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>
1 F& ?4 S  T* a+ d) E2 Y, K+ s  G<>  </P>
<>Syntax </P>
9 [# W- l+ q: T. K7 _<>  </P>
+ U* D, Y: C7 b& q; d& B<>For Connection and Database objects: </P>
<>  </P>
<>Set recordset = object.OpenRecordset (source, type, options, lockedits) </P>
9 Z6 m5 ?0 C, F5 r$ N<>  </P>
<>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>
<>  </P>
<>art    Description </P>
* g" [( A+ z6 r6 d, o<>recordset       An object variable that represents the Recordset object you wantt to </P>
<>open. </P>
, L. ^) K3 n4 Z$ G, _3 t2 Y7 M% `3 ~  V<>object  An object variable that represents an existing object from which you </P>
* i4 x7 {" _7 S4 z: r- ^* w$ O- S: s<>want to create the new Recordset. </P>
# z- B& p* s) Q) v<>source  A String specifying the source of the records for the new Recordset. </P>
* ?5 d! A* n  w- h<>The source can be a table name, a query name, or an SQL statement that </P>
, O, a8 |4 j, K' K- ?<>returns records. For table-type Recordset objects in Microsoft Jet databases, </P>
4 c- B) U& I- r) s0 d! Q( O<>the source can only be a table name. </P>
<>type    Optional. A constant that indicates the type of Recordset to open, as </P>
+ X# m% }) ?# _/ I- T<>specified in Settings. </P>
, \# H2 k; M1 {<>options Optional. A combination of constants that specify characteristics of </P>
<>the new Recordset, as listed in Settings. </P>
( m. \$ e; n' a1 R+ F" _<>lockedits       Optional. A constant that determines the locking for the Recordsset, </P>
<P>as specified in Settings. </P>
+ Y5 t. U7 Z! z" o/ Y% y  `0 k<P>Settings </P>
7 j4 y- B  N8 F! `<P>  </P>
/ Q3 U" j# r8 X8 K! O" L- {<P>You can use one of the following constants for the type argument. </P>
+ i6 t8 ?% C6 n/ X<P>  </P>
: O8 h, n! F7 M" g5 D7 r<P>Constant        Description </P>
# b- g* T9 F3 Q! Q2 t3 }: e2 T! z<P>  </P>
<P>  </P>
<P>dbOpenTable     Opens a table-type Recordset object (Microsoft Jet workspaces </P>
( T: Y6 F2 q% e; a! \<P>only). </P>
$ O' ^; v2 P7 N: l+ R<P>dbOpenDynamic   Opens a dynamic-type Recordset object, which is similar to an </P>
1 ~5 B( u( |1 \" e9 H3 K/ w<P>ODBC dynamic cursor. (ODBCDirect workspaces only) </P>
; ]  D. m; I6 Z' k% W7 ^<P>dbOpenDynaset   Opens a dynaset-type Recordset object, which is similar to an </P>
<P>ODBC keyset cursor. </P>
8 M. {6 M4 v. Y8 G5 r; t% w9 D<P>dbOpenSnapshot  Opens a snapshot-type Recordset object, which is similar to an </P>
1 N  L- \9 I, R6 Z& @<P>ODBC static cursor. </P>
<P>dbOpenForwardOnly?Opens a forward-only-type Recordset object. </P>
0 ]3 s4 ^; X: X) ^, P<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>
' W+ s( ~6 b. x: x* }6 i<P>Recordset. In an ODBCDirect workspace, the default setting is dbOpenForwardOnl </P>
1 h- ]& _$ u  \<P>y. </P>
<P>  </P>
% e' |3 J2 q& ?1 p<P>You can use a combination of the following constants for the options </P>
<P>argument. </P>
* q* d0 f* k3 E& }, C6 b! s<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>
<P>dynaset-type Recordset only). </P>
4 P( C* i( R8 R( H+ |! k* K+ a<P>dbSQLPassThrough?Passes an SQL statement to a Microsoft Jet-connected ODBC </P>
9 ^% T% E- Y# Y; \2 o* {<P>data source for processing (Microsoft Jet snapshot-type Recordset only). </P>
6 ?5 a( z* z/ _7 A<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>
<P>useful in applications where multiple users have simultaneous read/write </P>
<P>access to the same data. </P>
4 ]% r/ g4 g( X8 c# P. V; q<P>dbDenyWrite?Prevents other users from modifying or adding records (Microsoft </P>
<P>Jet Recordset objects only). </P>
$ C! K! j' |7 n. c1 b<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>
