Characteristic of the table

Characteristic Type given (DataType)

Cвойство Type given (DataType) for each column of the created table defines the type data, keeping in field of the table. Possible following importances characteristic Type given.

Importance	Description
Text	Text, which maximum length is equal 255 symbols or is defined by importance characteristic Size of the field (FieldSize) (is used by default)
Memo	The Text, which maximum length is equal 64 000 bytes. Fields of this type can be not indexed
Number	Any numbers. For reception of the more detailed information see description a characteristic Size of the field
Date/Time	Dates and time, referring to year with 100 on 9999, inclusive
Currency	Numbers, keeping accurate to 15 signs in whole and before 4 signs in fractional part
AutoNumber	The Number, automatically enlarged at accompaniment in table each new record. Fields of this type does not subject to to change
Yes/Now	Logical importances, as well as field, which can contain one of two things possible importances. Fields of this type can be not indexed
OLE Object	The Object (for instance, spreadsheet Microsoft Excel or drawing Microsoft Draw) created by other application. The Maximum size approximately one gigabyte. Fields of this type can be not indexed

This characteristic can be determined only by means of column Type given in window of the constructor of the tables. It is absent in form characteristic; his(its) it is impossible define by means of макроса or Visual Basic.

For each field of the table necessary without fall to assign the type data. Given only one type can be kept In each field.

Change the type of the field after entering given in table can bring about loss data

Characteristic Size of the field (FieldSize)

Will Assign the maximum size data, which can be in given field.
This characteristic can be determined in form characteristic field only. It Is Recommended use as possible smaller importance characteristic Size of the field since data processing the smaller size is executed quicker and requires memories less.

• Transformation of greater importance characteristic Size of the field to smaller in table, which already contains data, can bring about loss data
• Impossible canceal changes to model of the table after his(its) conservations in mode of the Constructor

Characteristic Empty lines (AllowZeroLength)

The Application field of the tables (text and MEMO). Indicates, possible carry in given field of the line of the zero length ( ). Possible following importances characteristic Empty lines:

• Yes - if in given field possible to enter the line of the zero length;
• No - if in given field it is impossible enter the line of the zero length (is used by default).

To carry in field line zero length, will enter two quotation marks( ).

Importances characteristic Empty lines and Obligatory field (Required) possible use for distinguishing nonexistent given (keeping in the manner of lines of the zero length) and data, which exist, but an unknown (keeping in the manner of empty (Null) of importances). For instance, the database can contain the information about client, beside which no fax. If for field Fax characteristic Empty lines has importance Yes , characteristic Obligatory field has importance No , but importance characteristic Importance by default (DefaultValue) is left empty, that operator can enter two quotation marks to indicate that beside given client of no fax. But if field Fax is left empty (the number of the fax was not incorporated in general or was removed), signifies, possible, beside given client there is fax, however, his(its) number unknown.

The Characteristic Empty lines and Obligatory field do not hang the friend from friend. The Characteristic Obligatory field whole only indicates, possible carry in given field empty (Null) of importance. If characteristic Empty lines has importance Yes , signifies, in given field possible to enter the line of the zero length, regardless of importances characteristic Obligatory field.

Characteristic Signature of the field (Caption)

Indicates the text, which is displayed in connected with floor signature and is used as headline column in mode of the table.

The Length signature field, the forms or buttons can reach 255 symbols. The Signature of the field possible to define in window of the constructor of the tables or in window of the request (in list Characteristic of the field ).

Usually signature are used for image of the useful information. If signature of the bounded field is not determined, that as she is used name of the base field

Characteristic Gap by empty flap (IgnoreNulls)

Indicates, follows comprise of index of the field, containing empty (Null) of importance.
Execution of searching for in determined field of the table and sorting the record on this field possible to accelerate, having created index for this field. If indexed field can contain empty (Null) of importance, that possible install importance Yes characteristic of the object of the type Index Gap by empty flap , hereunder reduced a volume of the index.

Characteristic Indexed field (Indexed)

Defines the index on one field. Possible following importances characteristic Indexed field

Importance	Description
No	Does Not create index on given field (is used by default)
Yes (coincidences are Allowed)	Creates index on given to field
Yes (Coincidences are not allowed)	Creates unique index on given to field

This characteristic possible to define in form characteristic in window of the constructor of the tables (in list Characteristic of the field ). Besides, possible choose the command Indexes in menu TYPE or press the button Indexes on panels instrument. The window Indexes will appear On screen. After accompaniment of the index on one field in window Indexes characteristic Indexed field will automatically take importance Yes .

Use the characteristic Indexed field for speedup of the execution of searching for and sorting the record on one field of the table. The Indexed field can contain as unique, so and reiterative importances. The User can create how much are pleased index. The Indexes at conservation of the model of the table and are automatically updated when entering and change the record. The User can anytime add new or delete the unnecessary indexes in window of the constructor of the tables. If key of the table consists of one field, that MS Access automatically installs importance Yes (the Coincidences are not allowed) characteristic Indexed field for given field.

However indexes slow change, entering and removing data so is not recommended create the surplus indexes.

THE MEMO, logical and OLE-field can be not indexed. For making component index follows to use the window Indexes.

Characteristic Fixed column (FrozenColumns)

Returns the number a column, fixed in mode of the table. The Fixed column are situated in left part of table; their position is not changed under horizontal rolling of the table.

Importance characteristic Fixed column is fixed automatically at choice of the command to Fix the column in menu FORMAT. Importance this characteristic is an integer number, equal count;calculate;list column of the table, fixed by means of commands to Fix the column. The Area of the marking the record is always fixed so at фиксации one column characteristic Fixed column takes importance 2, at фиксации two columns 3 etc.

The author: Y.N.Antonov Is added: 24.06.2008