怎样用ADO打开一个带密码的Access库？

韩冰

<>  </P>
; F$ V- _. o6 k3 I5 G7 d8 c<>Creates a new Recordset object and appends it to the Recordsets collection. </P>
0 {6 D4 ~/ N* `& O4 j<>  </P>
<>Syntax </P>
<>  </P>
<>For Connection and Database objects: </P>
<>  </P>
<>Set recordset = object.OpenRecordset (source, type, options, lockedits) </P>
<>  </P>
<>For QueryDef, Recordset, and TableDef objects: </P>
% S4 b$ t$ M6 U9 P# Q$ w5 M& C6 f" Z1 m( M<>  </P>
<>Set recordset = object.OpenRecordset (type, options, lockedits) </P>
<>  </P>
0 _/ R5 U, v* F, ?; l<>The OpenRecordset method syntax has these parts. </P>
) k+ k8 o8 p/ Q2 J% ^1 A  H+ u8 Z2 h<>  </P>
8 R+ j7 }) g8 u, s<>art    Description </P>
<>recordset       An object variable that represents the Recordset object you wantt to </P>
<>open. </P>
6 h6 Y( E$ ~+ i. J<>object  An object variable that represents an existing object from which you </P>
<>want to create the new Recordset. </P>
- d' q5 J/ W* ]2 e. o* {<>source  A String specifying the source of the records for the new Recordset. </P>
7 ]8 D" R  H, g  n; k; n4 I<>The source can be a table name, a query name, or an SQL statement that </P>
+ X! ?& r# S& ^" {+ E( c; s<>returns records. For table-type Recordset objects in Microsoft Jet databases, </P>
8 ^5 r) z$ \; _+ P<>the source can only be a table name. </P>
<>type    Optional. A constant that indicates the type of Recordset to open, as </P>
9 V- T6 Y+ j/ O( i. z* S" _% q7 n<>specified in Settings. </P>
<>options Optional. A combination of constants that specify characteristics of </P>
, M/ {& ^: A2 |% w* R; L. m<>the new Recordset, as listed in Settings. </P>
1 g8 h! V2 M4 L$ A) O0 m<>lockedits       Optional. A constant that determines the locking for the Recordsset, </P>
+ A# Y: e/ g6 ]' l4 i<P>as specified in Settings. </P>
<P>Settings </P>
; D' R, M+ _) s. x2 r3 Z$ z6 N<P>  </P>
<P>You can use one of the following constants for the type argument. </P>
<P>  </P>
' K* J+ M. @& i6 p/ c<P>Constant        Description </P>
<P>  </P>
<P>  </P>
<P>dbOpenTable     Opens a table-type Recordset object (Microsoft Jet workspaces </P>
1 D$ J" U4 q4 [8 L<P>only). </P>
<P>dbOpenDynamic   Opens a dynamic-type Recordset object, which is similar to an </P>
<P>ODBC dynamic cursor. (ODBCDirect workspaces only) </P>
5 _3 U' ?2 H5 J, a% F8 A, Z<P>dbOpenDynaset   Opens a dynaset-type Recordset object, which is similar to an </P>
' R: V$ D' B- C+ ^% l<P>ODBC keyset cursor. </P>
* D  y$ ^  E9 j/ Z2 K# }1 D- N<P>dbOpenSnapshot  Opens a snapshot-type Recordset object, which is similar to an </P>
<P>ODBC static cursor. </P>
<P>dbOpenForwardOnly?Opens a forward-only-type Recordset object. </P>
! o0 S. n2 B# w# V5 U<P>Note   If you open a Recordset in a Microsoft Jet workspace and you don't </P>
* V# q7 R. }, y+ P7 G2 v<P>specify a type, OpenRecordset creates a table-type Recordset, if possible. If </P>
% |2 d! _6 |/ c- _$ f' C<P>you specify a linked table or query, OpenRecordset creates a dynaset-type </P>
<P>Recordset. In an ODBCDirect workspace, the default setting is dbOpenForwardOnl </P>
$ i' l( ?7 P7 A; _* n8 O<P>y. </P>
9 E) c$ z# r% m- {<P>  </P>
<P>You can use a combination of the following constants for the options </P>
<P>argument. </P>
<P>  </P>
<P>Constant        Description </P>
<P>dbAppendOnly?Allows users to append new records to the Recordset, but </P>
; e& K9 q: B5 U<P>prevents them from editing or deleting existing records (Microsoft Jet </P>
9 l4 u6 L( L* p3 W3 V+ ]<P>dynaset-type Recordset only). </P>
