Room queries (Insert, Update, Delete, Select) in Android Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the @Insert annotation in Room?

The @Insert annotation tells Room to generate code that inserts an entity into the database. It simplifies adding new rows without writing SQL manually.

beginner

How do you update an existing record in Room?

Use the @Update annotation on a DAO method. Pass the entity with updated fields, and Room will update the matching row based on the primary key.

beginner

What does the @Delete annotation do in Room?

The @Delete annotation marks a method to remove a specific entity from the database. Room deletes the row matching the entity's primary key.

beginner

How do you write a query to select all rows from a table in Room?

Use the @Query annotation with SQL like "SELECT * FROM tableName". The method returns a list of entities representing all rows.

intermediate

Why is it better to use Room annotations instead of raw SQL for insert, update, and delete?

Room annotations reduce errors by generating code automatically. They ensure type safety, simplify code, and integrate well with Kotlin and LiveData.

Which annotation is used to add a new entity to the Room database?

A @Delete

B @Update

C @Insert

D @Query

The @Insert annotation is specifically for inserting new rows into the database.

What does the @Update annotation require to identify which row to update?

A Column name

B Row number

C Table name

D Primary key in the entity

Room uses the primary key in the entity to find the exact row to update.

How do you delete a record using Room?

A Use @Delete with the entity to remove

B Use @Insert with null values

C Use @Update with empty fields

D Use @Query with SELECT statement

The @Delete annotation removes the entity matching the primary key from the database.

Which SQL statement is used inside @Query to get all rows from a table named 'users'?

A SELECT * FROM users

B DELETE FROM users

C UPDATE users SET

D INSERT INTO users

SELECT * FROM users returns all rows from the 'users' table.

What type of value does a @Query method that selects multiple rows usually return?

A Single entity

B List of entities

C Boolean

D Integer

Selecting multiple rows returns a List of entity objects.

Explain how to insert, update, delete, and select data using Room annotations in Kotlin.

Think about the annotations and their roles in managing database rows.

Describe why Room's annotations help avoid errors compared to writing raw SQL for database operations.

Consider how Room makes database work easier and safer.