The cells in a table's horizontal plane constitute rows; the cells in the vertical plane constitute columns. The row is the unit for performing operations on a table. Each row consists of data entries from one or more columns. Each column is given a column name. When an operation is performed on a table, you identify the position of an item in a row by its column name. Figure 3-4 shows an example of a table.

Figure 3-4 Example of a table

Explanation

This example illustrates the structure of an inventory table (the table name is STOCK). The columns are defined with the CREATE TABLE in the definition SQL. Following is the definition of the STOCK table's columns:

 
CREATE TABLE STOCK
   (PCODE CHAR(4),
    PNAME NCHAR(8),
    COLOR NCHAR(1)
    PRICE INTEGER,
    SQUANTITY INTEGER);

A data type must be specified for each column and for each attribute comprising an abstract data type. Data types are classified broadly as predefined data types and user-defined data types. A predefined data type is provided by HiRDB. A user-defined data type is defined by a user as needed. Table 3-3 lists the available data types.

Table 3-3 Available data types

Classification		Data type	Data format
Predefined	Numeric data	INTEGER	Integer
		SMALLINT	Integer
		LARGE DECIMAL	Fixed point
		FLOAT	Double-precision floating point
		SMALLFLT	Single-precision floating point
	Character data	CHARACTER	Fixed-size character string
		VARCHAR	Variable-size character string
	National character data	NCHAR	Fixed-size national character string
		NVARCHAR	Variable-size national character string
	Mixed character data	MCHAR	Fixed-size mixed character string
		MVARCHAR	Variable-size mixed character string
	Date data	DATE	Date
	Time data	TIME	Time
	Time-stamp data	TIMESTAMP	Precision for time-stamp data in floating-point seconds
	Date interval data	INTERVAL YEAR TO DAY	Date interval
	Time interval data	INTERVAL HOUR TO SECOND	Time interval
	Large object data	BLOB	Binary data string
	Binary data	BINARY	Binary data string
	Boolean data	BOOLEAN	Boolean value
User-defined	Abstract data type

: Not applicable

Data types are specified when a table is created with the CREATE TABLE of the definition SQL. The data type for an attribute comprising an abstract data type is specified with the CREATE TYPE of the definition SQL. For details on abstract data types, see Section 3.5 Expansion into an object relational database.