HP 3000 Manuals HP 3000 Manuals
At a Glance HP ALLBASE/BRW uses a relational model for manipulating data. The relational model looks at data as if it were in a table, with rows and columns. The model is concerned with data structure, data integrity, and data manipulation. All data is represented by explicit value. The table below represents a typical relational model for data: ------------------------------------------------------------------------------------------------------- | | | | | | | | CUSTOMER-NO | CUSTOMER-NAME | CITY | SALES-AREA | STATE | ZIPCODE | | | | | | | | ------------------------------------------------------------------------------------------------------- | | | | | | | | 223 | Nancy Watson | 1411 Oak | Roseville | CA | 95999 | | | | | | | | ------------------------------------------------------------------------------------------------------- | | | | | | | | 789 | Mike Barnes | 232 Benton Dr. | Cool | CA | 95888 | | | | | | | | ------------------------------------------------------------------------------------------------------- | | | | | | | | 456 | Frank Heartney | 111 Tudor Lane | Citrus Heights | CA | 95601 | | | | | | | | ------------------------------------------------------------------------------------------------------- When you work with the data, you select columns and qualify rows in one or more tables to create another table containing a specific set of rows and columns of values. In HP ALLBASE/BRW the rows are called records and the columns are items. For instance, in the sample table shown above, the column containing customer numbers is an item and each row containing customer information is a record. Wherever an item and a record meet, you have a value. For instance, Frank Heartney is the value for CUSTOMER-NAME in the record for customer number 456. However, unlike an ordinary table, the columns and rows are not arranged in any particular order in a relational database model. You define the relationship you want to exist in your table. Tasks for adding tables and defining relations are discussed in Chapter 6 . This chapter covers * about tables * about relations