(I have requested the moderators move this thread to Project Guidance)There are many kinds of SQL databases. Can you be more specific? Do you have LAMP or WAMP installed on the pc? What else will the Arduino be doing? What data will it send to the database?My recommendation at this point would be Wemos Mini. They are small, inexpensive, easy to use and has WiFi built in.
I am a new user, if I want to use arduion to connect SQL database of my PC by wireless，Which arduino and parts should I buy?
I want to know whether Arduino can write data to any kind database directly, rather than I need to build a app in my PC to write data to database.
There is an Arduino library that can connect directly to a MySQL database and store data into the database
Does it use WiFi or a serial connection, perhaps using Bluetooth?
(Being pedantic, WiFi is also a type of serial connection. The bits are sent at high speed, but they are still sent one-at-a-time!)
(the "P" in LAMP stands for PHP, which is a scripting language).
If you install LAMP/WAMP on your PC, this includes the MySQL database. There is an Arduino library that can connect directly to a MySQL database and store data into the database (the "M" in LAMP stands for MySQL).).
About the Arduino library that can connect directly to a MySQL database, How can I get it?
I gave you the name already.... as your Google-fu (or reading) skills appear lacking, hereby the link. Just install this: https://github.com/ChuckBell/MySQL_Connector_Arduino