SQL is a special-purpose programming language designed to handle data in a relational database management system. A database server is a computer program that provides database services to other programs or computers, as defined by the client-server model. Therefore, a SQL Server is a database server that implements the Structured Query Language (SQL).
There are many different versions of Microsoft SQL Server, catering for different workloads and demands. A data centre version is tailored to higher levels of application support and scalability, while the Express version is a scaled down, free edition of the software.
1GB maximum memory used by the SQL Server Database Engine
The maximum size of each relational database is 10GB
SQL Agent is not included in Express. The SQL Agent is a background tool which enables administrators to automate tasks like backing up data, database replication setup, job scheduling, user permissions, and database monitoring.
The limit on the buffer cache for each instance is 1MB of RAM.
The relational database engine is restricted to the lesser of 1 socket or 4 cores.
PC requirement to install SQL standard version:
1) 32 GB ram, 10 TB HDD,
2) 4 socket or 24 core compute capacity,
3) i7 processor 64-bit,
4) windows 8 or above OS 64-bit licence version, MS-office.
Kindly find below attachment.