SQL Server Does Not Delete Records

I am new开发者_运维知识库bie to MSSQL Server and don't have any knowledge about it.

i have below question.

I have added nine records with same value as show per below image in SQL Server 2005.

i Have not given any primary key to Table.

Now when i selecting one record or multiple record and hit the delete key it does not delete the records from table instead it gives me error.

You need to add a primary key to uniquely identify each record, otherwise the SQL server has no way of distinguishing the records, and therefore no way of knowing which one to delete, causing an error.

That's because you don't have any primary key and server doesn't know which row to remove. Clear the table ( DELETE * FROM dbo.Patient ) and create new Id column as a primary key.

In MSSQL you need to have a primary key for the table. This will uniquely identify each row of that particular table.

For example in Oracle you don't need this as there you can use ROWID (meaning every row from every table has a unique ID in the database). Once you know this ID you Oracle knows for sure from which table it is.

So now you can add a primary key to the table and you can make it be auto-increment - ensuring uniqueness.