What are the reasons for SQLite to be developed in C language?

I. Introduction

1.1. What is SQLite?

SQLite is an open source relational database management system, which is famous for its lightweight, embedded, zero configuration, portability and high performance. SQLite does not require a separate server process or system, it can directly use local files for data storage and access, and supports multiple operating systems and programming languages. SQLite is often used as a database solution in small applications or embedded systems.

Official download address:
SQLite Download Page

1.2, the history and current situation of SQLite

SQLite is a lightweight relational database management system (RDBMS), which has many advantages, such as easy to use, embeddable, cross-platform, etc. Originally developed by D. Richard Hipp in 2000, SQLite was originally designed to solve the need for a built-in data storage engine for a tool called AT&T's classic awk.
Since its release, SQLite has become one of the databases of choice for many applications. It is widely used in local storage, mobile device development, desktop applications and web applications. SQLite currently supports most of the syntax of the ANSI SQL standard, and can be accessed through languages ​​such as C/C++, Java, and Python.
In addition to its widespread use in applications, SQLite is increasingly becoming an alternative to other RDBMSs. SQLite is lightweight, embeddable, and easy to maintain. Compared with traditional relational databases, SQLite is more suitable for small projects and embedded applications.
The current state of SQLite is very good. It remains an active open source project with several releases each year improving its performance and functionality. The latest version of SQLite adds new features such as full-text search, JSON support, foreign key constraints, etc., which makes SQLite a more complete RDBMS. At the same time, SQLite is constantly expanding its usage scenarios, such as increasing support for multi-threaded access, providing WAL mode, and so on.

Two, the advantages of SQLite

1. Lightweight: SQLite is a small database management system that is small enough to be easily integrated into any application.
2. Simple and easy to use: SQLite does not require cumbersome server configuration and management, nor does it require a complicated installation process. It only needs to use some simple SQL commands to operate.
3. Full platform support: SQLite supports most popular operating systems, including Windows, Mac OS X, iOS, Android, etc.
4. No network connection required: SQLite is a local database management system that does not require a network connection or server and can be used offline.
5. High security: SQLite supports data encryption to ensure data security.
6. Excellent performance: SQLite is a high-performance database management system with fast read and write speeds, suitable for small-scale data storage and processing.
7. Strong portability: SQLite data files can span multiple platforms and operating systems, which is very convenient for backup and recovery.

To sum it up: fast, lightweight, no installation, easy to use, cross-platform support.

3. Reasons for using C language to develop SQLite

3.1. Advantages of C language

C language has the advantages of high performance, cross-platform support, and wide application.

1. Versatility: C language can be used to write various types of applications, including operating systems, embedded systems, games, desktop applications, network applications, etc.
2. High performance: C language is a low-level language that can directly access computer hardware resources and operating system APIs. Therefore, the execution speed of C language is very fast.
3. Strong portability: Since C language is a highly versatile language, it can be compiled and run on different platforms, so it has good portability. It can be supported across platforms.
4. High flexibility: C language provides many powerful control structures and data types, which can easily implement complex algorithms and data structures.
5. Active open source community: The open source community of C language is very active, and there are many excellent open source projects, libraries and tools, which can be used and learned conveniently.
   

3.2. Compared with other programming languages

(1) Compared with python:

1. Higher performance: C language is a low-level language that runs directly on computer hardware, so the execution speed is faster, and it can handle larger amounts of data and more complex calculations.
2. Smaller memory footprint: The SQLite library developed in C language is lighter and takes up less memory resources than the version implemented in Python.
3. Better cross-platform compatibility: Since C language is a compiled language, the developed program can be compiled on multiple platforms, while Python needs to install an interpreter to run, which makes SQLite developed in C language have better cross-platform compatibility. Platform compatibility.
4. More concise code: C language is a relatively low-level language, and its code is more streamlined, more readable, and easier to maintain and debug.
5. Better scalability: As a system-level language, C language can be more easily integrated with other languages, such as extending applications by calling DLL dynamic link libraries, SO shared libraries, etc. Python, on the other hand, needs to be implemented through C extension modules or cython.
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(2) Compared with Java:

1. Higher execution speed: C language is a low-level language that runs directly on computer hardware. Compared with the Java Virtual Machine (JVM) interpretation and execution method, the execution speed of C language is faster, especially for large amounts of data and complex calculations. Wait for the scene.
2. Smaller memory footprint: The SQLite library developed in C language is lighter than the version implemented in Java, occupies less memory resources, and can run in a resource-constrained environment.
3. Better cross-platform compatibility: Since C language is a compiled language, the developed program can be compiled on multiple platforms, while Java needs JVM to execute, so SQLite developed in C language has better cross-platform compatibility sex.
4. Better system-level programming ability: C language is a system-level language that can interact with the operating system more conveniently and realize lower-level programming functions, such as file operations and network communications. It is suitable for those who need a high degree of control over applications and systems. need.
5. More concise code: C language is a relatively low-level language, and its code is more streamlined, more readable, and easier to maintain and debug. Java's syntax and object-oriented features are more complex, requiring more code and understanding costs.
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(3) Compared with C#:

