怎样用ADO打开一个带密码的Access库？

韩冰

<>  </P>
4 L8 T2 g" k3 b* t' }* V<>Creates a new Recordset object and appends it to the Recordsets collection. </P>
<>  </P>
<>Syntax </P>
<>  </P>
<>For Connection and Database objects: </P>
<>  </P>
<>Set recordset = object.OpenRecordset (source, type, options, lockedits) </P>
<>  </P>
+ T9 w; a# [+ ]/ Y! {8 o6 c<>For QueryDef, Recordset, and TableDef objects: </P>
<>  </P>
<>Set recordset = object.OpenRecordset (type, options, lockedits) </P>
4 c1 d! G2 f( c9 `5 x3 L+ G<>  </P>
* }( s$ E2 e; y<>The OpenRecordset method syntax has these parts. </P>
<>  </P>
2 T1 h! W+ h1 g+ j<>art    Description </P>
<>recordset       An object variable that represents the Recordset object you wantt to </P>
<>open. </P>
7 T; |1 e9 y4 P3 t% ^% c<>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>
% y! T1 Z1 k/ f, V8 A<>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>
# u: n2 S5 {% R3 E, J: q7 L<>the source can only be a table name. </P>
; ~1 y9 m/ a! f$ d<>type    Optional. A constant that indicates the type of Recordset to open, as </P>
<>specified in Settings. </P>
<>options Optional. A combination of constants that specify characteristics of </P>
<>the new Recordset, as listed in Settings. </P>
<>lockedits       Optional. A constant that determines the locking for the Recordsset, </P>
<P>as specified in Settings. </P>
1 h# e  O- g: O6 o" X1 C<P>Settings </P>
  }9 N+ s4 t% U+ X/ G<P>  </P>
<P>You can use one of the following constants for the type argument. </P>
2 a8 B5 {; I3 i# w& Q<P>  </P>
<P>Constant        Description </P>
0 N* P2 Z9 L) `( {<P>  </P>
1 i5 z6 u$ h& I% G$ ~4 g<P>  </P>
<P>dbOpenTable     Opens a table-type Recordset object (Microsoft Jet workspaces </P>
: T( ]0 |! ]4 u) M3 E6 z! V<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>
6 Z) X0 v- m) b: ~<P>dbOpenDynaset   Opens a dynaset-type Recordset object, which is similar to an </P>
<P>ODBC keyset cursor. </P>
; d* P% {4 x  s<P>dbOpenSnapshot  Opens a snapshot-type Recordset object, which is similar to an </P>
7 A5 M3 L4 `( n& s5 o* B% R<P>ODBC static cursor. </P>
/ }% T( a4 Q3 E$ u7 Q  y7 e<P>dbOpenForwardOnly?Opens a forward-only-type Recordset object. </P>
5 R! K4 C: x' s) w2 u<P>Note   If you open a Recordset in a Microsoft Jet workspace and you don't </P>
<P>specify a type, OpenRecordset creates a table-type Recordset, if possible. If </P>
<P>you specify a linked table or query, OpenRecordset creates a dynaset-type </P>
4 Z8 Z' S( F. R7 ]6 |+ M<P>Recordset. In an ODBCDirect workspace, the default setting is dbOpenForwardOnl </P>
<P>y. </P>
<P>  </P>
<P>You can use a combination of the following constants for the options </P>
! A& k$ b. \; X4 ^<P>argument. </P>
  F) v1 `9 X9 p4 V( T, T- o<P>  </P>
<P>Constant        Description </P>
+ f8 n( K, P& G/ `1 t/ D  \+ W<P>dbAppendOnly?Allows users to append new records to the Recordset, but </P>
<P>prevents them from editing or deleting existing records (Microsoft Jet </P>
<P>dynaset-type Recordset only). </P>
9 R+ R9 W( D' S# s+ p<P>dbSQLPassThrough?Passes an SQL statement to a Microsoft Jet-connected ODBC </P>
$ _; E. O& P/ y" x7 ^<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>
<P>another user is editing (Microsoft Jet dynaset-type Recordset only). This is </P>
% q. `7 F3 {4 y  z/ X, n<P>useful in applications where multiple users have simultaneous read/write </P>
/ W4 t4 P8 c$ w, j; B<P>access to the same data. </P>
9 v! H* @! D$ k8 v6 R' l9 e+ W4 F" F<P>dbDenyWrite?Prevents other users from modifying or adding records (Microsoft </P>
. H; @9 _9 n" S) r% b<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>
2 ?- R; R* f! h2 L<P>dbForwardOnly?Creates a forward-only Recordset (Microsoft Jet snapshot-type </P>
