What is data definition language? Explain it in detail?

The SQL DDL allows specification of not only a set of relations, but also information after each relation, containing

a) The schema for each relation

b) The domain of values associated with each attribute

c) The integrity constraints

d) The set of indices to be maintained for each relation

e) The security and authorization information for each relation

f)  The physical storage structure of each relation on disk

  Domain Types in SQL

Char(n),

varchar(n), int, small int, numeric(p,d), real, double, precision,

f loat(n), date, time, timestamp.

Schema Definition in SQL

a) Primary key

b) Check