<P>dbSQLPassThrough?Passes an SQL statement to a Microsoft Jet-connected ODBC </P>
, r; h& Z4 \7 V8 h6 {<P>data source for processing (Microsoft Jet snapshot-type Recordset only). </P>
<P>dbSeeChanges    Generates a run-time error if one user is changing data that </P>
' R; @& G- c2 H: R; E1 t<P>another user is editing (Microsoft Jet dynaset-type Recordset only). This is </P>
<P>useful in applications where multiple users have simultaneous read/write </P>
6 K4 W: u" t7 c3 [! T+ l<P>access to the same data. </P>
<P>dbDenyWrite?Prevents other users from modifying or adding records (Microsoft </P>
<P>Jet Recordset objects only). </P>
<P>dbDenyRead?Prevents other users from reading data in a table (Microsoft Jet </P>
<P>table-type Recordset only). </P>
<P>dbForwardOnly?Creates a forward-only Recordset (Microsoft Jet snapshot-type </P>
; A4 ], k# ^+ ]' e1 @<P>Recordset only). It is provided only for backward compatibility, and you </P>
<P>should use the dbOpenForwardOnly constant in the type argument instead of </P>
<P>using this option. </P>
7 U0 W, v  l* d% p0 b: d<P>dbReadOnly?Prevents users from making changes to the Recordset (Microsoft Jet </P>
; H9 H& V  E$ H# ]! X2 v7 B  |0 [. z<P>only). The dbReadOnly constant in the lockedits argument replaces this </P>
<P>option, which is provided only for backward compatibility. </P>
) _/ f0 r) y% ~4 K8 Q; b8 C<P>dbRunAsync      Runs an asynchronous query (ODBCDirect workspaces only). </P>
<P>dbExecDirect?Runs a query by skipping SQLPrepare and directly calling </P>
<P>SQLExecDirect (ODBCDirect workspaces only). Use this option only when you抮e </P>
- U6 o; {! x4 _7 b  z<P>not opening a Recordset based on a parameter query. For more information, see </P>
# G! s8 c7 W. V7 ^4 _, c( O" L<P>the "Microsoft ODBC 3.0 Programmer抯 Reference." </P>
<P>dbInconsistent?Allows inconsistent updates (Microsoft Jet dynaset-type and </P>
9 q. z8 V7 A. y& {0 l: Y<P>snapshot-type Recordset objects only). </P>
( i& U- S6 S8 \0 t<P>dbConsistent?Allows only consistent updates (Microsoft Jet dynaset-type and </P>
+ x  {2 V! U, e( u<P>snapshot-type Recordset objects only). </P>
<P>Note   The constants dbConsistent and dbInconsistent are mutually exclusive, </P>
" r0 \! ^* L) _! O+ n; t<P>and using both causes an error. Supplying a lockedits argument when options </P>
; t+ h2 b9 M# h' _) x" d0 D<P>uses the dbReadOnly constant also causes an error. </P>
/ L- _) H. i' v: ]& D6 r( c<P>  </P>
6 r( d* _8 v5 G& l2 j<P>You can use the following constants for the lockedits argument. </P>
( n# {6 |# s4 v7 F" D<P>  </P>
2 @3 b+ c: W% P0 `, i  C3 E<P>Constant        Description </P>
<P>dbReadOnly      Prevents users from making changes to the Recordset (default for </P>
+ b* ]5 S" t0 s$ X/ N( O<P>ODBCDirect workspaces). You can use dbReadOnly in either the options argument </P>
0 n; w+ T, _( w0 J0 c$ H<P>or the lockedits argument, but not both. If you use it for both arguments, a </P>
<P>run-time error occurs. </P>
<P>dbPessimistic?Uses pessimistic locking to determine how changes are made to </P>
- f8 r& h) x7 P5 m<P>the Recordset in a multiuser environment. The page containing the record </P>
& W5 X) G; H# j$ U( ~' x; d# F; |) L( y<P>you're editing is locked as soon as you use the Edit method (default for </P>
8 a7 p  m. X! A# U/ T; v<P>Microsoft Jet workspaces). </P>
<P>dbOptimistic?Uses optimistic locking to determine how changes are made to the </P>
2 a/ o1 a: H2 H$ L5 z# @/ f6 @- r<P>Recordset in a multiuser environment. The page containing the record is not </P>
<P>locked until the Update method is executed. </P>
