Basic Concepts and Terminology
- Table and Field Names
- Data Dictionary
- Filter Expression
- Memo Field
- Order Criteria
- Selection Criteria
- The Relationship of Tables to Forms, Browses, and Dialog Boxes
Information in an Alpha five database is stored in one or more files called tables. Each table consists of a multiple records, where each record represents one person, inventory item, transaction, etc.
Each record can have multiple fields, and each field contains one item of data of a specific type. For example, in a table of employees, there's one record for each employee, and individual items of information about that employee are contained in fields for that record. Information like name, address, social security number, etc. might make up the fields for the employee's record.
Alpha Five recommends that table names, field names, and paths to your files start with a letter (A-Z or a-z) and be composed of letters, numbers (0-9), and underscore (_) characters.
Below are some table related terms and concepts you should be familiar with before beginning with Alpha Five. They'll help you better understand the way Alpha Five stores and organizes data.
Refers to a linked collection of Forms and other layouts used together to accomplish a set of tasks without using the Alpha Five Control Panel.
A layout used to view and edit data in a table, but browses display multiple records in a tabular (spreadsheet) format of rows and columns.
A collection of tables, sets, and other objects used in a total data management solution.
Data dictionaries stories additional information that Alpha Five requires to display and process table data.
Alpha Five Expressions are like mathematical expressions composed of fields, functions, and operators. Expressions are used throughout Alpha Five to specify which records to select, how records should be ordered, and much more.
A portion of a record containing one piece of information. For example, an employee's first name might be one field in the employee's record. Field names can be up to 32 characters long. The widest field allowed is 255 characters. To overcome the column width limitation, there is also a memo field type.
A character expression that evaluates to a logical value and selects records from the table. Filter expressions are typed manually or created using the Filter Builder, Query Genie, or Expression Builder.
A layout in which you view, enter and change data in a table - typically one record at a time.
A list of table records in a particular order. When we search by index, Alpha finds the correct entry in the index file and then opens the corresponding record in the table. A table may have many indexes.
A value by which a record can be identified.
Generally used for printing mail Labels for envelopes. Labels are also useful for generating name tags, specimen labels, and such.
A general term for an ordered, visual representation of information.
Used for printing mail-style letters. You can also merge record information with text layouts to create personalized letters.
A memo field can store any type of alphanumeric data. The size and number of memo fields is limited by available disk space. An .fpt file manages the data for each memo field in a table. The .fpt file has its own built-in index that contains pointers to the disk locations where the memo data actually resides. If you edit a memo field, it will remain at the same disk location as long as it fits. If it has grown too large to fit, a new contiguous series of blocks will be allocated. The internal index (pointers) of the .fpt file will be updated to point to the new location of the memo, and also to mark the old location as "garbage". Notice how this differs from a regular, non-memo record. When you update a normal record it gets saved in exactly the same physical location it occupied before, no matter how many times you update it.
The process of retrieving records in a table into a particular sequence, like alphabetically by last name. Ordering is also referred to as sorting.
Parameters you specify to sort records.
A process you define that modifies data, performs calculations, imports data from different programs, exports data to a different file format, or generally manipulates data in some way.
A Collection of related data fields. For example, a table of employees would contain records of individual employees. Records are stored in no particular order. There is no practical architectural limit on the number of records in a table.
Reports are used to output data. You can design Reports with complex calculations, page headers and footers, graphics, and more.
Alpha Five looks through a table or set to find one or more particular records.
The act of choosing particular records from a table while filtering out others, like selecting records containing out-of-date products. Selecting is also referred to as filtering.
Parameters you specify for selecting records.
A collection of related tables, linked together in some logical way. For example, a set may link a table of departments to a table of employee names for each department based on department ID. A set is similar to a SQL JOIN query that unites fields from multiple tables into a single entity. A set does not contain any actual information, just a means to link existing tables.
Stores information in a database. A table is made up of rows (records) and columns (fields). Each table can contain an almost unlimited number of records while each record can contain up to 1,023 fields, storing individual bits of data.
Each form is bound to a table or set, and will display and directly manipulate data from only that table or set. Likewise, each browse is bound to a table or set, and will display and directly manipulate data from only that table or set. (It is possible to use Xbasic to retrieve, manipulate, or display data from other tables and sets.) Xdialog dialog boxes are different from forms and browses. They are not linked to any table or set but can display and manipulate data from multiple tables or sets.