Call Level Interface Guide and Reference

Parameter Binding Offsets

When an application needs to change parameter bindings it can call SQLBindParameter() a second time. This will change the bound parameter buffer address and the corresponding length/indicator buffer address used. This can only be used with row wise array inserts, but will work whether the application binds parameters individually or using an array.

Instead of multiple calls to SQLBindParameter(), DB2 CLI also supports parameter binding offsets. Rather than re-binding each time, an offset can be used to specify new buffer and length/indicator addresses which will be used in a subsequent call to SQLExecute() or SQLExecDirect().

To make use of parameter binding offsets, an application would follow these steps:

1. Call SQLBindParameter() as usual. The first set of bound parameter buffer addresses and the corresponding length/indicator buffer addresses will act as a template. The application will then move this template to different memory locations using the offset.

2. Call SQLExecute() or SQLExecDirect() as usual. The values stored in the bound addresses will be used.

3. Set up a variable to hold the memory offset value.

   The statement attribute SQL_ATTR_PARAM_BIND_OFFSET_PTR points to the address of an SQLINTEGER buffer where the offset will be stored. This address must remain valid until the cursor is closed.

   This extra level of indirection enables the use of a single memory variable to store the offset for multiple sets of parameter buffers on different statement handles. The application need only set this one memory variable and all of the offsets will be changed.

4. Store an offset value (number of bytes) in the memory location pointed to by the statement attribute set in the previous step.

   The offset value is always added to the memory location of the originally bound values. This sum must point to a valid memory address.

5. Call SQLExecute() or SQLExecDirect() again. CLI will add the offset specified above to the locations used in the original call to SQLBindParam() to determine where in memory to find the parameters to use.

6. Repeat steps 4 and 5 above as required.

See the section Parameter Binding Offsets in SQLBindParam() for more information.

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