The SQL server has many inbuilt string functions.

Firstly, the A-S-C-I-I simply stands for American Standard Code for Information Interchange.

It serves as a character and coding standard from modern computers.

So for example, when we input an expression of type fixed to length string data or even a variable length string data, it simply returns the A-S-C-I-I value for the specific character.

And then the char, which simply, uh, stands for a character, returns the character based on the A-A-C-I-I value.

And the Char Index returns the position of a substring in a certain string that we input.

The Concat function simply adds two different strings or multiple strings together.

And similarly, the replicate just replicates a string, a specified number of times.

The SDR function simply returns a number as a string.

These are some important string types, but it's not limited to what is mentioned right now. There are a lot more string types available in SQL.