In this blog, I’m explaining about Indexes in SQL
Indexes are created on columns in tables or views. The index provides a fast way to look up data base on the values within those columns.
Types of indexes
- Clustered Indexes
- Non Clustered Indexes
Only 1 clustered index allowed per table physically rearranges the data in the table to confirm to the index constraints for use on columns that are frequently searched for ranges of data for use on columns with low selectivity.
Create TABLE [dbo].[EmployeeDetail] ADD CONSTRAINT [PK_EmployeeDetail] PRIMARY KEY CLUSTERED
Non Clustered Indexes
A non clustered Index is useful for columns that have some repeated values. A table can have more than one Non-clustered index. Non clustered column always depends on the clustered column on the database.
CREATE UNIQUE NONCLUSTERED INDEX [IX_EmployeeDetail] ON [dbo].[EmployeeDetail] (
select * from EmployeeDetail with(index(IX_EmployeeDetail_1))