Day 63 – SQL CREATE INDEX Keyword
SQL CREATE INDEX keyword is used to create a new index on one or more columns of a table. An index is a data structure that improves the performance of SQL queries by allowing the database to quickly retrieve data based on the values in the indexed columns.
The basic syntax for using the CREATE INDEX keyword is as follows:
CREATE INDEX index_name
ON table_name (column1, column2, ...);
index_name is the name of the new index, and
table_name is the name of the table on which the index will be created. The
column2, etc. are the names of the columns that will be included in the index.
For example, to create an index named “idx_students” on the “Students” table, based on the “StudentID” column, the SQL statement would be:
CREATE INDEX idx_students
ON Students (StudentID);
This would create a new index named “idx_students” on the “Students” table, based on the “StudentID” column.
Indexes can improve the performance of SQL queries by allowing the database to quickly retrieve data based on the values in the indexed columns, rather than having to scan the entire table. However, indexes can also have a negative impact on performance if they are not used effectively, so it is important to carefully consider which columns to index and how to structure the indexes to best support the queries that will be run against the table.