Declaring Transaction Names

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Transaction names must be declared before they can be used. A name is declared as a host-language pointer. In C and C++, transaction names should be declared as long pointers.

The following code illustrates how to declare two transaction names:

EXEC SQL
BEGIN DECLARE SECTION;
isc_tr_handle t1;
isc_tr_handle t2;
EXEC SQL
END DECLARE SECTION;

Note:
In this example, the transaction declaration occurs within a SQL section declaration. While InterBase does not require that host-language variables occur within a section declaration, putting them there guarantees compatibility with other SQL implementations that do require section declarations.

Transaction names are usually declared globally at the module level. If a transaction name is declared locally, ensure that:

• The transaction using the name is completely contained within the function where the name is declared. Include an error-handling routine to roll back transactions when errors occur. ROLLBACK releases a transaction name, and sets its value to NULL.
• The transaction name is not used outside the function where it is declared.

To reference a transaction name declared in another module, provide an external declaration for it. For example, in C, the external declaration for t1 and t2 might be as follows:

EXEC SQL
BEGIN DECLARE SECTION;
extern isc_tr_handle t1, t2;
EXEC SQL
END DECLARE SECTION;

Advance To:

• Initializing Transaction Names