You can use the FieldSize property to set the maximum size for data stored in a field set to the Text, Number, or AutoNumber data type.
Setting
If the DataType property is set to Text, enter a number from 0 to 255. The default setting is 50.
If the DataType property is set to AutoNumber, the FieldSize property can be set to Long Integer or Replication ID.
If the DataType property is set to Number, the FieldSize property settings and their values are related in the following way.
| Setting | Description | Decimal precision | Storage size |
|---|---|---|---|
| Byte | Stores numbers from 0 to 255 (no fractions). | None | 1 byte |
| Decimal | Stores numbers from -10^38 -1 through 10^38 -1 (.adp) Stores numbers from-10^28 -1 through 10^28 -1 (.mdb) |
28 | 12bytes |
| Integer | Stores numbers from –32,768 to 32,767 (no fractions). | None | 2 bytes |
| Long Integer | (Default) Stores numbers from –2,147,483,648 to 2,147,483,647 (no fractions). | None | 4 bytes |
| Single | Stores numbers from –3.402823E38 to –1.401298E–45 for negative values and from 1.401298E–45 to 3.402823E38 for positive values. |
7 | 4 bytes |
| Double | Stores numbers from –1.79769313486231E308 to –4.94065645841247E–324 for negative values and from 1.79769313486231E308 to 4.94065645841247E–324 for positive values. |
15 | 8 bytes |
| Replication ID | Globally unique identifier (GUID) | N/A | 16 bytes |
You can set this property only from the table's property sheet.
To set the size of a field from Visual Basic, use the DAO Size property to read and set the maximum size of Text fields (for data types other than Text, the ADO Type property setting automatically determines the Size property setting).
Note You can specify the default field sizes for Text and Number fields by changing the values under Default Field Sizes on the Tables/Queries tab, available by clicking Options on the Tools menu.
Remarks
You should use the smallest possible FieldSize property setting because smaller data sizes can be processed faster and require less memory.
Caution If you convert a large FieldSize setting to a smaller one in a field that already contains data, you might lose data. For example, if you change the FieldSize setting for a Text data type field from 255 to 50, data beyond the new 50-character setting will be discarded.
If the data in a Number data type field doesn't fit in a new FieldSize setting, fractional numbers may be rounded or you might get a Null value. For example, if you change from a Single to an Integer field size, fractional values will be rounded to the nearest whole number and values greater than 32,767 or less than –32,768 will result in null fields.
You can't undo changes to data that result from a change to the FieldSize property after saving those changes in table Design view.
Tip You can use the Currency data type if you plan to perform many calculations on a field that contains data with one to four decimal places. Single and Double data type fields require floating-point calculation. Currency data type fields use a faster fixed-point calculation.