& z: g' D( J2 D. t  B7 H<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>
6 H  x- m& t+ x: M  C( p: k<P>using this option. </P>
<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>
<P>option, which is provided only for backward compatibility. </P>
<P>dbRunAsync      Runs an asynchronous query (ODBCDirect workspaces only). </P>
/ w- |. q3 B0 O& @: U7 m<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>
* M4 C1 ?, I: Q/ F( N4 ]: |" x<P>not opening a Recordset based on a parameter query. For more information, see </P>
! X* ^: D( g: {! g. m+ y<P>the "Microsoft ODBC 3.0 Programmer抯 Reference." </P>
( P0 |6 B) s2 c<P>dbInconsistent?Allows inconsistent updates (Microsoft Jet dynaset-type and </P>
2 l  {0 @) [0 f2 O0 K6 M; _+ J) l<P>snapshot-type Recordset objects only). </P>
% {/ z" d: u' D* R5 C<P>dbConsistent?Allows only consistent updates (Microsoft Jet dynaset-type and </P>
<P>snapshot-type Recordset objects only). </P>
( W+ @1 p( O$ R. h; g<P>Note   The constants dbConsistent and dbInconsistent are mutually exclusive, </P>
; y0 X1 s5 E% c& _/ x$ e$ y<P>and using both causes an error. Supplying a lockedits argument when options </P>
0 r$ h* ?8 L, \/ ?6 j& t<P>uses the dbReadOnly constant also causes an error. </P>
, {: B& h6 H# U6 w; g) e8 ]<P>  </P>
<P>You can use the following constants for the lockedits argument. </P>
<P>  </P>
<P>Constant        Description </P>
" a1 g. Z( x5 V+ _5 X% j* f<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>
<P>run-time error occurs. </P>
<P>dbPessimistic?Uses pessimistic locking to determine how changes are made to </P>
6 P1 [$ F/ ~% f/ o% {, j: Y<P>the Recordset in a multiuser environment. The page containing the record </P>
; z9 l# ?* H2 O1 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>
+ i$ P  Y2 B+ M) w<P>Recordset in a multiuser environment. The page containing the record is not </P>
9 o* L) f0 u# w) s) f+ E, y. t3 f, U<P>locked until the Update method is executed. </P>
<P>dbOptimisticValue?Uses optimistic concurrency based on row values (ODBCDirect </P>
<P>workspaces only). </P>
: o) L$ Q1 U8 S; T4 q9 D0 q<P>dbOptimisticBatch?Enables batch optimistic updating (ODBCDirect workspaces </P>
6 O' K8 ~1 g5 G: @( n<P>only). </P>
4 R% ?& w2 K& ~<P>Remarks </P>
<P>  </P>
- e* s" u; a9 U7 a" m6 A# g3 B<P>In a Microsoft Jet workspace, if object refers to a QueryDef object, or a </P>
: ^; C& l; m1 Z/ g! u" H* }<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>
<P>the type argument; if you do, a run-time error occurs. If you want to use an </P>
. x( V9 B& f. c  b. s7 V<P>SQL pass-through query on a linked table in a Microsoft Jet-connected ODBC </P>
) N9 J. y7 i' Z& Y9 j- h<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>
3 ^  k- [  h0 s<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>
<P>  </P>
3 k! O; N6 J8 v$ l* M<P>If object refers to a dynaset- or snapshot-type Recordset, the new Recordset </P>
- h( W! P3 q: O) S2 {<P>is of the same type object. If object </P>
, Y$ g0 B0 r% N<P> refers to a table-type Recordset object, the type of the new object is a </P>
/ A, L/ p! y/ [2 d( ^<P>dynaset-type Recordset. You can't open new Recordset objects from forward-only </P>
<P>杢ype or ODBCDirect Recordset objects. </P>
4 p, B/ {7 u; c. F; r) G<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>
2 W/ w6 T* o4 g; z) a9 r8 `<P>  </P>
<P>"SELECT LastName, FirstName FROM Authors </P>
  O. l% I# O  m) @: r<P>WHERE LastName = 'Smith'; </P>
<P>SELECT Title, ISBN FROM Titles </P>
' H* w0 e5 G+ K7 E8 x<P>WHERE ISBN Like '1-55615-*'" </P>
2 U3 `! X3 v$ l/ A<P>  </P>
