SysLib.defineDatabaseAlias

系统函数 SysLib.defineDatabaseAlias 创建一个别名,该别名可用来建立与代码已连接至的数据库的新连接。建立连接后,可以下列任何函数中使用该别名:

sysLib.connect 语法图
alias
一个字符串文字或变量,充当第二个参数中标识的连接的别名。别名是不区分大小写的。
database
在 sysLib.connect 或 VGLib.connectionService 中指定的数据库名称。使用字符类型的文字或变量。

如果未指定连接,则函数将影响当前连接。

示例如下所示:
  // Connect to a database with alias "alias", 
  // which becomes the current connection.
  defineDatabaseAlias( "alias", "database" );
  connect( "alias", "user", "pwd" );

  // Make two connections to the same database.
  String db = "database";
  defineDatabaseAlias( "alias1", db );
  defineDatabaseAlias( "alias2", db );
  connect( "alias1", "user", "pwd" );
  connect( "alias2", "user", "pwd" );

  // Another way to make two connections 
  // to the same database.
  defineDatabaseAlias( "alias", "database" );
  connect( "alias", "user", "pwd" );
  connect( "database", "user", "pwd" );

  // An alias is defined but not used. The second 
  // connect() does not create a new connection.
  defineDatabaseAlias( "alias", "database" );
  connect( "database", "user", "pwd" );
  connect( "database", "user", "pwd" );

  // Use of an alias (which is case-insensitive)
  // when disconnecting.   
  defineDatabaseAlias( "alias", "database" );
  connect( "aLiAs", "user", "pwd" );
  disconnect( "ALIAS" );

  // The next disconnect call fails because the 
  // connection is called "alias" not "database".
  defineDatabaseAlias( "alias", "database" );
  connect( "alias", "user", "pwd" );
  disconnect( "database" );

  // An alias may change. After the next call, 
  // "alias" refers to "firstDatabase" 
  defineDatabaseAlias( "alias", "firstDatabase" );

  // After  the next call, 
  // "alias" refers to "secondDatabase".  
  defineDatabaseAlias( "alias", "secondDatabase" );

  // The last call would have failed 
  // if a connection was in place with "alias".

相关概念
SQL 支持

相关参考
SysLib.beginDatabaseTransactionsysLib.connect
sysLib.disconnect
sysLib.setCurrentDatabase
VGLib.connectionService

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