STRING: It is a sequence of characters that can be expressed using single quotes (') as well as double quotes (").

VARCHAR: It is variable-length character type. It is defined using a length specifier, which specifies the maximum number of characters allowed in the character string. Its syntax is VARCHAR(max_length). The value of the varchar data type gets truncated during processing if necessary to fit within the specified length. While converting the string value to the varchar value, if a string value exceeds the length specifier, then the string gets silently truncated. The maximum length of varchar type is 65355.

CHAR: It is fixed-length character type. It is defined in the same way as the varchar type. If the value is shorter as compared with the specified length, then the value is padded with trailing spaces to achieve the specified length. The maximum length of the char type is 255.