Function-based indexes in SQL Server
I'm trying to understand if function based indexes similar to the one's in Oracle or PostgreSQL exist in SQL Server
In PostgreSQL, I can create a function based index using by using the following syntax:
CREATE INDEX sample ON "TestDB" (("expression1" || ' ' || "expression2"));
I found a article where I found something called "index on computed columns" in SQL Server. Is this a function based index just like in Oracle/PostgreSQL? Can anybody provide me a sample query to create/view such an index?
I researched a bit further based on Damien's comment and found an answer that comes very close to matching Oracle's/PostgreSQL's function based indexes.
I have a table named PARCELS where I created a new column COMPUTEDPARCELS by using the alter statement as given below:
ALTER TABLE [PARCELS] ADD COMPUTEDPARCELS AS CONVERT(CHAR(8), [MAPNO], 112);
And then create an index on the computed column:
CREATE INDEX function_index ON [PARCELS](COMPUTEDPARCELS);
Of course the example is pretty simple but behaves just like a function based index.