怎样用ADO打开一个带密码的Access库？

韩冰

<>  </P>
<>Creates a new Recordset object and appends it to the Recordsets collection. </P>
# P; E. `! {, W2 {) m/ [8 q<>  </P>
1 J% Y& d+ ]! b) e<>Syntax </P>
1 f" G6 M' W! A, R3 Q) |8 w& c<>  </P>
) g3 E- l8 s/ k7 g7 {7 y<>For Connection and Database objects: </P>
& q$ A: W  Q2 }) l$ O<>  </P>
<>Set recordset = object.OpenRecordset (source, type, options, lockedits) </P>
" C7 `- S, s1 m8 }<>  </P>
' z/ U9 h# ~0 |: G<>For QueryDef, Recordset, and TableDef objects: </P>
<>  </P>
<>Set recordset = object.OpenRecordset (type, options, lockedits) </P>
<>  </P>
<>The OpenRecordset method syntax has these parts. </P>
( U& x6 h* }1 L" C  q' s. d4 G! [<>  </P>
/ D1 c( E) E. u' t<>art    Description </P>
9 B0 X+ v7 _, A3 h8 D<>recordset       An object variable that represents the Recordset object you wantt to </P>
<>open. </P>
& D0 F$ O. i/ R  U' n7 q<>object  An object variable that represents an existing object from which you </P>
<>want to create the new Recordset. </P>
<>source  A String specifying the source of the records for the new Recordset. </P>
$ v' q0 ~" I/ ~* c1 d" ^<>The source can be a table name, a query name, or an SQL statement that </P>
<>returns records. For table-type Recordset objects in Microsoft Jet databases, </P>
<>the source can only be a table name. </P>
<>type    Optional. A constant that indicates the type of Recordset to open, as </P>
<>specified in Settings. </P>
7 N# {6 G2 E  d2 b) r<>options Optional. A combination of constants that specify characteristics of </P>
<>the new Recordset, as listed in Settings. </P>
) i9 o: [$ O8 p$ x! Q3 L) p<>lockedits       Optional. A constant that determines the locking for the Recordsset, </P>
6 m7 r0 I* S2 M- M" Z4 A8 J<P>as specified in Settings. </P>
<P>Settings </P>
/ O+ H  @$ {; h5 V. J2 o<P>  </P>
3 S% {8 J8 b; N# Y- p) @% n% v<P>You can use one of the following constants for the type argument. </P>
<P>  </P>
( T3 ~2 x0 K, U+ v% Z  D* e( r<P>Constant        Description </P>
, v$ X6 W9 @  M9 o" f* [% s9 r# M2 @<P>  </P>
<P>  </P>
<P>dbOpenTable     Opens a table-type Recordset object (Microsoft Jet workspaces </P>
; R" W) c  a) A' H  U<P>only). </P>
8 |4 h0 h+ {/ X7 i  g$ \, K/ n<P>dbOpenDynamic   Opens a dynamic-type Recordset object, which is similar to an </P>
<P>ODBC dynamic cursor. (ODBCDirect workspaces only) </P>
<P>dbOpenDynaset   Opens a dynaset-type Recordset object, which is similar to an </P>
* G* y5 d6 m' S: g<P>ODBC keyset cursor. </P>
6 q; A4 ]( e' E7 v( w# i$ f5 y<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>
, P, T8 [* ~4 P; Y<P>Note   If you open a Recordset in a Microsoft Jet workspace and you don't </P>
1 V% h! i! C: \- C<P>specify a type, OpenRecordset creates a table-type Recordset, if possible. If </P>
9 W' D8 y3 W3 y& `5 m& G0 I- g: t8 \6 F<P>you specify a linked table or query, OpenRecordset creates a dynaset-type </P>
3 }( Q# }+ @0 N<P>Recordset. In an ODBCDirect workspace, the default setting is dbOpenForwardOnl </P>
$ g+ B0 {* W0 ~, w/ m<P>y. </P>
  M/ Y: M; y: Q+ P0 R<P>  </P>
<P>You can use a combination of the following constants for the options </P>
<P>argument. </P>
<P>  </P>
' Q+ m1 n' e# f; O& A' t2 r0 k<P>Constant        Description </P>
9 M( n( F) v% ?/ \* B6 B7 W<P>dbAppendOnly?Allows users to append new records to the Recordset, but </P>
5 v/ X2 u$ @+ Z" u/ K# q! r<P>prevents them from editing or deleting existing records (Microsoft Jet </P>
' {! Y" z6 Y) n( Q, I& @<P>dynaset-type Recordset only). </P>
2 z+ Z' r; c* ^8 |1 W<P>dbSQLPassThrough?Passes an SQL statement to a Microsoft Jet-connected ODBC </P>
<P>data source for processing (Microsoft Jet snapshot-type Recordset only). </P>
3 l( O5 u* d& j3 c7 O: L0 a. i<P>dbSeeChanges    Generates a run-time error if one user is changing data that </P>
# C- x3 g+ |' K7 q* T! F8 N<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>
7 @3 ~; e- y8 ~+ Y$ m$ T* E6 n<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>
