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How to use conditional unique constraint in SQL Server?
For earlier versions of SQL Server, please see this answer. You could move the deleted records to a table that lacks the constraint, and perhaps use a view with UNION of the two tables to preserve the appearance of a single table. You can do this in a really hacky way… Create an schemabound view on your table.
What happens when you add a unique constraint to a table?
When a UNIQUE constraint is added to an existing column or columns in the table, by default, the Database Engine examines the existing data in the columns to make sure all values are unique. If a UNIQUE constraint is added to a column that has duplicated values, the Database Engine returns an error and does not add…
Can you create unique constraint for recordstatus column?
Plenty of gotchas because of that. Because, you are going to allow duplicates, a unique constraint will not work. You can create a check constraint for RecordStatus column and a stored procedure for INSERT that checks the existing active records before inserting duplicate IDs.
What’s the difference between unique index and unique constraint?
A unique index ensures that the values in the index key columns are unique. A unique constraint also guarantees that no duplicate values can be inserted into the column(s) on which the constraint is created.
Which is formula returns 5 unique values in Group A?
In the example shown, the formula in D5 is: which returns the 5 unique values in group A, as seen in E5:E9. This example uses the UNIQUE function together with the FILTER function. Working from the inside out, the FILTER function is first used to remove limit data to values associated with group A only:
How does the unique function in Excel work?
Insider filter the expression C5:C16=E4 returns an array of TRUE FALSE values like this: This array is used to filter data, and the FILTER function returns another array as a result: This array is returned directly to the UNIQUE function as the array argument.
How to find unique values in a list in Excel?
Summary To extract a list of unique values from a set of data, while applying one or more logical criteria, you can use the UNIQUE function together with the FILTER function. In the example shown, the formula in D5 is: = UNIQUE(FILTER(B5:B16, C5:C16 = E4))