From a purely querying standpoint, it makes no difference whether your key is descending or ascending if you want to pull N most recent or N oldest records: The internal algorithms of SQL Server can navigate equally efficiently in both directions on a single-column index, regardless of the sequence in which the keys are stored. … Read more
I wouldn’t call it an issue. This is default behaviour for many database systems. Basically, the auto-increment counter for a table is persistent, and deleting entries does not affect the counter. The actual value of the primary key does not affect performance or anything, it only has aesthetic value (if you ever reach the 2 … Read more
If you use management studio, simply select the wardNo, BHTNo, testID columns and click on the key mark in the toolbar. Command for this is, ALTER TABLE dbo.testRequest ADD CONSTRAINT PK_TestRequest PRIMARY KEY (wardNo, BHTNo, TestID)
When dealing with UUID numbers store them as data type uuid. Always. There is simply no good reason to even consider text as alternative. Input and output is done via text representation by default anyway. The cast is very cheap. The data type text requires more space in RAM and on disk, is slower to … Read more
drop constraint and recreate it alter table Persion drop CONSTRAINT <constraint_name> alter table Persion add primary key (persionId,Pname,PMID) edit: you can find the constraint name by using the query below: select OBJECT_NAME(OBJECT_ID) AS NameofConstraint FROM sys.objects where OBJECT_NAME(parent_object_id)=’Persion’ and type_desc LIKE ‘%CONSTRAINT’
Is it a bad idea to use a UUID (String / Varchar) as primary key in a android sqlite database table instead of an integer that would be auto incremented? The only for-certain problem that I can think of is that you will not be able to use CursorAdapter and its subclasses for displaying the … Read more
You cannot create a primary key on a view. In SQL Server you can create an index on a view but that is different to creating a primary key. If you give us more information as to why you want a key on your view, perhaps we can help with that.
When you perform an insert in a row the DB, it will be inserted in order relative to the other PKs in the table. With a normal guid, this could be anywhere in the table. A newsequentialid() will always be added to the end of the table. So the performance of inserts is improved. This … Read more
I would use composite key, and no extra meaningless key. I would not use a ORM system that enforces such rules on my db structure.
Django now has a BigAutoField built in if you are using Django 1.10: https://docs.djangoproject.com/en/1.10/ref/models/fields/#bigautofield