% H, y2 u) J0 v% |8 W<P>dbDenyRead?Prevents other users from reading data in a table (Microsoft Jet </P>
1 _  x& V! ^$ d* v6 C! x<P>table-type Recordset only). </P>
4 Q& C* R) }: k+ q2 t9 b) p' A; }<P>dbForwardOnly?Creates a forward-only Recordset (Microsoft Jet snapshot-type </P>
# m& N( |+ u8 u% e<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>
6 m/ v) e) N2 n6 g<P>dbReadOnly?Prevents users from making changes to the Recordset (Microsoft Jet </P>
<P>only). The dbReadOnly constant in the lockedits argument replaces this </P>
$ x3 L4 e% n- J0 e) q5 U<P>option, which is provided only for backward compatibility. </P>
<P>dbRunAsync      Runs an asynchronous query (ODBCDirect workspaces only). </P>
- {' N2 @2 {1 I8 Z<P>dbExecDirect?Runs a query by skipping SQLPrepare and directly calling </P>
2 J7 }# p2 o6 h, B! Y<P>SQLExecDirect (ODBCDirect workspaces only). Use this option only when you抮e </P>
" ^5 p' Q" |# v<P>not opening a Recordset based on a parameter query. For more information, see </P>
% ~9 t$ h5 W8 O7 S8 C$ w<P>the "Microsoft ODBC 3.0 Programmer抯 Reference." </P>
<P>dbInconsistent?Allows inconsistent updates (Microsoft Jet dynaset-type and </P>
9 K2 H1 x. u: L2 L" S% L7 g  X" X<P>snapshot-type Recordset objects only). </P>
8 R% y: e: y2 N<P>dbConsistent?Allows only consistent updates (Microsoft Jet dynaset-type and </P>
<P>snapshot-type Recordset objects only). </P>
4 q  f* A# t% H1 q* y) |7 o<P>Note   The constants dbConsistent and dbInconsistent are mutually exclusive, </P>
<P>and using both causes an error. Supplying a lockedits argument when options </P>
3 D7 Y7 J4 J' ~<P>uses the dbReadOnly constant also causes an error. </P>
/ l' i7 X/ Q7 l; Y. j1 X) [3 L<P>  </P>
7 D2 ^2 R, r0 M6 U! `4 d- }<P>You can use the following constants for the lockedits argument. </P>
& |" Y& o4 U" b  r( v<P>  </P>
6 j+ x3 ^$ b5 V, A<P>Constant        Description </P>
9 ~1 z0 w! ?% S* c) }& o) Q  S<P>dbReadOnly      Prevents users from making changes to the Recordset (default for </P>
<P>ODBCDirect workspaces). You can use dbReadOnly in either the options argument </P>
<P>or the lockedits argument, but not both. If you use it for both arguments, a </P>
$ j' r4 {5 Y  k3 b( t<P>run-time error occurs. </P>
<P>dbPessimistic?Uses pessimistic locking to determine how changes are made to </P>
: z6 ^+ k% L5 B: K' h  @<P>the Recordset in a multiuser environment. The page containing the record </P>
' b% R, \0 Y4 }8 w# `) A<P>you're editing is locked as soon as you use the Edit method (default for </P>
<P>Microsoft Jet workspaces). </P>
* I7 B/ H% R  `& @* n<P>dbOptimistic?Uses optimistic locking to determine how changes are made to the </P>
<P>Recordset in a multiuser environment. The page containing the record is not </P>
<P>locked until the Update method is executed. </P>
) G% ]" Q+ ?9 t6 H5 R+ v; A! l<P>dbOptimisticValue?Uses optimistic concurrency based on row values (ODBCDirect </P>
<P>workspaces only). </P>
6 k. L! C7 b6 h<P>dbOptimisticBatch?Enables batch optimistic updating (ODBCDirect workspaces </P>
+ y6 U7 [7 r' _! E<P>only). </P>
<P>Remarks </P>
7 @, g0 k6 B" N7 G" E% Y& n<P>  </P>
<P>In a Microsoft Jet workspace, if object refers to a QueryDef object, or a </P>
<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>
4 C* V2 W+ X; E' q( \<P>the type argument; if you do, a run-time error occurs. If you want to use an </P>
% m5 G4 k0 d" ?8 {8 m5 i<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>
<P>source, you can improve performance by using dbOpenForwardOnly for the type </P>
<P>argument. </P>
& a, p+ K" O) r" X! p$ e<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>
<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>
- R0 m2 I4 Q6 P7 S; R# `<P>杢ype or ODBCDirect Recordset objects. </P>
+ K+ \# B& F4 M; G/ a3 i1 p8 R& n<P>In an ODBCDirect workspace, you can open a Recordset containing more than one </P>
<P>select query in the source argument, such as </P>
