ACC: Factors When Opening Attached ODBC Tables in MS Access
ID: Q103255
|
The information in this article applies to:
-
Microsoft Access versions 1.0, 1.1, 2.0
SUMMARY
Advanced: Requires expert coding, interoperability, and multiuser skills.
This articles describes the factors that determine whether Microsoft
Access will open an attached ODBC table in read-only mode or in
read/write mode.
MORE INFORMATION
The following are three factors that can cause Microsoft Access to
open an attached ODBC table in read-only mode:
- When the attached table does not have a unique index in the data
source.
Microsoft Access is built on a keyset-driven cursor model, in which
data is retrieved and updated based on key (or unique index)
fields. If the key does not exist in the back-end table, Microsoft
Access opens the table in read-only mode and the user is not able
to modify the data.
- If the ODBC data source is set to read-only by either the DBMS
security system or the network security system.
Microsoft Access determines this status by calling the ODBC
application programming interface (API) SQLGetInfo() with
fInfoType=SQL_DATA_SOURCE_READ_ONLY. If *rgbInfoValue=TRUE, then
the data source is read-only; as a result, the attached table is
opened in read-only mode.
- If cursors are treated by the ODBC driver in a certain way. When a
transaction is committed or rolled back, the ODBC driver can:
- Preserve the cursor.
- Close the cursor.
- Close and delete the cursor.
A cursor is a construct that is defined to point to a record (or
set of records) in the table. The data is then manipulated by
referencing the cursor.
If the driver exhibits behavior 3, Microsoft Access opens the
table in read-only mode. To determines this, Microsoft Access
first calls the ODBC API SQLGetInfo() with fOption=SQL_TXN_CAPABLE.
If
*rgbInfoValue=TRUE,
Microsoft Access calls SQLGetInfo with
fInfoType=SQL_CURSOR_COMMIT_BEHAVIOR
followed by
fInfoType=SQL_CURSOR_ROLLBACK_BEHAVIOR.
If either of these values is 0, the ODBC driver closes and deletes
the cursors on committals or rollbacks.
Keywords : kbusage OdbcOthr
Version : 1.0 1.1 2.0
Platform : WINDOWS
Issue type : kbinfo
|