SQLite, one of the most widely deployed database engines offers several distinctive features to developers. Here are a few sqlite interview questions that might make it easier for you to grab the job next time you apply for one.
What is SQLite?
SQLite is a relational database management system compatible with ACID. In fact, a relatively small library of the C language contains this database management system.
List the standard SQLite commands.
Standard SQLite commands that interact with relational databases are like SQL.
What are SQLite transactions?
A transaction is a unit of work that is performed against a database. ACID defines the properties of one or more changes to the database as listed below:
- Atomicity: ensures a successful completion of all the transactions.
- Consistency: ensures that the database changes state on successful transaction.
- Isolation: allows transparent working of transactions, independent of each other.
- Stability: ensures perseverance of the result or effect of a committed transaction, in the event of a system failure.
What are the areas that use SQLite?
SQLite works with
- Built-in devices and the Internet of things
- Application File Formats
- Data analysis
- Enterprise data cache
- Server-side databases
- File archives
- Internal or temporary databases
- A replacement for ad hoc files
- Experimental extensions of SQL language
- In standby mode for an enterprise database during a demonstration or testing
List the advantages of SQLite?
- To work, you do not need a separate service processor system
- SQLite comes with a zero configuration. Thus, there is no need for configuration or administration.
- One cross-platform disk can store a SQLite database
- SQLite is compact – less than 400 KiB
- SQLite is standalone, which means no external dependencies
- And, it supports almost all OS types
- Also, you need to use ANSI-C to write it, and it provides an easy-to-use API
What are storage classes in SQLite?
SQLite storage classes include
- Null: NULL
- Integer: represents an integer with a sign (1, 2, 3, etc.)
- Real: IEEE 8-byte floating-point number
- Text: a text string that is stored using the database encoding (UTF-8, UTF-16BE)
- BLOB (Binary Large Object): Accurate storage of a block of data when you enter
What command do you use to create the database in SQLite?
To create a database in SQLite, use the “sqlite3” command. For this purpose, the basic syntax for creating a database is $ sqlite3 DatabaseName.db.
What is the maximum size of VARCHAR in SQLite?
Generally, SQLite does not have a specific length for VARCHAR. For example, you can declare VARCHAR (10), and SQLite will store 500 million characters there. It will keep all 500 characters intact.
What are the cases when you need to use SQLite and when not?
SQLite can be used in the following conditions:
- Embedded applications: do not require an extension, for example, mobile apps or games
- Disk assess replacement: an application that requires direct writing or reading files to disk
- Testing: when testing the logic of business applications
On the other hand, you need not to use SQLite for:
- Multi-user applications: In cases, where multiple clients must have access and use the same database
- Applications that require large volume records: It allows you to use only one write operation at a time
How to recover deleted data from a SQLite database?
To restore information, you can use a backup of the database file. In case, you didn’t create a backup earlier, recovery is impossible. SQLite uses SQLite SECURE DELETE, which overwrites all deleted content with zeros.
In which case can I get an error SQLITE_SCHEMA?
SQLITE_SCHEMA error occurs if the prepared SQL statement is invalid and its execution fails. This error occurs only when using the sqlite3 prepare () and sqlite3 step () interfaces to run SQL.
What is EECN in SQLite?
Any ECCN does not describe the source code of the main source of the public domain SQLite. Therefore, specify ECCN as EAR99. But, if you add a new code or associate SQLite with the application, it can change the EECN number.
What are SQLite indexes?
SQLite indexes are special lookup tables used by the database search engine to speed up the discovery of data. In simple words, this is a pointer to the data in the table.
When should I avoid indexes?
Basically, avoid indices if
- Tables small
- Tables change frequently
- Often used columns or those with many NULL values
To conclude, having knowledge of these sqlite interview questions and answers improves your chances of getting a job.
Was this article useful for you? Feel free to share your queries, feedback, comments, and concerns about these sqlite interview questions in the below comment section.