1 L" i& k( [; j1 O) q1 T<P>  </P>
<P>"SELECT LastName, FirstName FROM Authors </P>
<P>WHERE LastName = 'Smith'; </P>
9 T1 ?& f# g# l<P>SELECT Title, ISBN FROM Titles </P>
9 E5 _; @- v- \<P>WHERE ISBN Like '1-55615-*'" </P>
<P>  </P>
# k. d" |% y" ?<P>The returned Recordset will open with the results of the first query. To </P>
) |8 ]8 _  o; v: _0 d$ ~5 O4 u<P>obtain the result sets of records from subsequent queries, use the </P>
+ h2 ?- C7 P+ x4 H$ c3 n<P>NextRecordset method. </P>
$ ]4 ^- H7 ^2 Z<P>  </P>
<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>
<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+ A4 L! N6 q0 c/ O* t<P>included through the Help menu. Be sure to check the appropriate reference </P>
<P>documentation for the SQL dialect of your database server when using either </P>
<P>ODBCDirect connections or pass-through queries in Microsoft Jet-connected </P>
<P>client/server applications. </P>
<P>  </P>
<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>
1 y8 F! P$ {5 |7 Q$ Z1 Z<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>
<P>method, a run-time error occurs. Similarly, if the second user tries to use </P>
' S& L$ U9 M% q5 C! I% X" N<P>the Delete method to delete the record, and the first user has already </P>
<P>changed it, a run-time error occurs. </P>
) v( x' j5 o, M<P>  </P>
<P>Typically, if the user gets this error while updating a record, your code </P>
- U2 I/ C9 l* U' k, X' A<P>should refresh the contents of the fields and retrieve the newly modified </P>
" X! ^9 O# C2 e0 T1 N<P>values. If the error occurs while deleting a record, your code could display </P>
<P>the new record data to the user and a message indicating that the data has </P>
) l: r$ |. R% H<P>recently changed. At this point, your code can request a confirmation that </P>
' @* v; K/ g0 @) |: n<P>the user still wants to delete the record. </P>
& I. E; R3 v2 o' e3 g<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>
: T: W+ i# E0 k7 Z- b6 K; q<P>later) table that has an IDENTITY column, otherwise an error may result. </P>
6 Q8 {1 `6 w. [. K- r' t# p<P>  </P>
<P>In an ODBCDirect workspace, you can execute asynchronous queries by setting </P>
. n: g. b) k7 ~5 ?$ v4 I& F) |9 m4 k<P>the dbRunAsync constant in the options argument. This allows your application </P>
<P>to continue processing other statements while the query runs in the </P>
<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>
9 s8 o, `: z/ u. }<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>
5 H6 B" v; X  n) a. f<P>the Cancel method. </P>
4 C  ~% |5 L& X7 a' V<P>  </P>
. b. K# x; K9 C<P>Opening more than one Recordset on an ODBC data source may fail because the </P>
# }9 `* r% B+ t<P>connection is busy with a prior </P>
$ q3 u# A- l/ H' L. J7 m$ R5 L<P>OpenRecordset call. One way around this is to use a server-side cursor and </P>
0 W3 ^! d2 b* y" W3 j! {<P>ODBCDirect, if the server supports this. Another solution is to fully </P>
4 O" ]9 g1 s5 K, f& Y4 a<P>populate the Recordset by using the MoveLast method as soon as the Recordset </P>
5 I6 E: Y- [* Y0 c  g<P>is opened. </P>
7 c5 Y& Y2 W$ D0 r6 t  c) r<P>  </P>
<P>If you open a Connection object with DefaultCursorDriver set to </P>
5 a$ i' ^) d& R0 c<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>
! H) r0 |; j$ J( [7 I<P>topic for details about how to write changes to disk immediately, or to cache </P>
<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>
3 |! a, x* W# i& x" u' K
<P>Recordsets collection. </P>
( O$ E- f. b8 B6 D<P>  </P>
8 ~0 Q, `3 u( ?8 c<P>Note   If source refers to an SQL statement composed of a string concatenated </P>
( Y6 n7 o2 R! s& t: x# J9 }2 J' I8 O. |<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>
<P>Recordset. This is because during concatenation, the number will be converted </P>
<P>to a string using your system's default decimal character, and SQL only </P>
( S0 s/ N6 u5 h<P>accepts U.S. decimal characters.</P>