anything like MSSQL, you do not have to worry about manually handling.
I would strongly suggest re-looking at your data model if you're going to use it as is. Just using a single table would be best if you really want to manually lock individual row fields?
Edit:
ALTER TABLE LockFlags ADD CONSTRAINT
FK_LockFlags_User FOREIGN KEY
(
UserID
) REFERENCES User
(
pkID
) ON UPDATE NO ACTION
ON DELETE NO ACTION
GO
I have four tables ie.
custAddress
custCompany
custContact and
custInfo
All of the table has 'cId' field common.
I have a interface in MVC3 view from which I will take inputs for all field except 'cId'. When I take input from the interface all of the above tables must be filled.
Also when I delete data, once I delete data from one table all the data from the other three table should be deleted.
I don't know how to use trigger for this. Please explain how can I do this using trigger or any other way. Any help is appreciated.
To me it sounds more like a database design problem. You do not need trigger here. Keep one of your table as primary (may be CustInfo) and have other table dependent(foreign key relationships) on this. Use cascade delete constraints on dependent tables. When you delete data from CustInfo, cascade delete constraint will take care of deleting corresponding data from dependent tables.
I'm actually managing and updating a Webapp which DB is on MySQL Server 5.x and all tables are InnoDB, my problem comes when I need to create a new tables with foreign key that references to an existing one, and which one has live data. When I try to execute the create command it throws the famous errno 1005, The problem is solved if I delete all info of father table , create son table and reload data on father one (this is for constraints, I think). This will be a pain if father table has a grandfather table a it contains data too.
I was wondering if there is a way to do this task easily, maybe a command that includes ignoring constraints?
From what I can see from the MySQL documentation, you could try using
SET foreign_key_checks = 0
I've come across posts of cases where that doesn't always work.
Your next best option is to make the data conform to what the FK constraint will require, then apply the constraint. That is not necessarily uncommon when adding FK constraints to tables that already have data.
I have quick question for you SQL gurus. I have existing tables without primary key column and Identity is not set. Now I am trying to modify those tables by making existing integer column as primary key and adding identity values for that column. My question is should I first copy all the records from the table to a temp table before making those changes . Do I loose all the previous records if I ran the T-SQL commnad to make primary key and add identity column on those tables. What are the approaches should I take such as
1) Create temp table to copy all the records from the table to be modified
2) Load all the records to the temptable
3) Make changes on the table schema
4) Finally load the records from the temp table to the original table.
Or
there are better ways that this? I really appreciate your help
Thanks
Tools>Options>Designers>Table and Database Designers
Uncheck "Prevent saving changes that require table re-creation"
[Edit] I've tried this with populated tables and I didn't lose data, but I don't really know much about this.
Hopefully you don't have too many records in the table. What happens if you use Management studio to change an existing field to identity is that it creates another table with the identity field set. it turns identity insert on and inserets the records from the original table, then turns identity insert off. Then it drops the old table and renames the table it just created. This can be quite a lengthy process if you have many records. If so I would script this out and then do it in a job that runs during the off hours because the table will be completely locked while you do this.
just do all of your changes in management studio, copy/paste the generated script into a file. DON'T SAVE CHANGES at this point. Look over and edit that script as necessary, it will probably do almost exactly what you are thinking (it will drop the original table and rename the temp one to the original's name), but handle all constraints and FKs as well.
If your existing integer column is unique and suitable, there should be no problem converting it to a PK.
Another alternative, if you don't want to use the existing column, you can add a new PK columns to the main table, populate it and seed it, then run update statements to update all other tables with new PK.
Whatever way you do it, make sure you do a back-up first!!
You can always add the IDENTITY column after you have finished copying your data around. You can also then reset the IDENTITY seed to the max integer + 1. That should solve your problems.
DBCC CHECKIDENT ('MyTable', RESEED, n)
Where n is the number you want the identity to start at.
I am using SQL Server 2000 and I have two databases that both replicate (transactional push subscription) to a single database. I need to know which database the records came from.
So I want to add a fixed column specified in the publication to my table so I can tell which database the row originated from.
How do I go about doing this?
I would like to avoid altering the main databases mostly due to the fact there are many tables I would need to do this to. I was hoping for some built in feature of replication that would do this for me some where. Other than that I would go with the view idea.
You could use a calculated column Use the following on the two databases:
ALTER TABLE TableName ADD
MyColumn AS 'Server1'
Then just define the single "master" database to use a VARCHAR column (or whatever you want) that you fill using the calculated columns value.
You can create a view, which adds the "constant" column, and use it as a replication source.
So the solution for me was to set up the replication publications to allow transformations and create a DTS package for each site that appends the siteid into the tables to keep the ids unique as I can't use guids.