• ENUM
• NUMBER, NUMBER(i), NUMBER(i,j)
• Formatted numbers, i precision, j scale
• (number of digits total, after decimal point)
• Character-string
• CHAR(n) - n is length
• VARCHAR2(n) - n is max
• DESCRIBE output example
• Multi-database comparison of Datatypes
• Database legacy: limited storage necessitated efficient storage
• Does it need to be efficient anymore?

You might consider all SQL types as being conceptually similar to attribute types in the relational model, although in reality the implementation of these types in a DBMS only approximates the mathematical purity of unordered domain sets etc.