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CeReadRecordProps (CEDB) (Windows Embedded CE 6.0)

  • Статья

1/6/2010

This function reads properties from the current record. This function is obsolete. Call the CeReadRecordPropsEx (CEDB) function instead.

A RAPI version of this function exists called CeReadRecordPropsEx (RAPI).

Syntax

CEOID CeReadRecordProps(
  HANDLE hDbase, 
  DWORD dwFlags, 
  LPWORD lpcPropID, 
  CEPROPID* rgPropID, 
  LPBYTE* lplpBuffer, 
  LPDWORD lpcbBuffer
);

Parameters

  • hDbase
    [in] Handle to an open database. The database must have been opened by a previous call to the CeOpenDatabaseEx2 (CEDB) function.

  • dwFlags
    [in] Bitmask of read flags. The following table shows possible values.

    Value Description

    CEDB_ALLOWREALLOC

    Indicates that the LocalAlloc function was used to allocate the buffer specified by the lplpBuffer parameter, and the server can reallocate the buffer if it is not large enough to hold the requested properties.
  • lpcPropID
    [in] Pointer to the number of property identifiers in the array specified by the rgPropID parameter. If rgPropID is set to NULL, this parameter receives the number of properties retrieved.
  • rgPropID
    [in] Pointer to an array of property identifiers for the properties to be retrieved. If this parameter is set to NULL, this function retrieves all properties in the record.
  • lplpBuffer
    [out] Pointer to a long pointer to a buffer that receives the requested properties. If the dwFlags parameter includes the CEDB_ALLOWREALLOC flag, the buffer can be reallocated if necessary. If the CEDB_ALLOWREALLOC flag is specified and the content of this parameter is set to NULL, the server uses the LocalAlloc function to allocate a buffer of the appropriate size in the caller's address space and returns a pointer to the buffer. If the CEDB_ALLOWREALLOC flag is specified, it is possible for the value of this pointer to change even on failure. For example, the old memory might be freed, and the allocation might then fail, leaving the pointer set to NULL.
  • lpcbBuffer
    [out] Pointer to a variable that contains the size, in bytes, of the buffer specified by the lplpBuffer parameter. When this function returns, this parameter receives a value that indicates the actual size of the data copied to the buffer. If the buffer was too small to contain the data, this parameter can be used to calculate the amount of memory to allocate for the buffer if CEDB_ALLOWREALLOC was not specified.

Return Value

The object identifier of the record from which the function read indicates success. Zero indicates failure. To get extended error information, call GetLastError. The following table shows possible values.

Value Description

ERROR_INSUFFICIENT_BUFFER

Indicates that the specified buffer was not large enough, and the reallocation failed. If the CEDB_ALLOWREALLOC flag was specified. The lpcbBuffer parameter contains the required buffer size.

ERROR_INVALID_PARAMETER

Indicates that a parameter was invalid.

ERROR_KEY_DELETED

Indicates that the record that was about to be read was deleted by another thread. If the current record was reached as a result of an autoseek, this error is not returned, and the next record is returned.

ERROR_NO_DATA

Indicates that none of the requested properties was found. The output buffer and the size are valid.

ERROR_NO_MORE_ITEMS

Indicates that the current seek pointer is at the end of the database.

Remarks

This function reads the specified set of properties from the current record. If the database was opened with the autoseek flag, that is, if the dwFlags parameter of CeOpenDatabaseEx2 was set to CEDB_AUTOINCREMENT, this function increments the seek pointer so that the next call reads the next record in the current sort order. That is, if the database was opened with a sort order active, this function returns the records in sorted order. If the database was not opened with a sort order active, the order in which records are returned is not predictable.

When rgPropID is set to NULL, this function does not return properties in any specific order. When you set rgPropID to NULL, use a loop to read the properties returned by this function and verify the PropID value of each property, rather than assuming a specific order.

When rgPropID is set to non-NULL, the properties are returned in the order they are listed in rgPropID. If a requested property is not present in the record, the wFlags member of the CEPROPVAL structure is set to CEDB_PROPNOTFOUND.

Read all needed properties from the record in a single call. The entire record is stored in a compressed format, and each time a property is read, it must be decompressed. All the properties are returned in a single marshaled structure, which consists of an array of CEPROPVAL structures, one for each property requested, or one for each property found if the application set rgPropID to NULL when calling this function.

If a variable-sized property was requested, such as strings or BLOBs that are packed in at the end of the array, the pointers in the CEPROPVAL structures point into this marshaled structure. This means that the only memory that must be freed is the original pointer to the buffer passed in to the call. Even if this function fails, it may have allocated memory on the caller's behalf. Free the pointer returned by this function if the pointer is not set to NULL.

Requirements

Header windbase.h
Library coredll.lib
Windows Embedded CE Windows CE 2.10 and later

See Also

Reference

CEDB Functions
CeOpenDatabaseEx2 (CEDB)
CeReadRecordPropsEx (CEDB)
CeSeekDatabaseEx (CEDB)
CEPROPVAL (CEDB)

Other Resources

LocalAlloc
LocalFree