<P>dbOptimisticValue?Uses optimistic concurrency based on row values (ODBCDirect </P>
' O) b2 I# }! E* `2 V9 u<P>workspaces only). </P>
9 o& e5 \/ j8 g8 u9 I& U7 v<P>dbOptimisticBatch?Enables batch optimistic updating (ODBCDirect workspaces </P>
* z6 N/ G' t) w5 r, H  U+ ~<P>only). </P>
* O4 C6 R0 ^5 ?8 r1 B1 O<P>Remarks </P>
* w! @! W: x. Y8 T! b5 a<P>  </P>
<P>In a Microsoft Jet workspace, if object refers to a QueryDef object, or a </P>
+ |0 e3 M8 [# a2 w! f$ N/ G# ?<P>dynaset- or snapshot-type Recordset, or if source refers to an SQL statement </P>
<P>or a TableDef that represents a linked table, you can't use dbOpenTable for </P>
( y$ R+ B+ T6 g, P2 y<P>the type argument; if you do, a run-time error occurs. If you want to use an </P>
<P>SQL pass-through query on a linked table in a Microsoft Jet-connected ODBC </P>
<P>data source, you must first set the Connect property of the linked table's </P>
<P>database to a valid ODBC connection string. If you only need to make a single </P>
<P>pass through a Recordset opened from a Microsoft Jet-connected ODBC data </P>
4 `$ P. n9 I3 x4 d) d/ `9 T9 U<P>source, you can improve performance by using dbOpenForwardOnly for the type </P>
<P>argument. </P>
: n  j8 Q% R1 a) w' C4 d! b<P>  </P>
<P>If object refers to a dynaset- or snapshot-type Recordset, the new Recordset </P>
<P>is of the same type object. If object </P>
' y: X9 i- H0 t<P> refers to a table-type Recordset object, the type of the new object is a </P>
<P>dynaset-type Recordset. You can't open new Recordset objects from forward-only </P>
<P>杢ype or ODBCDirect Recordset objects. </P>
- w" [( ~! _) j2 `! t<P>In an ODBCDirect workspace, you can open a Recordset containing more than one </P>
, T+ X! h4 L* {3 `) \<P>select query in the source argument, such as </P>
8 o1 D% Y0 s/ {) v  I+ @( X<P>  </P>
* b# [- A  e! M  Y0 e# L<P>"SELECT LastName, FirstName FROM Authors </P>
<P>WHERE LastName = 'Smith'; </P>
<P>SELECT Title, ISBN FROM Titles </P>
7 `# {; s8 k; ]6 M<P>WHERE ISBN Like '1-55615-*'" </P>
- C/ z- e9 D+ T  N2 }<P>  </P>
<P>The returned Recordset will open with the results of the first query. To </P>
<P>obtain the result sets of records from subsequent queries, use the </P>
: B( G9 N# U* i  s) Q5 l<P>NextRecordset method. </P>
4 t! k3 O; M% E, P5 Y# a3 D<P>  </P>
. q2 \% }2 q9 B; C2 I6 k<P>Note   You can send DAO queries to a variety of different database servers </P>
<P>with ODBCDirect, and different servers will recognize slightly different </P>
  m, ]5 z6 B2 t! \: u/ L<P>dialects of SQL. Therefore, context-sensitive Help is no longer provided for </P>
<P>Microsoft Jet SQL, although online Help for Microsoft Jet SQL is still </P>
<P>included through the Help menu. Be sure to check the appropriate reference </P>
8 b) k' @* Y! R& Q<P>documentation for the SQL dialect of your database server when using either </P>
+ x0 V; O: A. `: M( Q( i2 U; y<P>ODBCDirect connections or pass-through queries in Microsoft Jet-connected </P>
<P>client/server applications. </P>
/ {+ `) I* i4 ?* W$ X% n<P>  </P>
' G% [7 T  G! x' L/ ^2 m<P>Use the dbSeeChanges constant in a Microsoft Jet workspace if you want to </P>
<P>trap changes while two or more users are editing or deleting the same record. </P>
<P>For example, if two users start editing the same record, the first user to </P>
<P>execute the Update method succeeds. When the second user invokes the Update </P>
8 K9 J& x  h5 ?( `0 k/ u, Y8 c6 @5 N<P>method, a run-time error occurs. Similarly, if the second user tries to use </P>
