ODBCLINK/SE Reference Manual (36217-90410)

Appendix A Implementation Notes ODBCLink/SE Reference Manual
ODBCLink/SE
68 ©M.B. Foster Associates Limited 1995-2000
⊗ If you are in AUTOCOMMIT mode ON (this is the default option, set
through SQLSetConnectOptions and in ODBC Administrator), there is an
implicit Commit done whenever you fetch the last row. This is so that locks
held on the database by the open cursor are released. This may destroy other
open cursors. Note also that opening a table for the first time automatically
triggers various initialization calls that cause a commit to be done when
AUTOCOMMIT is ON.
⊗ If you are using prepared statements with substitution parameters to insert
or update you need not be concerned about this, as the prepared statement
will still be valid after a Commit, and you may bind new parameters and
SQLExecute again with no problem. Prepared statements are SQL
statements with question marks ‘?’ that you SQLPrepare and then call
SQLBindParam or SQLBindCol.
If you wish to use multiple statements, but are not writing your own SQL (i.e. you are using a 4GL application) you
can tell ODBCLink/SE to have SQLGetInfo report more than 1 statement per connection. To do this, modify the
ODBC.INI or the registry manually, and add a new parameter “MAXSTMT=50".
ALLBASE/SQL and IMAGE/SQL Restrictions on the ODBC Gram-
mar
The following table summarizes the ALLBASE/SQL restrictions on the ODBC grammar:
ALLBASE/SQL provides a DATETIME data type that is similar to TIMESTAMP.
ALLBASE/SQL does not implement optimistic locking. Optimistic locking means that the DBMS does not lock data
until just before an update is made, thus improving concurrency because locks are not held for long.
Using the ANSI Character Set
The HP3000 and HP9000 both use the default ROMAN8 character set. Most applications running under Microsoft
Windows use the 8-bit ANSI (ISO 8859/1) character set to provide support for Western European languages
(including American). The first 127 characters are the same for both ROMAN8 and ANSI character sets, so only the
extended and special characters are different.
If your PC client application uses these extended or special characters, then the data from the database server must be
converted from ROMAN8 to ANSI, and the data returning to the database server must be converted from ANSI to
ROMAN8. To activate the conversion, select the “Roman8 to PC-ANSI translation DLL during the data-source
setup. The conversion takes place on the PC client.
Bind variables of datatype CHAR and VARCHAR are also converted. A bind variable in an SQL statement is
associated (bound) to variables defined in a program. A bind variable is another name for a dynamic parameter.
Statement Programming Considerations
CREATE TABLE UNIQUE PRIMARY KEY must follow NOT NULL
DROP TABLE ALLBASE/SQL does not provide CASCADE or RESTRICT
REVOKE ALLBASE/SQL does not provide RESTRICT.