How to create clustered index ?

To create a clustered index in a database, you can follow these steps:

1. Identify the table on which you want to create the clustered index.

2. Determine the column or columns on which you want to create the clustered index. It is recommended to choose a column that is frequently used in queries and has a unique or nearly unique value for each row.

3. Write a SQL query to create the clustered index. The syntax for creating a clustered index in SQL Server is as follows:

```sql
CREATE CLUSTERED INDEX index_name
ON table_name (column_name);
```

Replace `index_name` with the name you want to give to the clustered index, `table_name` with the name of the table on which you want to create the index, and `column_name` with the name of the column on which you want to create the index.

4. Execute the SQL query to create the clustered index. Once the index is created, the database will automatically reorder the rows in the table based on the values in the indexed column, physically storing the rows in the order of the index.

It is important to note that a table can have only one clustered index, as the data in the table is physically stored in the order of the clustered index. Additionally, creating a clustered index can have a significant impact on the performance of queries, as it can speed up data retrieval for queries that use the indexed column.