Bugl — code interview practice that feels like a game

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Flash cards

Review the key moves

1/4

Core idea

What is the main idea behind SQL CREATE UNIQUE INDEX Keyword?

Lesson checks

Practice each idea before moving on

Short Mimo-style checks built from this lesson's code, terms, and sequence.

1Quick choice

Which statement best captures the main point of this lesson?

2Fill blank

Complete the missing token from the example code.

___ UNIQUE INDEX uidx_pid

3Order

Put the learning moves in the order that makes the concept easiest to apply.

Indexes are used to retrieve data from the database very fast.

The CREATE UNIQUE INDEX command creates a unique index on a table (no duplicate values allowed)

Create Unique Index

The CREATE UNIQUE INDEX command creates a unique index on a table (no duplicate values allowed)

Indexes are used to retrieve data from the database very fast. The users cannot see the indexes, they are just used to speed up searches/queries.

The following SQL creates an index named "uidx_pid" on the "PersonID" column in the "Persons" table:

CREATE UNIQUE INDEX uidx_pid
ON Persons (PersonID);

Note

The syntax for creating indexes varies among different databases. Therefore: Check the syntax for creating indexes in your database.

Note

Updating a table with indexes takes more time than updating a table without (because the indexes also need an update). So, only create indexes on columns that will be frequently searched against.