下列常量由此扩展定义,且仅在此扩展编译入 PHP 或在运行时动态载入时可用。
DBX_MYSQL 
      (integer)
     DBX_ODBC 
      (integer)
     DBX_PGSQL 
      (integer)
     DBX_MSSQL 
      (integer)
     DBX_FBSQL 
      (integer)
     DBX_OCI8 
      (integer) (available from PHP 4.3.0)
     DBX_SYBASECT 
      (integer)
     DBX_SQLITE 
      (integer) (PHP 5)
     DBX_PERSISTENT 
      (integer)
     DBX_RESULT_INFO 
      (integer)
     DBX_RESULT_INDEX 
      (integer)
     DBX_RESULT_ASSOC 
      (integer)
     DBX_RESULT_UNBUFFERED 
      (integer) (PHP 5)
     DBX_COLNAMES_UNCHANGED 
      (integer) (available from PHP 4.3.0)
     DBX_COLNAMES_UPPERCASE 
      (integer) (available from PHP 4.3.0)
     DBX_COLNAMES_LOWERCASE 
      (integer) (available from PHP 4.3.0)
     DBX_CMP_NATIVE 
      (integer)
     DBX_CMP_TEXT 
      (integer)
     DBX_CMP_NUMBER 
      (integer)
     DBX_CMP_ASC 
      (integer)
     DBX_CMP_DESC 
      (integer)