1. Higher execution speed: C language is a low-level language that runs directly on computer hardware. Compared with the C# virtual machine (CLR) interpretation and execution method, the execution speed of C language is faster, especially for large amounts of data and complex calculations. Wait for the scene.
2. Smaller memory footprint: The SQLite library developed in C language is lighter than the version implemented in C#, occupies less memory resources, and can run in a resource-constrained environment.
3. Better cross-platform compatibility: Since C language is a compiled language, the developed program can be compiled on multiple platforms, while C# requires CLR to execute, so SQLite developed in C language has better cross-platform compatibility sex.
4. Better system-level programming ability: C language is a system-level language that can interact with the operating system more conveniently and realize lower-level programming functions, such as file operations and network communications. It is suitable for those who need a high degree of control over applications and systems. need.
5. Wider application fields: C language is widely used in system-level programming, embedded devices, game engines and other fields, and in these fields, C# is relatively rarely used. If you need to integrate SQLite into applications in these fields, it is more advantageous to use C language to develop.
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Fourth, the comparison between SQLite and other databases

4.1. Relational database MySQL

Both SQLite and MySQL are relational database management systems, but they differ in a few ways.

1. Database scale: SQLite is suitable for use on small personal or embedded devices. MySQL, on the other hand, is suitable for database management of medium and large applications.
2. Multi-user support: SQLite lacks the multi-user concurrency control function, and only one user can write or read data, so it is not suitable for high-concurrency web applications. And MySQL can support multi-threaded concurrent access.
3. Performance: SQLite is faster than MySQL in simple queries and single-user operations, but MySQL has better performance in complex queries and large concurrent requests.
4. Configuration and deployment: SQLite does not need to be installed and configured, and can be used only by introducing library files; while MySQL requires installation and configuration, and requires a dedicated server and administrator to maintain.
5. Extensibility: MySQL supports extending functions through plug-ins, but SQLite does not.
6. Security: MySQL has better security features, such as authority management, encrypted transmission, etc. And SQLite is relatively rare as it is usually used for local storage and lightweight applications.
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4.2. Relational database PostgreSQL

SQLite is a lightweight embedded relational database suitable for small applications. PostgreSQL is a mature relational database management system with more advanced features and functions.

1. Database size limit: SQLite has a database size limit of 2GB, while PostgreSQL has no explicit database size limit.
2. Concurrency control: PostgreSQL adopts MVCC (multi-version concurrency control) technology, which can effectively handle data read and write operations in a high-concurrency environment. SQLite uses a simple read-write lock mechanism.
3. Supported data types: PostgreSQL supports more data types, such as arrays, JSON, etc. SQLite only supports basic data types.
4. Engine support: PostgreSQL supports multiple storage engines, such as B-tree, Hash, GiST, etc. And SQLite only has its own storage engine.
5. Scalability: PostgreSQL has high scalability, new functions can be added through plug-ins, and multiple programming language interfaces are supported. However, SQLite has relatively little scalability and can only be extended through the C language interface.

If you need to handle large-scale data and high concurrent requests, or need more advanced features and scalability, then PostgreSQL is a better choice. And if you're just dealing with small applications, SQLite is a more lightweight option.

4.3. Non-relational database MongoDB

1. Data Model: SQLite is a relational database that uses tables to store data. It supports the SQL query language and has ACID transaction support. MongoDB is a document database that uses collections to store data. It stores data using the JSON format, which can easily represent complex data structures.
2. Scalability: SQLite is designed as a stand-alone database and does not support distributed deployment. MongoDB supports distributed deployment and performs well in large-scale, high-concurrency applications.
3. Performance: Since SQLite is a local file system database, reading and writing are very fast. It is fine for small applications, but can be bottlenecked for larger applications. The performance of MongoDB depends on the cluster environment and configuration, but it is generally more suitable for processing large amounts of data than SQLite.
4. Storage space: Since MongoDB stores data in JSON format, it usually requires more disk space than SQLite. But when dealing with large data, MongoDB's compression mechanism can save a lot of storage space.
5. Database management: SQLite only needs to install one file to use, which is very simple. MongoDB, on the other hand, requires a server to be installed and configured, which may require some technical knowledge.

SQLite is more suitable for small applications and stand-alone use, while MongoDB is more suitable for large applications and distributed environments.

4.4. Non-relational database Redis

1. Data storage method: SQLite is a relational database that uses SQL as a query language and stores data in tables; while Redis is a key-value storage database that does not support SQL and stores data in the form of key-value pairs.
2. Data type: SQLite supports a variety of data types, including strings, integers, floating point numbers, date and time, etc.; while Redis only supports simple string types.
3. Data processing speed: Since Redis is an in-memory database, it is faster than SQLite. SQLite needs to read data from disk, while Redis stores data in memory and can read data quickly.
4. Connection concurrency: SQLite can only support one connection, so in a high-concurrency environment, performance problems may occur. And Redis can handle multiple connection requests at the same time, which can meet the requirements of high concurrency.
5. Data security: SQLite supports transaction processing and ACID properties to ensure data integrity and consistency. However, Redis does not support transaction processing and ACID properties, which may lead to data risks.
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5. Application of SQLite in actual projects

