怎样用ADO打开一个带密码的Access库？

韩冰

<>  </P>
8 p+ k; a( m; b% Q" I4 ~! S<>Creates a new Recordset object and appends it to the Recordsets collection. </P>
<>  </P>
<>Syntax </P>
<>  </P>
<>For Connection and Database objects: </P>
, [- t! r. e( g( @* k3 b<>  </P>
& U- C3 `4 N; B7 ~6 ?! }; ]' G<>Set recordset = object.OpenRecordset (source, type, options, lockedits) </P>
* A4 d2 _% S# j1 Y$ {<>  </P>
9 b. m2 F9 U7 q" Y) I0 p8 |<>For QueryDef, Recordset, and TableDef objects: </P>
<>  </P>
. ~6 w: x  H. E+ M* x, X<>Set recordset = object.OpenRecordset (type, options, lockedits) </P>
<>  </P>
<>The OpenRecordset method syntax has these parts. </P>
<>  </P>
4 h$ S; N3 X% d) Y, q+ S# c0 j# k5 X<>art    Description </P>
. h$ O6 y, v$ f2 K5 ~  u% m# F( n5 b<>recordset       An object variable that represents the Recordset object you wantt to </P>
# C0 R; X4 ]2 x! c; n: ]5 _<>open. </P>
<>object  An object variable that represents an existing object from which you </P>
<>want to create the new Recordset. </P>
. e1 G9 T* ^1 ^4 g- p: a1 Y2 C<>source  A String specifying the source of the records for the new Recordset. </P>
<>The source can be a table name, a query name, or an SQL statement that </P>
; N8 r" u( S: R( j% M<>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 J5 v' z+ W( e- ~6 ?8 s, o- G<>options Optional. A combination of constants that specify characteristics of </P>
( q6 C3 K: q% D; V0 f<>the new Recordset, as listed in Settings. </P>
1 H; Z9 r0 G" v6 o: j0 y& n<>lockedits       Optional. A constant that determines the locking for the Recordsset, </P>
6 @0 r% {1 F5 z1 B5 t<P>as specified in Settings. </P>
<P>Settings </P>
* @# J- R1 _8 M  T' B& g<P>  </P>
: s. R6 r- J+ J7 ~; p; k) `( {<P>You can use one of the following constants for the type argument. </P>
# I- T+ y' c3 a1 ^. b<P>  </P>
<P>Constant        Description </P>
; N& D1 i; D$ x4 |+ c1 {<P>  </P>
) `% a5 e. t) j<P>  </P>
<P>dbOpenTable     Opens a table-type Recordset object (Microsoft Jet workspaces </P>
<P>only). </P>
<P>dbOpenDynamic   Opens a dynamic-type Recordset object, which is similar to an </P>
" U- C' E7 G6 F2 j, Q<P>ODBC dynamic cursor. (ODBCDirect workspaces only) </P>
<P>dbOpenDynaset   Opens a dynaset-type Recordset object, which is similar to an </P>
<P>ODBC keyset cursor. </P>
: \& i  K/ Z/ |/ e. B6 j' i<P>dbOpenSnapshot  Opens a snapshot-type Recordset object, which is similar to an </P>
5 Q9 B" o, F# I' D<P>ODBC static cursor. </P>
! L) I; @7 G5 C$ N: o& r* r2 ^<P>dbOpenForwardOnly?Opens a forward-only-type Recordset object. </P>
0 l3 u' o: o0 B- ]) Q. e% x$ e<P>Note   If you open a Recordset in a Microsoft Jet workspace and you don't </P>
& H  g" s3 K0 u1 e' i. ]3 m<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>
; z3 ]& ]' H1 H+ q- B<P>Recordset. In an ODBCDirect workspace, the default setting is dbOpenForwardOnl </P>
; X9 [: v: p$ M6 R+ U<P>y. </P>
: D) N. F  e, K<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>
<P>prevents them from editing or deleting existing records (Microsoft Jet </P>
  n& T1 d/ Y0 ]6 L3 U, k% N; ~<P>dynaset-type Recordset only). </P>
<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>
<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>
5 ^" ~) A( p$ L<P>useful in applications where multiple users have simultaneous read/write </P>
+ J  m" K# }9 }7 y3 I: z: M  E<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/ o6 G. ~7 O/ P' l<P>dbForwardOnly?Creates a forward-only Recordset (Microsoft Jet snapshot-type </P>
<P>Recordset only). It is provided only for backward compatibility, and you </P>
