Table

Notion of the table

MS Access supports the relational model data i.e. the database consists of ensemble of the interconnected relations, each attitude corresponds to the separate table.

The Tables consist of lines and column. The Column of the table reflect the general characteristic or features object real world, which are prototyped with use given tables. One column selects For each characteristic user. The Lines of the table correspond to the different copy real object and are identified record.

Advisable for each table to define the primary key column or set column uniquely defining line of the table.

Making the table

Previously than create the table, necessary to open the database, in which MS Access will keep this table. Then in window database follows to choose the bookmark TABLE , press the button "to Create", and in opened window of the dialogue to choose the necessary mode of the making the table: Master or Constructor.

MS Access offers the big amount of the tables-example, containing given from different areas. In list Sample by flap will appear the list by flap data, which possible select and place in list Field of the new table . If name by flap it is not enough информативны, their possible change.

Hereinafter in mode Master MS Access offers to install the primary key.

For change the structure of the table necessary to use the cut Constructor. The Fields of the table are located friend under the other. For each field name, type and description. The Field of the primary key of the table, as a rule, can have a type given "Counter" (AutoNumber). This type data guarantees that during entering given MS Access automatically numbers the line of the table in increasing sequences.

In mode of the Constructor possible to change the available fields and add new. If table already contains the data then when change the structure of the table they get lost only in exclusive events. MS Access warns about this corresponding to message.

In именах by flap is forbidden use the symbols ! , . , [ , ] . The Maximum length of the name 64 symbols. Is Not recommended use in именах by flap gaps since hereinafter can incorrect be executed requests.

As type field data possible to use the following standard types: numeric, text, counter, field MEMO, money, logical, date/time, field of the object OLE. For each field possible to enter the free commentary, pertaining data to field. The Typical commentary is a description of the purpose of the field.

For each field possible to assign the additional features. For instance, for text flap possible to define the size of the field, but for numeric to define the length of the class net and amount category after comma.

When making the tables by means of Constructor MS Access will automatically assign the primary key. To define in quality of the primary key other set by flap, follows to select the corresponding to field and press the pictograph to DEFINE the KEY on panels instrument. During entering given in field, determined as primary key, MS Access automatically keeps a check on that to were entered only unique importances. THE MEMO-field and field of the object OLE can not be a primary key.

Table as object of the designing in MS Access

Each table has a characteristic, which importances define her(its) type and behaviour. Below all available characteristic of the table are brought

1. AllowZeroLength	8. FieldSize	15. Required
2. DataType	9. Format	16. SortOrder
3. Caption	10. IgnoreNulls	17. Unique
4. DecimalPlaces	11. FrozenColumns	18. ValidationRule
5. DefaultValue	12. Indexed	19. ValidationText
6. Description	13. InputMask
7. FieldName	14. Primary

The Note: Characteristic DataType applicable only to table, but characteristic Description to table, fields of the tables and index. The Characteristic FrozenColumns applicable only to table in mode of the table. The Rest characteristic applicable to fields of the tables and index and can be determined in mode of the constructor of the tables.

The author: Y.N.Antonov Is added: 23.06.2008