1. Mobile application development: In mobile application development, SQLite is usually used to store and manage application local data, such as user information, configuration information, cache data, etc. It can easily handle large amounts of data and supports complex query and sorting operations. In addition, as one of the core components of mobile applications, SQLite can also be used in conjunction with other technologies and frameworks, such as ORMLite, GreenDAO, Room, etc., to improve development efficiency.
2. Desktop application development: SQLite is widely used in desktop application development. It can provide reliable local data storage and management functions while maintaining high efficiency and flexibility. Such as database management tools, email clients, chat programs, etc.
3. Web application development: The application of SQLite in web development is very flexible, it can provide reliable local data storage and management functions, while maintaining high efficiency and flexibility. But it is important to note that for large web applications, more powerful database solutions are usually required to meet the needs. Such as blog platform platform.

6. An example of using SQLite in c language

Official download address of SQLite source code: Download
The following is a basic C language program for connecting to SQLite database, creating tables, inserting data and querying data:

#include <stdio.h>
#include <stdlib.h>
#include <sqlite3.h>

int main(void) {
    
    
  sqlite3 *db;
  char *err_msg = 0;

  int rc = sqlite3_open("test.db", &db);

  if (rc != SQLITE_OK) {
    
    
    fprintf(stderr, "无法打开数据库: %s\n", sqlite3_errmsg(db));
    sqlite3_close(db);
    return 1;
  }

  char *sql = "CREATE TABLE IF NOT EXISTS users(id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, age INT);";

  rc = sqlite3_exec(db, sql, 0, 0, &err_msg);

  if (rc != SQLITE_OK ) {
    
    
    fprintf(stderr, "无法创建表: %s\n", err_msg);
    sqlite3_free(err_msg);
    sqlite3_close(db);
    return 1;
  }

  char *insert_sql = "INSERT INTO users(name, age) VALUES('Tom', 20);"
  
  rc = sqlite3_exec(db, insert_sql, 0, 0, &err_msg);

  if (rc != SQLITE_OK ) {
    
    
    fprintf(stderr, "无法插入数据: %s\n", err_msg);
    sqlite3_free(err_msg);
    sqlite3_close(db);
    return 1;
  }

  char *select_sql = "SELECT * FROM users;"

  sqlite3_stmt *stmt;

  rc = sqlite3_prepare_v2(db, select_sql, -1, &stmt, 0);

  if (rc == SQLITE_OK) {
    
    
    while (sqlite3_step(stmt) == SQLITE_ROW) {
    
    
      int id = sqlite3_column_int(stmt, 0);
      char *name = sqlite3_column_text(stmt, 1);
      int age = sqlite3_column_int(stmt, 2);
      printf("id: %d, name: %s, age: %d\n", id, name, age);
    }
  } else {
    
    
    fprintf(stderr, "无法查询数据: %s\n", sqlite3_errmsg(db));
  }

  sqlite3_finalize(stmt);
  sqlite3_close(db);

  return 0;
}

First connect to the database (if it does not exist, a new database will be created), then create a table named users, and insert a piece of data, and finally query all the data and output. Note that the SQL query statement can be modified to filter and sort results, etc., as desired.

7. Conclusion

Advantages of SQLite:

1. Serverless architecture for easy integration and deployment.
2. Lightweight: The SQLite library is only a few hundred KB in size and can be used on resource-constrained devices.
3. Supports standard SQL language, providing high scalability and flexibility.
4. Provides transaction support to ensure data integrity and consistency.
5. Support interfaces of multiple programming languages, including C, Java, Python, etc.

Advantages of C language:

1. C language is an efficient and fast system-level language that can directly access underlying hardware resources.
2. C language has a wide range of applications, including embedded systems, operating systems, game development, etc.
3. C language has a rich algorithm and data structure library, which can easily realize complex data processing and calculation functions.
4. C language is highly portable and can be compiled and run on different platforms.
5. C language supports process-oriented and object-oriented programming paradigms, and you can choose the appropriate programming method according to your needs.

The future development trend of SQLite:

1. Support for more types of data. At present, the data types supported by SQLite are relatively limited, and support for unstructured data types such as JSON and XML may be added in the future.
2. Further optimization of performance. SQLite is already a very fast and efficient database, but its performance can be improved through further optimization in the future, such as using more advanced algorithms and techniques, and making better use of modern computer hardware resources.
3. Improve concurrency performance. The current concurrency performance of SQLite is relatively weak, and a better concurrency control mechanism may be introduced in the future to improve concurrency performance.
4. Support for more platforms and languages. SQLite has been widely used in various platforms such as PCs and mobile terminals, and may support more platforms and programming languages ​​in the future to meet the needs of different scenarios.
5. Better security and reliability. The security and reliability of SQLite have been widely recognized, and work in this area may continue to be strengthened in the future, such as supporting better encryption mechanisms and transaction processing.

The future development trend of SQLite mainly focuses on the continuous improvement of performance, reliability, security and functions to meet the needs of different scenarios and expand the scope of application.