) m! I2 q1 }9 H4 e9 Z! o; \<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>
$ \0 f' [( x9 N* }6 t$ `# `9 B<P>using this option. </P>
/ B6 V2 P/ ^# O# n<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>
" h! O- [) ?2 p/ p% l( H$ ^) G<P>option, which is provided only for backward compatibility. </P>
# ?" P1 H% d. D& K; Z<P>dbRunAsync      Runs an asynchronous query (ODBCDirect workspaces only). </P>
. J5 ~# m) }5 ^& {" [7 v<P>dbExecDirect?Runs a query by skipping SQLPrepare and directly calling </P>
9 ^7 ?+ F! v7 M6 I) [3 j<P>SQLExecDirect (ODBCDirect workspaces only). Use this option only when you抮e </P>
9 Y" I( n7 b* `+ F# Y8 ~<P>not opening a Recordset based on a parameter query. For more information, see </P>
8 r6 Q5 f/ Y8 {; |: d, [- a0 U; f<P>the "Microsoft ODBC 3.0 Programmer抯 Reference." </P>
! A8 j5 `$ r6 _<P>dbInconsistent?Allows inconsistent updates (Microsoft Jet dynaset-type and </P>
) `) m7 Y5 z& }% s, z. u<P>snapshot-type Recordset objects only). </P>
<P>dbConsistent?Allows only consistent updates (Microsoft Jet dynaset-type and </P>
9 U+ X- B6 s' ~: p# J<P>snapshot-type Recordset objects only). </P>
$ B$ o8 r2 `: O* e1 ]/ j) P<P>Note   The constants dbConsistent and dbInconsistent are mutually exclusive, </P>
8 p' X: K7 p8 d* [<P>and using both causes an error. Supplying a lockedits argument when options </P>
<P>uses the dbReadOnly constant also causes an error. </P>
/ g3 @3 `) |* D: F<P>  </P>
<P>You can use the following constants for the lockedits argument. </P>
& z5 t8 w8 k* A<P>  </P>
, F- W4 d% e& ?$ B% Q5 O9 X<P>Constant        Description </P>
<P>dbReadOnly      Prevents users from making changes to the Recordset (default for </P>
- L6 E: y9 l2 N; E; s  e<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>
& u' X( g/ o9 @% U<P>run-time error occurs. </P>
2 K5 P, d* n8 ^/ Z6 R+ w; K<P>dbPessimistic?Uses pessimistic locking to determine how changes are made to </P>
3 e) y9 u- w* {$ P) ^<P>the Recordset in a multiuser environment. The page containing the record </P>
0 }, A# Y; Z9 B# `- W) S% G( h) |<P>you're editing is locked as soon as you use the Edit method (default for </P>
<P>Microsoft Jet workspaces). </P>
<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>
( V4 w& h5 K  u2 P( ^<P>dbOptimisticValue?Uses optimistic concurrency based on row values (ODBCDirect </P>
2 F8 T' m3 ~  T  x<P>workspaces only). </P>
<P>dbOptimisticBatch?Enables batch optimistic updating (ODBCDirect workspaces </P>
6 D$ b, d5 u8 _  D6 O' A2 B<P>only). </P>
<P>Remarks </P>
<P>  </P>
<P>In a Microsoft Jet workspace, if object refers to a QueryDef object, or a </P>
5 ?' B( r3 q" [* h& t<P>dynaset- or snapshot-type Recordset, or if source refers to an SQL statement </P>
# d9 U! X" O2 g2 `- s3 H: R8 a$ H<P>or a TableDef that represents a linked table, you can't use dbOpenTable for </P>
<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>
0 s  C9 t. V8 c! G<P>data source, you must first set the Connect property of the linked table's </P>
& e& g0 R6 t, P& S<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>
1 T5 C5 Y8 l7 N- s<P>source, you can improve performance by using dbOpenForwardOnly for the type </P>
2 j  K4 {* L* F/ x; x! Y7 b% k<P>argument. </P>
<P>  </P>
' Q1 ^1 h" i9 F/ j. y( g5 n<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>
7 p8 O. |. U9 w4 l6 K  @<P>杢ype or ODBCDirect Recordset objects. </P>
<P>In an ODBCDirect workspace, you can open a Recordset containing more than one </P>
0 \* H% `- }& e* l' V% b  c<P>select query in the source argument, such as </P>
, {" k, _2 S( E" g- B- I& n<P>  </P>
<P>"SELECT LastName, FirstName FROM Authors </P>