/ U+ C$ T" \5 Z1 G. i9 U- ~* w: W% H<P>should use the dbOpenForwardOnly constant in the type argument instead of </P>
<P>using this option. </P>
8 j8 g4 @$ q  n# H# `<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>
/ z7 s: M% Y9 k* g0 n+ U<P>option, which is provided only for backward compatibility. </P>
<P>dbRunAsync      Runs an asynchronous query (ODBCDirect workspaces only). </P>
; A7 Y: N: ^% g( X<P>dbExecDirect?Runs a query by skipping SQLPrepare and directly calling </P>
/ v/ T3 a5 h6 ^& n; z" `9 Q<P>SQLExecDirect (ODBCDirect workspaces only). Use this option only when you抮e </P>
<P>not opening a Recordset based on a parameter query. For more information, see </P>
6 H6 l4 L. Y) Q' m<P>the "Microsoft ODBC 3.0 Programmer抯 Reference." </P>
# M& S( n8 K. S+ L! p- R5 K<P>dbInconsistent?Allows inconsistent updates (Microsoft Jet dynaset-type and </P>
1 G  j& x0 v9 J, L<P>snapshot-type Recordset objects only). </P>
( r& i) |$ W6 Z4 l<P>dbConsistent?Allows only consistent updates (Microsoft Jet dynaset-type and </P>
<P>snapshot-type Recordset objects only). </P>
<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>
, O6 T9 A1 P7 Q, w$ F<P>uses the dbReadOnly constant also causes an error. </P>
4 b" E* k% @% O) S( [3 c3 K<P>  </P>
) Q) Y7 M' Z4 v' ~, w<P>You can use the following constants for the lockedits argument. </P>
$ ^5 Q8 Z* Q4 Y4 Q, z' F<P>  </P>
8 L$ x; B6 |2 D" Q<P>Constant        Description </P>
: l, E# `5 [+ Z+ ^# I<P>dbReadOnly      Prevents users from making changes to the Recordset (default for </P>
; n1 @" |9 U9 D! y<P>ODBCDirect workspaces). You can use dbReadOnly in either the options argument </P>
* |; g& M4 U+ c) j<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>
<P>the Recordset in a multiuser environment. The page containing the record </P>
<P>you're editing is locked as soon as you use the Edit method (default for </P>
7 e) b+ q6 x$ V+ j! O) {2 ^( W: M" ^<P>Microsoft Jet workspaces). </P>
<P>dbOptimistic?Uses optimistic locking to determine how changes are made to the </P>
& A1 y- y2 j! k, J3 `<P>Recordset in a multiuser environment. The page containing the record is not </P>
) z" q% N9 A/ E$ k, M$ x<P>locked until the Update method is executed. </P>
8 j$ `0 k  s; D# J  m<P>dbOptimisticValue?Uses optimistic concurrency based on row values (ODBCDirect </P>
<P>workspaces only). </P>
<P>dbOptimisticBatch?Enables batch optimistic updating (ODBCDirect workspaces </P>
<P>only). </P>
<P>Remarks </P>
<P>  </P>
& S* U! ^* e- M$ n, x' K% b& l<P>In a Microsoft Jet workspace, if object refers to a QueryDef object, or a </P>
. w/ S7 q. f; E) U. p<P>dynaset- or snapshot-type Recordset, or if source refers to an SQL statement </P>
2 H. I+ @% k8 @( S' E1 C& G( D<P>or a TableDef that represents a linked table, you can't use dbOpenTable for </P>
, M' Q# R/ v& n9 W1 q, f' Y% Z<P>the type argument; if you do, a run-time error occurs. If you want to use an </P>
8 q+ d$ `$ ?! n<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>
( R& ^2 z$ q" G' X4 Z0 ]<P>database to a valid ODBC connection string. If you only need to make a single </P>
, M3 l8 t! L0 {<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>
: j# ]! {8 g! x( z<P>argument. </P>
! m4 n/ K6 U! Q; E( v* f4 R<P>  </P>
<P>If object refers to a dynaset- or snapshot-type Recordset, the new Recordset </P>
0 U, b$ g/ W1 A" Q: v! |0 J<P>is of the same type object. If object </P>
( y1 i4 H. ~3 O9 P% F<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>
/ _: B+ W$ i" D7 `<P>杢ype or ODBCDirect Recordset objects. </P>
<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>
<P>  </P>
