Character Data Types
SQL-89 defined a CHARACTER(n) or CHAR(n) data type, which represents a fixed-length string of (n) printable characters, where (n) is always greater than zero. Some implementations allow the string to contain control characters, but this is not the usual case. The allowable characters were usually drawn from ASCII or Unicode character sets and most often uses those collation sequences for sorting.
SQL-92 added the VARYING CHARACTER(n) or VARCHAR(n), which was already present in many implementations. A VARCHAR(n) represents a string that varies in length from 1 to (n) printable characters. This is important; SQL does not allow a string column of zero length, but you may find vendors who do, so that you can store an empty ...
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