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MySQL NDB Cluster API Developer Guide
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2.3.21.11 NdbEventOperation::getPreValue()

Description.  This method performs identically to getValue(), except that it is used to define a retrieval operation of an attribute's previous value rather than the current value. See Section 2.3.21.13, “NdbEventOperation::getValue()”, for details.

Signature. 

NdbRecAttr* getPreValue
    (
      const char* name,
      char*       value = 0
    )

Parameters.  This method takes the two parameters listed here:

  • The name of the attribute (as a constant character pointer).

  • A pointer to a value, such that:

    • If the attribute value is not NULL, then the attribute value is returned in this parameter.

    • If the attribute value is NULL, then the attribute value is stored only in the NdbRecAttr object returned by this method.

    See value Buffer Memory Allocation, for more information regarding this parameter.

Return value.  An NdbRecAttr object to hold the value of the attribute, or a NULL pointer indicating that an error has occurred.


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