0 Y/ k( N( ^' {# H5 c, V  p! z: ~/ f<P>"SELECT LastName, FirstName FROM Authors </P>
<P>WHERE LastName = 'Smith'; </P>
<P>SELECT Title, ISBN FROM Titles </P>
<P>WHERE ISBN Like '1-55615-*'" </P>
$ G6 I6 ?- v5 D" g<P>  </P>
<P>The returned Recordset will open with the results of the first query. To </P>
$ v" y) O5 T$ A! s) |<P>obtain the result sets of records from subsequent queries, use the </P>
) j+ j& {. c; F0 E1 L1 x<P>NextRecordset method. </P>
9 q& {, F' d! {- _4 [( x<P>  </P>
<P>Note   You can send DAO queries to a variety of different database servers </P>
4 ?. A: \7 `% S$ V<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>
2 g. s: n% M+ i, }" [8 F  P; j' Q( a<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>
  p  ~$ F% W6 o6 a7 Z<P>ODBCDirect connections or pass-through queries in Microsoft Jet-connected </P>
<P>client/server applications. </P>
& @( N$ V" s1 X# o3 w2 G7 i! r( ^& z  O<P>  </P>
<P>Use the dbSeeChanges constant in a Microsoft Jet workspace if you want to </P>
, X& v# S) K" k6 L  b<P>trap changes while two or more users are editing or deleting the same record. </P>
7 N0 N: p+ u' ~% Q/ q# y7 C6 a' A3 }<P>For example, if two users start editing the same record, the first user to </P>
3 o3 K; Z- r1 L0 [% M- |, U5 {<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>
: |! i; U: j  g6 z6 {/ c) L<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>
<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>
7 \4 R5 I- K: C5 i2 w! ]<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>
1 g- y6 o6 ?' e6 u<P>recently changed. At this point, your code can request a confirmation that </P>
<P>the user still wants to delete the record. </P>
1 E. p1 F) J& ?4 c, j3 y$ v<P>  </P>
<P>You should also use the dbSeeChanges constant if you open a Recordset in a </P>
) R' |6 |4 j) A' ]5 s# M<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>
<P>  </P>
* T' a2 ^0 Z: c# q<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>
  a3 f& M* l9 Z<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>
<P>StillExecuting property of the new Recordset. If the query takes longer to </P>
5 L- k! I/ m: ?. S# b: f9 F<P>complete than you anticipated, you can terminate execution of the query with </P>
<P>the Cancel method. </P>
9 P; N& f8 e) J" I/ T2 Q; \<P>  </P>
6 A9 A* r1 G* a6 U3 U2 Z<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>
0 O0 V2 s! I% B% m- S0 E<P>ODBCDirect, if the server supports this. Another solution is to fully </P>
4 r2 Z7 e! t8 P4 N4 g<P>populate the Recordset by using the MoveLast method as soon as the Recordset </P>
: }! S7 y' X7 n, ~! A# c<P>is opened. </P>
<P>  </P>
0 i$ ]$ a- t& }8 D& k$ @6 a$ c<P>If you open a Connection object with DefaultCursorDriver set to </P>
" L# Q6 w- H) V* z7 l9 @3 h<P>dbUseClientBatchCursor, you can open a Recordset to cache changes to the data </P>
9 F) S- [! Z" d. e6 M2 S, K<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>
$ O5 f" u; [' G) E* t( q<P>changes and write them to disk as a batch. </P>
, W  h# ]# c0 ]# i, }- v' ^7 {<P>  </P>
<P>Closing a Recordset with the Close method automatically deletes it from the </P>
- D1 ]: B" ?% X$ o9 U6 c
<P>Recordsets collection. </P>
: x7 @8 a6 Q1 H4 A9 k% t( b: j3 N9 i; @<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>
2 D+ R6 {2 F, W) h( b# j<P>lngPrice, and lngPrice = 125,50), an error occurs when you try to open the </P>
  [/ K" N2 P9 N6 M6 v6 O<P>Recordset. This is because during concatenation, the number will be converted </P>
. [! ]$ w0 {( u, T9 a' A<P>to a string using your system's default decimal character, and SQL only </P>
<P>accepts U.S. decimal characters.</P>