# f2 m+ R0 I) L2 P1 \$ V2 y) X<P>the Delete method to delete the record, and the first user has already </P>
<P>changed it, a run-time error occurs. </P>
; S0 x  k6 g6 u0 s" ?5 B4 Z<P>  </P>
<P>Typically, if the user gets this error while updating a record, your code </P>
3 p7 ]' P$ f/ c  r) I+ y<P>should refresh the contents of the fields and retrieve the newly modified </P>
: z- ?' G: w1 m- T& y<P>values. If the error occurs while deleting a record, your code could display </P>
0 B2 j. p( Q) a) R6 y# S) C; N' G<P>the new record data to the user and a message indicating that the data has </P>
0 G. n% T+ s& q! ~# k<P>recently changed. At this point, your code can request a confirmation that </P>
" t5 Q3 L  ~. `/ j! |6 j2 f- i<P>the user still wants to delete the record. </P>
, @% U8 `" E* h8 @/ V* e<P>  </P>
<P>You should also use the dbSeeChanges constant if you open a Recordset in a </P>
<P>Microsoft Jet-connected ODBC workspace against a Microsoft SQL Server 6.0 (or </P>
<P>later) table that has an IDENTITY column, otherwise an error may result. </P>
& \2 G. H% Z; f<P>  </P>
<P>In an ODBCDirect workspace, you can execute asynchronous queries by setting </P>
<P>the dbRunAsync constant in the options argument. This allows your application </P>
/ l4 f/ x! g' B+ p4 N  G<P>to continue processing other statements while the query runs in the </P>
* V- J5 ^  w. D<P>background. But, you cannot access the Recordset data until the query has </P>
<P>completed. To determine whether the query has finished executing, check the </P>
<P>StillExecuting property of the new Recordset. If the query takes longer to </P>
<P>complete than you anticipated, you can terminate execution of the query with </P>
<P>the Cancel method. </P>
1 w( ^4 S$ n4 P# G! k/ v/ B7 \9 n<P>  </P>
/ H+ W& c9 D  k<P>Opening more than one Recordset on an ODBC data source may fail because the </P>
<P>connection is busy with a prior </P>
<P>OpenRecordset call. One way around this is to use a server-side cursor and </P>
<P>ODBCDirect, if the server supports this. Another solution is to fully </P>
/ }5 K5 p1 N/ C, F* c' I<P>populate the Recordset by using the MoveLast method as soon as the Recordset </P>
<P>is opened. </P>
7 K, o/ B; c$ Z- T# O4 x' ?<P>  </P>
8 l6 S2 f% t. I% _2 |3 ~9 n7 _<P>If you open a Connection object with DefaultCursorDriver set to </P>
<P>dbUseClientBatchCursor, you can open a Recordset to cache changes to the data </P>
<P>(known as batch updating) in an ODBCDirect workspace. Include dbOptimisticBatc </P>
<P>h in the lockedits argument to enable update caching. See the Update method </P>
<P>topic for details about how to write changes to disk immediately, or to cache </P>
" p9 }( m' k; D6 h0 l<P>changes and write them to disk as a batch. </P>
<P>  </P>
<P>Closing a Recordset with the Close method automatically deletes it from the </P>
, n  |. i0 T' R+ g3 D" f: p
<P>Recordsets collection. </P>
<P>  </P>
<P>Note   If source refers to an SQL statement composed of a string concatenated </P>
<P>with a non-integer value, and the system parameters specify a non-U.S. </P>
<P>decimal character such as a comma (for example, strSQL = "PRICE &gt; " &amp; </P>
<P>lngPrice, and lngPrice = 125,50), an error occurs when you try to open the </P>
) H( Y  J3 J9 a" y+ c2 h* M$ a$ \<P>Recordset. This is because during concatenation, the number will be converted </P>
3 |& E7 u; g% [5 _& Q5 z# C<P>to a string using your system's default decimal character, and SQL only </P>
<P>accepts U.S. decimal characters.</P>