Create Index:

CREATE NONCLUSTERED INDEX ix_IndexName ON dbo.TableName (Column1 ASC);

We can leave out some of the default values:

CREATE INDEX ix_IndexName ON dbo.TableName (Column1);

Create index with a unique constraint:

CREATE UNIQUE NONCLUSTERED INDEX ix_IndexName ON dbo.TableName (Column1);

Index with Included columns:

CREATE INDEX ix_IndexName ON dbo.TableName (Column1)
    INCLUDE (Column2, Column3);

Disable and Re-enable Index:

Occasionally you may want to run a query without using an index, to compare how it runs without it. Or you may not want the indexes when you’re loading a lot of data. Instead of dropping the index, you can disable it, then re-enable with a REBUILD.

ALTER INDEX ix_IndexName ON dbo.TableName DISABLE;

ALTER INDEX ix_IndexName ON dbo.TableName REBUILD;

You can use these commands to disable all indexes on a table.

ALTER INDEX ALL ON dbo.TableName DISABLE;

ALTER INDEX ALL ON dbo.TableName REBUILD;

Drop Index:

SQL Server 2016 and later uses IF EXISTS, so it won’t try to drop an index if it does not exist.

DROP INDEX IF EXISTS ix_IndexName ON dbo.TableName;

Links:

Microsoft – Create Index

Microsoft – Drop Index

Database.Guide – How to disable an index in SQL Server