Microsoft Access - Number Data Types

Data Type Description Decimal precision Storage size
Byte Numbers from 0 to 255 (no fractions).
Use Number | Byte in preference to Yes/No (True=-1, False=0)
None 1 byte
Decimal Numbers from -10^28-1 through 10^28-1 (.mdb) 28 12bytes
Integer Numbers from -32,768 to 32,767 (no fractions). None 2 bytes
Long Integer (Default) Numbers from -2,147,483,648 to 2,147,483,647 (no fractions). None 4 bytes
Single 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 Numbers from
-1.79769313486231E308 to -4.94065645841247E–324
for negative values and from
4.94065645841247E-324 to 1.79769313486231E308 for positive values.
15 8 bytes
Replication ID Globally unique identifier (GUID) N/A 16 bytes

SQL Server

If an Access database is upsized to SQL Server, Yes/No fields (tickboxes) will be converted to bit fields. These will give an error in Access if any row contains a NULL: This record has been changed by another user since you started editing it. If you save the record, you will overwrite the changes the other user made.
To resolve this, assign a default value of (0) on all bit fields and update any existing rows to either 0 or 1.


Compatibility Between the 32-bit and 64-bit Versions of Office 2010 - MSDN

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