PostgreSQL Installation and Creating Your First Database | SQL Shell & PgAdmin4

In client-server architecture, multiple client systems can access the database simultaneously. When a user sends a request, it goes through the network server to the database, and the result is sent back to the user system. Multiple users can send the same request simultaneously, and the database server processes all requests at the same time, sending results back to all systems.

The client-server architecture separates components across different servers: (1) Database Server - stores the information base using supported SQL servers (Microsoft SQL Server, PostgreSQL, IBM DB2, Oracle), (2) 1C Server - an additional software component that manages business logic and interacts with the database server, (3) Web Server (optional) - handles web-based client connections. The 1C Server processes requests, converts them to SQL queries, retrieves data from the database, performs additional processing, and returns results to clients. This architecture supports high scalability and security.

The client-server architecture in 1C Enterprise is a three-level system designed for enterprise use: (1) Client application running on user computers, (2) 1C Server cluster that processes requests, and (3) Database server (СУБД) that stores data. When users perform actions, requests flow from client to server, then to database, and back. This architecture enables scalability by allowing load distribution across multiple servers, making it easier to upgrade hardware than file-based systems. 1C supports four database servers: Microsoft SQL Server (recommended for beginners), PostgreSQL (free but requires configuration), IBM DB2, and Oracle Database. Communication uses TCP/IP protocol, but Shared Memory protocol provides 20-30% performance improvement when 1C Server and SQL Server run on the same machine.

Client-server architecture consists of clients (software sending requests) and servers (software receiving and processing requests). When installing database software, two components are installed: the database itself (server) and the database application (client). SQL (Structured Query Language) is the standard language for database communication. JDBC enables Java applications to communicate with databases using this architecture, whether both components run locally or remotely across networks.

Client-server architecture is a three-tier system where the client handles user interface and basic validation, the server processes business logic and maintains application code, and the database stores and manages data; this separation enables scalability, centralized maintenance, and security, though it introduces single points of failure that can be mitigated through clustering and load balancing, with testing requiring examination of all three components to ensure proper functionality and security.

CLI (Command Line Interface) is the black screen interface for keyboard-only computer operation, offering advantages over GUI: faster operations, simpler learning curve, and more powerful system-level capabilities. CLI operates through a two-phase cycle: users type commands and press enter, then the computer executes and displays results. WSL (Windows Subsystem for Linux) enables UNIX commands on Windows. Core navigation commands include: LS (list) displays directory contents; CD (change directory) moves between directories; MKDIR (make directory) creates new directories; TOUCH creates empty files; CTRL+L clears screen. Understanding relative paths (from current location) versus absolute paths (from root) is essential for navigation.

A command line interface (CLI) is a text-based user interface for running programs, managing files, and interacting with operating systems. Users enter text commands (input) and receive text output. Common CLIs include Bash for Unix/Linux, Z shell for Mac, Windows Command Prompt, and PowerShell. CLI commands follow a standard syntax: command (directive), options/flags (modify behavior), and arguments (parameters). Core navigation commands include pwd (display absolute path), ls (list directory contents with -l for detailed metadata), and cd (change directory with .. to return to parent or cd alone to return home). File and directory management commands include mkdir (create directories with -v for confirmation), touch (create empty files), cp (copy files/folders with -r for recursion), mv (move/rename files/folders), and rm (remove files/folders with -r for recursion). These commands form the foundation for efficient system navigation and file management.

Command Line Interface (CLI) is a text-based user interface where users type commands to instruct computers. The shell acts as a translator between user commands and the operating system. Windows Command Prompt (cmd) and PowerShell are the primary interfaces. Basic navigation commands include 'dir' to list files, 'cd' to change directories, and 'cd ..' to move up one level. File management commands include 'mkdir' to create folders, 'rmdir' to remove folders, 'type nul > filename.txt' to create empty files, 'echo' to add content, 'ren' to rename, 'copy' to duplicate, 'move' to relocate, 'del' to delete files, and 'cls' to clear the screen. Users can run programs by typing the program name followed by the filename, and open editors like VS Code using 'code .'

The command line interface (CLI) is an alternative method for operating computers, representing the original way computers were controlled before graphical user interfaces became standard. Different operating systems have different command line interfaces: Windows uses Command Prompt, while Linux and macOS share similar command sets. For Windows users wanting Linux commands, emulators like Commander (Konsole) provide a full Linux environment. The echo command is universal across platforms. File system navigation uses hostname for system identification, pwd for current directory on Linux/macOS, and cd for directory navigation. The man command provides documentation on Linux/macOS, while Windows uses help commands. The ls command lists directory contents on Linux/macOS, with Windows using dir instead.

Fundamental CLI commands include: CD (change directory) to move between folders, LS or DIR (list directory contents) to view what's inside folders, and MDIR or MD (make directory) to create new directories. These commands work across different operating systems: Terminal on Mac OS, Command Prompt (CMD) on Windows, and PowerShell on Windows. The basic workflow involves typing the correct command and pressing enter to execute it.

Localhost is a special hostname that refers to the local computer itself within a network context. It is an alias for the IP address 127.0.0.1, which represents the computer's own network interface. When accessing localhost:3000, you are accessing a service running on your own computer. Ports are network communication channels that allow multiple services to run simultaneously on the same computer. Port 80 is the default port for HTTP web traffic, while port 443 is used for HTTPS (encrypted HTTP).

Localhost (127.0.0.1) is a special host address that refers to the local machine itself. When a database runs on the same computer as the application, localhost is used instead of the actual IP address. For PostgreSQL databases, the default port is 5432, which differs from the default web server ports.

Localhost (127.0.0.1) is a reserved IP address that represents the computer's own network interface. When applications run on localhost, they are running locally on the same machine rather than on a remote server. Ports are like virtual doors that allow different applications to communicate on the same computer, with each application typically assigned a specific port number.

Localhost (127.0.0.1) is a special IP address that refers to the local machine, allowing applications to communicate with themselves. Network ports are numbered channels (0-65535) that applications use to communicate over the network. Ports below 1024 are typically reserved for system services, while higher ports are available for user applications. When a web server starts, it listens on a specific port for incoming connections, and clients connect to that port to communicate with the server.

Ports are network addresses that allow programs to communicate with each other. When running a server, you specify which port it should listen on (e.g., port 3000). The server waits for incoming connections on that port. Localhost refers to the local computer (the machine running the server). When accessing 'localhost:3000', you are accessing a service running on your own computer. Common ports include 80 (HTTP), 443 (HTTPS), and 3000 (commonly used for development).