( I* w; b& V& n% Y<P>WHERE LastName = 'Smith'; </P>
<P>SELECT Title, ISBN FROM Titles </P>
* J! u1 _) O' ]/ ^<P>WHERE ISBN Like '1-55615-*'" </P>
<P>  </P>
3 b; V& a' j1 V* }7 q<P>The returned Recordset will open with the results of the first query. To </P>
+ `1 |' _4 O7 Q1 b<P>obtain the result sets of records from subsequent queries, use the </P>
0 S2 k+ v/ w. X# ]<P>NextRecordset method. </P>
" W1 c5 ?5 b5 \7 W* r, m<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>
( l2 g& l: j: ]( T- z& z<P>dialects of SQL. Therefore, context-sensitive Help is no longer provided for </P>
, t& C, J# S: o) U- U( b- e<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>
<P>documentation for the SQL dialect of your database server when using either </P>
; u& m! |% x" c' m<P>ODBCDirect connections or pass-through queries in Microsoft Jet-connected </P>
4 m" x. ^# Z* P% o+ {<P>client/server applications. </P>
3 z+ a* i; e4 \, i4 e) k5 u4 i<P>  </P>
3 ^& o  C6 X6 P& [) 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>
, v9 ^8 D: w% g# n) s<P>For example, if two users start editing the same record, the first user to </P>
5 b% q! D5 m/ Y6 Z<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>
- x7 b2 W# o3 U1 \! r: J<P>the Delete method to delete the record, and the first user has already </P>
<P>changed it, a run-time error occurs. </P>
<P>  </P>
8 B# T% a' ^/ k& O<P>Typically, if the user gets this error while updating a record, your code </P>
<P>should refresh the contents of the fields and retrieve the newly modified </P>
<P>values. If the error occurs while deleting a record, your code could display </P>
$ m: e# q! C- P3 Z0 v5 W<P>the new record data to the user and a message indicating that the data has </P>
<P>recently changed. At this point, your code can request a confirmation that </P>
<P>the user still wants to delete the record. </P>
5 V' m: V1 n9 K' O, Y! o9 ^<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>
7 y- @) S6 J0 k8 i$ |/ v<P>later) table that has an IDENTITY column, otherwise an error may result. </P>
2 t' y) w) `, H' ~<P>  </P>
$ C& }6 l9 z5 U/ J" O<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>
# I& a" q+ j$ T$ W+ D0 A) b8 R; ^% H<P>to continue processing other statements while the query runs in the </P>
; j; R- z! E% r5 v9 D& E<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>
: d" B2 p& c! a" @5 A2 ]6 R<P>  </P>
7 V7 S8 }2 j; P0 c% J<P>Opening more than one Recordset on an ODBC data source may fail because the </P>
3 E0 l' d- A. N! J  r<P>connection is busy with a prior </P>
/ u# t# t$ Q; d2 g<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>
2 g+ W0 i' s0 S. {0 ?<P>populate the Recordset by using the MoveLast method as soon as the Recordset </P>
- P. S" x  v. ~* |( r<P>is opened. </P>
<P>  </P>
<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>
0 @; `5 u3 C7 s3 V6 t' Y<P>(known as batch updating) in an ODBCDirect workspace. Include dbOptimisticBatc </P>
" S  s& x: `; S4 J<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>
<P>changes and write them to disk as a batch. </P>
3 f' v5 w+ c$ W. ]2 k<P>  </P>
<P>Closing a Recordset with the Close method automatically deletes it from the </P>

1 F) A0 f3 z& Y0 B9 a1 w<P>Recordsets collection. </P>
<P>  </P>
<P>Note   If source refers to an SQL statement composed of a string concatenated </P>
1 a! \% \! V' A<P>with a non-integer value, and the system parameters specify a non-U.S. </P>
: R  P" o: n2 j<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>
. ~3 Y* l4 \7 z! B) _, H0 I8 l<P>to a string using your system's default decimal character, and SQL only </P>
8 T2 \! p9 b, j$ a4 [* `7 u<P>accepts U.S. decimal characters.</P>