Data Types in SQL - Character

CHARACTER or, synonymously, CHAR, for character strings. When this type is to be the declared type of something (e.g., a column), the permissible values are further constrained by a maximum length specification given in parentheses and optionally by the key word VARYING, indicating that values shorter than the maximum, including the empty string '' , are also permissible. Examples: CHAR(5) for strings of five characters only, CHARACTER VARYING (100), which can be abbreviated to VARCHAR(100), for strings of up to one hundred characters. The last two are alternative spellings for the same declared type.

The type CHARACTER LARGE OBJECT, or CLOB, allows for inclusion of strings that are longer than the longest supported by the other CHARACTER types. Note that in the terminology of the theory book CHARACTER is a kind of type generator. The key word does not of itself denote a type, but only does so when qualified by a length specification. A similar remark applies to some of the other type names used in SQL.