For a project i need to to delete all data from all tables in a database,
I tried
DELETE FROM table1,table2,table3,...;
But it doesnt work. Any advice ? Thank
I would like to refer You to this related post
How do I use cascade delete with SQL Server?
as You will find there several possible solutions.
When using SQL it means that Your data is relations, which means most of the records are somehow related in the different tables and this relation is expressed with foreign keys. However when attempting to delete data which is id is related with data in another table a cascade deletion should be implemented, the other way around it is add additional boolean column named isDeleted(as example ofcourse) and just alter specific rows to true in this specific column and then filter by preferences. Hopefully I have managed somehow to provide with alternative and/or possible solution to Your problem.
Leaving also this link which gives some examples on cascade deletion and guide on how to implement it. ->
https://www.sqlshack.com/delete-cascade-and-update-cascade-in-sql-server-foreign-key/
P.S. also if You want just to DELETE all the data You can either use TRUNCATE TABLE or DROP DATABASE query. With the latest option You will have to recreate the database once more.
Because you want to delete all databases from all tables, you are essentially deleting the database.
The sqlite way of doing this is to just delete the database file.
In contrast to postgres or mongodb or most databases, sqlite doesn't have a server so no need to call DROP DATABASE.
As soon as the file is gone and you open the database from your application you will be in a blank state again.
Related
I've been working on deleting all the rows in Azure table in java. Can I do it without querying it?
Thanks in advance
If I retrieve all the data, can I perform delete query on that?
If you just want to delete data, you just need to retrieve PKs and RKs. After retrieved all the data of PKs and RKs, you could perform the delete query for the entities one by one.
For complex delete query, for example, below query is not supported currently.
delete from tablename where PK = ''
I suggest you submit your idea on Azure feedback site which is used for features request.
https://feedback.azure.com/forums/217298-storage
If you don't want to query the table, what you can do is to delete the table and recreate it.
I am working on some scripts that will modify many records in a table if they meet certain conditions.
In case my script is wrong, I need a quick and easy way to revert back to the original values of a table.
Currently, I am doing the following
Right click on the database
Tasks ---> Generate Scripts
Then I select Drop - Create with data or data + schema
This never works because the table I need to backup has foreign key constraints.
I just want to generate a script that wipes the values and inserts the old ones to a table. Does anyone know a simple trick for this?
I have an Access front end for a SQL database. I can add, update and delete records directly in the tables from Access. I can also update and delete rows from queries based on those tables. However, I am unable to add records to any queries. They can be simple queries based on one table with no criteria, it doesn't matter. I am unable to add rows.
I am the db owner, by the way, so permissions should not be a problem. Also, like I said, I can add directly to the tables, just not through queries.
Have any of you experienced this behavior?
Thank you for any help you can provide!
I am currently creating a database at work that is essentially a child of another database. When our clients get our software they get a database, lets call it MasterBase. This database contains schema of two different smaller databases put together, lets call them MasterC and MasterF.
My job is to take all the schema that pertain to MasterF and put them in their own database. The problem is there are a lot of references to tables and views in MasterC. To work around this I will add a property that will pair MasterF with MasterC so that in my .NET solution I should be able to do things like:
Table tableName.... (table being created in MasterF)
References .... MasterC.dbo.tableC (table in MasterC)
However, in SQL this raises the error: MSG 1763 Cross-Database foreign key references are not supported.
I have read the most common work around is to add a trigger, but seeings how this is not that safe and there are MANY instances of this I was wondering if there was another way, perhaps a stored procedure or something of the sort.
If a trigger is really the best/only way and I MUST add a trigger to every table that has this problem, how would I go about writing this trigger, I know a little SQL but am hardly proficient.
Please Help!
Triggers (as you mention)...
Database Partitioning...
Duplicate the tables from MasterC (are they transactional? How often are they updated? Does MasterC need the updates? If so, can you allow for the copies to be updated every 24-hours, etc. via a "Job"?)
Per your last comment about individual builds, I guess I'd say that the threshold for when a client "needs" both is when they...well, "need" both. Sounds almost like you need a 3rd schema, for tables in MasterC that do NOT reference MasterF, for those clients you're categorizing as not needing both.
BTW -- this is all about referential integrity, yes? There are other strategies you could employ toward that goal, besides 'relationships'.
EDIT
CREATE TRIGGER myTrigger ON myTable
AFTER INSERT
AS
IF NOT EXISTS (SELECT * FROM OtherDatabase.otherschema.othertable F
JOIN inserted AS i
ON F.KeyYouAreLookingFor = i.KeyYouHave)
BEGIN
RAISERROR ('Lookup Value Not Found -- Insert Failed', 16, 1);
ROLLBACK TRANSACTION;
RETURN
END;
One third party app is storing data in a huge database (SQL Server 2000/2005). This database has more than 80 tables. How would I come to know that how many tables are affected when application stores a new record in database? Is there something available I can retrieve the list of tables affected?
You might be able to tell by running a trace in SQL Profiler on the database - the SQL:StmtCompleted event is probably the one to monitor - i.e. if the application does a series of inserts into multiple tables, you should see them go through in Profiler.
You can use SQL Profiler to trace SQL queries. So you will see sequence of calls caused by one button click in your application.
Also use can use metadata or SQL tools to get list of triggers which could make a lot of actions on simple insert.
If you have the SQL script that used to store the new record(Usually, it should be insert statement, or other DML statement such as update, merge and so on). Then you may know how many tables were affected by parsing those SQL script.
Take this SQL for example:
Insert into emp(fname, lname)
Values('john', 'reyes')
You can get result like this:
sstinsert
emp(tetInsert)
Tables:
emp
Fields:
emp.fname
emp.lname
you can add triggers on tables that get fired on update - you could use this to update a log table that would report what was being updated.
see more here: http://www.devarticles.com/c/a/SQL-Server/Using-Triggers-In-MS-SQL-Server/
Profiler is the way to go, as others have said especially with an unfamilar third party database.
I would also spend some time creating diagrams so you can see the foreign key relationships and understand how the database is put together. I usaully know my database structure so well, I can tell from the fields being inserted what tables they affect and I know what triggers are on my tables and what they affect. There is no substitute for taking the time to understand the database you support.