The column definition clause of the CREATE TABLE statement defines the table column elements.
A name and a data type must be specified for each column defined for a table.
Here is an example that creates a table called employee with three columns:
CREATE TABLE employee (deptno INTEGER ,name CHARACTER(23) ,hiredate DATE);
Each column can be further defined with one or more optional attribute definitions. The following attributes are also elements of the SQL column definition clause:
- Data type attribute declaration, such as NOT NULL, FORMAT, TITLE, and CHARACTER SET
- COMPRESS column storage attributes clause
- DEFAULT and WITH DEFAULT default value control clauses
- PRIMARY KEY, UNIQUE, REFERENCES, and CHECK column constraint attributes clauses
Here is an example that defines attributes for the columns in the employee table:
CREATE TABLE employee (deptno INTEGER NOT NULL ,name CHARACTER(23) CHARACTER SET LATIN ,hiredate DATE DEFAULT CURRENT_DATE);