This is false that only numeric data types can be added and subtracted in SQL.
SQL Data Types:
Each column in the database table is required to have a name and data type. A SQL developer must decide what type of data that will be stored inside each column while creating a table. The data type is a guideline for SQL to understand what types of data are expected inside of each column and it also identifies how the SQL will interact with the data that is stored.
Example of SQL data types:
Few popular examples of SQL data types are;
A FIXED length string that contains the letters numbers and special characters. The size parameter defines the column length in characters that can be from 0 to 255.
Hold a string with a maximum length of 65, 535 bytes.
Zero is considered as false and non-zero values are considered as true.
A medium integer. The signed range is from -2417483648 to 2147483647. The unsigned range is from 0 to 4294967295. The size parameter specifies the maximum display width which is 255.
A date format YYYY-MM-DD. The supported range us form ‘1000-01-01’ to ‘9999-12-31’.