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CDaoWorkspace::CompactDatabase

  • 项目

Call this member function to compact a specified Microsoft Jet (.MDB) database.

static void PASCAL CompactDatabase( 
   LPCTSTR lpszSrcName, 
   LPCTSTR lpszDestName, 
   LPCTSTR lpszLocale = dbLangGeneral, 
   int nOptions = 0  
); 
static void PASCAL CompactDatabase( 
   LPCTSTR lpszSrcName, 
   LPCTSTR lpszDestName, 
   LPCTSTR lpszLocale, 
   int nOptions, 
   LPCTSTR lpszPassword  
);

Parameters

  • lpszSrcName
    The name of an existing, closed database. It can be a full path and filename, such as "C:\\MYDB.MDB". If the filename has an extension, you must specify it. If your network supports the uniform naming convention (UNC), you can also specify a network path, such as "\\\\MYSERVER\\MYSHARE\\MYDIR\\MYDB.MDB". (Double backslashes are required in the path strings because "\" is the C++ escape character.)

  • lpszDestName
    The full path of the compacted database that you are creating. You can also specify a network path as with lpszSrcName. You cannot use the lpszDestName argument to specify the same database file as lpszSrcName.

  • lpszPassword
    A password, used when you want to compact a password-protected database. Note that if you use the version of CompactDatabase that takes a password, you must supply all parameters. Also, because this is a connect parameter, it requires special formatting, as follows: ;PWD=lpszPassword. For example: ;PWD="Happy". (The leading semicolon is required.)

  • lpszLocale
    A string expression used to specify collating order for creating lpszDestName. If you omit this argument by accepting the default value of dbLangGeneral (see below), the locale of the new database is the same as that of the old database. Possible values are:

    • dbLangGeneral   English, German, French, Portuguese, Italian, and Modern Spanish

    • dbLangArabic   Arabic

    • dbLangCyrillic   Russian

    • dbLangCzech   Czech

    • dbLangDutch   Dutch

    • dbLangGreek   Greek

    • dbLangHebrew   Hebrew

    • dbLangHungarian   Hungarian

    • dbLangIcelandic   Icelandic

    • dbLangNordic   Nordic languages (Microsoft Jet database engine version 1.0 only)

    • dbLangNorwdan   Norwegian and Danish

    • dbLangPolish   Polish

    • dbLangSpanish   Traditional Spanish

    • dbLangSwedfin   Swedish and Finnish

    • dbLangTurkish   Turkish

  • nOptions
    Indicates one or more options for the target database, lpszDestName. If you omit this argument by accepting the default value, the lpszDestName will have the same encryption and the same version as lpszSrcName. You can combine the dbEncrypt or dbDecrypt option with one of the version options using the bitwise-OR operator. Possible values, which specify a database format, not a database engine version, are:

    • dbEncrypt   Encrypt the database while compacting.

    • dbDecrypt   Decrypt the database while compacting.

    • dbVersion10   Create a database that uses the Microsoft Jet database engine version 1.0 while compacting.

    • dbVersion11   Create a database that uses the Microsoft Jet database engine version 1.1 while compacting.

    • dbVersion20   Create a database that uses the Microsoft Jet database engine version 2.0 while compacting.

    • dbVersion30   Create a database that uses the Microsoft Jet database engine version 3.0 while compacting.

    You can use dbEncrypt or dbDecrypt in the options argument to specify whether to encrypt or to decrypt the database as it is compacted. If you omit an encryption constant or if you include both dbDecrypt and dbEncrypt, lpszDestName will have the same encryption as lpszSrcName. You can use one of the version constants in the options argument to specify the version of the data format for the compacted database. This constant affects only the version of the data format of lpszDestName. You can specify only one version constant. If you omit a version constant, lpszDestName will have the same version as lpszSrcName. You can compact lpszDestName only to a version that is the same or later than that of lpszSrcName.

    Warning

    If a database is not encrypted, it is possible, even if you implement user/password security, to directly read the binary disk file that constitutes the database.

Remarks

As you change data in a database, the database file can become fragmented and use more disk space than necessary. Periodically, you should compact your database to defragment the database file. The compacted database is usually smaller. You can also choose to change the collating order, the encryption, or the version of the data format while you copy and compact the database.

Warning

The CompactDatabase member function will not correctly convert a complete Microsoft Access database from one version to another. Only the data format is converted. Microsoft Access-defined objects, such as forms and reports, are not converted. However, the data is correctly converted.

Tip

You can also use CompactDatabase to copy a database file.

For more information about compacting databases, see the topic "CompactDatabase Method" in DAO Help.

Requirements

Header: afxdao.h

See Also

Reference

CDaoWorkspace Class

Hierarchy Chart

CDaoWorkspace::RepairDatabase