You must specify a data type for each column in a table when you define the columns with CREATE TABLE or ALTER TABLE. The data type defines the type of values that you can enter in the column. After you have defined a table, you can use ALTER TABLE to a certain extent to change the existing data type.
BLOBs (Binary Large Objects) are based on existing data types in SESAM/SQL and are therefore not a new data type in themselves. Information on their structure and how to use them can be found in the chapter “SESAM-CLI” and in the “ Core manual”.
Excluding the NULL value
If you want to exclude the NULL value for a column, you must specify this when you define the table with CREATE TABLE or ALTER TABLE by including a NOT NULL constraint (see section “Column constraints”).
Multiple columns
All the elements in a multiple column have the same data type. You can use any data type except VARCHAR and NVARCHAR for a multiple column. The dimension of a multiple column indicates the number of elements; it is specified when the data type is assigned and must be between 1 and 255.