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SQLite Interview Questions and Answers

By Umesh Singh
Last update: 30 Nov 2019, 22 Questions
SQLite Interview Questions

Most Frequently Asked SQLite Interview Questions

1. Who developed SQLite and when?

SQLite was developed by Dwayne Richard Hipp in the year 2000

2. Why was SQLite designed?

SQLite was primarily designed for the purpose that while operating a program, there will not be a requirement of administration or set-up.

3. What are the features of SQLite?
  • The code for the SQLite is in the public domain therefore SQLite is free to use
  • SQLite does not require the server to operate
  • SQLite allows the user to work on multiple databases at the same time
  • There is no need to install "SQLite" before using it.
  • SQLite has the capability of creating the in-memory database, and the user can work very fast with it.
4. Explain the difference between SQL and SQLite?
S.no SQL SQLite
1. SQL is server based SQLite is file base
2. SQL is a query language SQLite is an embedded database management system
3. SQL supports the stored procedure SQLite does not support the stored procedure

This particular SQLite Question and Answer defines explicitly the difference between SQL and SQLite.

5. What are the standard commands in SQLite?

The standard commands in SQLite are:-

  • SELECT
  • CREATE
  • INSERT
  • UPDATE
  • DROP
  • DELETE
6. List down the area where SQLite performs well.

Here are some of the areas:-

  • Embedded devices
  • Websites
  • File archives
  • Testing
  • Data Analysis
7. What are the storage classes in SQLite?

SQLite storage classes include the following:

  • Null: It has a NULL value.
  • Integer: The value is a signed integer (5,6,7, etc.)
  • Real: The numbers with a decimal point (1.2,3.4 etc.).The real numbers are stored as an 8 byte IEEE floating point number.
  • Text: It holds a text string.
  • BLOB: The value is a blob of data, and it is stored exactly as it was input.
8. What are the operators in SQLite?

There are four operators in SQLite:-

  • Arithmetic operators(+,-,*,/,%)
  • Comparison operators(==,=,!=,<>,<,>,>=,<=,!<,!>
  • Logical operators(AND, BETWEEN, EXISTS, IN, NOT IN, LIKE, GLOB, NOT, OR, IS NULL, IS, IS NOT, ||, UNIQUE)
  • Bitwise operators(&, I,~,<<,>>)

Point to be noted: Make sure that you go through this Q&A twice as this is the favorite SQLite Questions and Answers for fresher and experienced as well.

9. Explain how Boolean values are stored in SQLite?

SQLite incorporates Boolean as an integer variable rather than having a separate Boolean class. Boolean values are stored in SQLite as integers 0 which means false and 1 which means true.

10. How to create a database in SQLite?

The command “sqlite3” is used to create a database.

Syntax:-$sqlite3 DatabaseName.db

11. What is the role of the Index in SQLite?

Indexes are the lookup tables which are used by the database Engines to speed up the process of retrieving of the data. We can say that the Index is a pointer to the data in a table.

12. What are the SQLite transactions?

In SQLite, the transaction is mentioned as a unit of work performed against a database. The properties of a transaction are determined by four factors also called ACID.

  • Atomicity: Ensures work of units to be completed successfully.
  • Consistency: Ensures the states of database change after every successful transaction.
  • Isolation: This enables SQLite transactions to operate independently and transparent to each other.
  • Durability: This ensures the effect of committed transactions stays in case of system failure.

This question has always been a center of the discussion in SQLite Interview Question Android

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13. How to delete or add columns from an existing SQLite table?

The user has first to save the existing data to a temporary table. Then, then drop the old column or table, create a new table and copy the data back that put in the temporary table. The support for the altar table is minimal.

14. What is the maximum size of an SQLite VARCHAR?

There is no specific length for VARCHAR in SQLite. Users can declare a VARCHAR(10), and SQLite is capable of storing a 500 million character string there while keeping all the characters intact.

15. When to and when not to use SQLite?

SQLite is a pretty advanced and useful database management system, but as like many there are areas where it standout and regions where it is vulnerable. It can be helpful in conditions like embedded applications, testing and disk assess replacement, whereas it is not advised to use SQLite for multi-user applications and applications requiring high write volumes.

16. When does SQLITE_SCHEMA error appear?

This error appears when a prepared SQL statement is not valid and can’t be executed. This error usually occurs when we use the sqlite3 step() and sqlite3 prepare() interfaces to run SQL.

17. How do we use a string literal which contains an embedded single-quote (‘) character?

The standard SQL specifies that single-quotes in strings can be escaped by putting two single in a row. In this scenario, it works with the Pascal programming language.

18. What do you mean by the Export Control Classification Number (EECN) in SQLite?

The source code for the core public domain SQLite is not described by any EECN. That’s why the ECCN should be reported here as EAR99. But, we add new code or link SQLite with an application, then it may change the EECN number.

19. How to create an AUTOINCREMENT field in SQLite?

The user has to declare an INTEGER PRIMARY KEY column on the table at first. After this, whenever we insert a NULL into that column of the table, it will automatically be converted into an integer which is one greater than the most considerable value of that column over all the other rows present in the table.

20. What are the methods to insert data in the SQLite table?

There are two ways to insert data in an SQLite table:

1. INSERT INTO TABLE_NAME [(column1, column2, column3,...columnN)] VALUES (value1, value2, value3,...valueN);

2. INSERT INTO TABLE_NAME VALUES (value1,value2,value3,...valueN);

21. What is UPDATE query in SQLite?

In SQLite, we use the UPDATE query to modify the existing records in an SQLite table. The user has to use the WHERE clause for specific row modification otherwise all rows will be updated to the same.

22. How can we delete the existing records for an SQLite table?

The DELETE can be used in SQLite to delete the existing records from a table. We should use the WHERE clause to modify a specific row otherwise all rows will be removed.

Example

                                                    

DELETE FROM table_name