<P>The returned Recordset will open with the results of the first query. To </P>
+ B! M$ ~( u8 H<P>obtain the result sets of records from subsequent queries, use the </P>
<P>NextRecordset method. </P>
<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>
; o8 c' p, G+ E! y) @<P>dialects of SQL. Therefore, context-sensitive Help is no longer provided for </P>
- c/ L, Q; ?2 E9 _6 z" D; C<P>Microsoft Jet SQL, although online Help for Microsoft Jet SQL is still </P>
) E; r8 {2 A. S) ~( l7 r1 M<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>
" i6 j! r' P3 E6 N- b% w7 y  [<P>client/server applications. </P>
5 c8 s9 U& d0 ~! H4 i/ K<P>  </P>
<P>Use the dbSeeChanges constant in a Microsoft Jet workspace if you want to </P>
* a" L, P8 [5 Q/ G9 ]+ T% F<P>trap changes while two or more users are editing or deleting the same record. </P>
) {  Z* A; |$ u' \! l<P>For example, if two users start editing the same record, the first user to </P>
5 n% Q' Z2 N3 |+ x0 X6 O<P>execute the Update method succeeds. When the second user invokes the Update </P>
: i  c# G4 n7 A( a6 P" Q<P>method, a run-time error occurs. Similarly, if the second user tries to use </P>
<P>the Delete method to delete the record, and the first user has already </P>
<P>changed it, a run-time error occurs. </P>
; b! m# p- T1 ~1 w8 O+ k<P>  </P>
8 }) u& d* y# y% u- M6 G' G' @<P>Typically, if the user gets this error while updating a record, your code </P>
+ L8 D9 G/ \% e. ^8 m<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>
<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>
+ ~. T$ }& U. {<P>the user still wants to delete the record. </P>
<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 W9 @7 ^, y9 u8 Q3 d- u<P>later) table that has an IDENTITY column, otherwise an error may result. </P>
" `1 Z" M. q6 p<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>
<P>to continue processing other statements while the query runs in the </P>
4 U" ~7 o$ _% k+ n5 s- C<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>
4 @) J$ O$ {6 T8 [  _<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>
<P>  </P>
* z/ K9 e3 L/ K* R2 O& l4 B<P>Opening more than one Recordset on an ODBC data source may fail because the </P>
- _1 B8 u5 L( Z# O$ I<P>connection is busy with a prior </P>
( G) f2 a7 I* N: _2 V4 V# X<P>OpenRecordset call. One way around this is to use a server-side cursor and </P>
! ?/ Q( G4 U2 \5 }% j( @8 y  K<P>ODBCDirect, if the server supports this. Another solution is to fully </P>
# s* k! d# V8 {9 p/ `' |8 d<P>populate the Recordset by using the MoveLast method as soon as the Recordset </P>
3 I. {$ d8 C- Y/ f! D5 v<P>is opened. </P>
; Y% H* }( ~# l" n! Q<P>  </P>
9 {( j6 W; P# N' l( C<P>If you open a Connection object with DefaultCursorDriver set to </P>
. E& ~2 _: c* f$ r  b<P>dbUseClientBatchCursor, you can open a Recordset to cache changes to the data </P>
7 V! S( j1 F, W# A3 ^<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>
& c( `" t+ B9 I5 k; d! J8 m<P>changes and write them to disk as a batch. </P>
' V, q7 c( M! i5 a! ?' `<P>  </P>
<P>Closing a Recordset with the Close method automatically deletes it from the </P>
3 X5 S5 ~: _# R
<P>Recordsets collection. </P>
+ V% `; S/ R- F, Q<P>  </P>
+ L. m( X( l3 T: _! b<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>
$ B+ @: ?( \4 p' O* E0 Q: w<P>decimal character such as a comma (for example, strSQL = "PRICE &gt; " &amp; </P>
2 ?& e4 ]( p; q  n; M<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>
8 v4 e- n$ ]! j. O+ n<P>to a string using your system's default decimal character, and SQL only </P>
<P>accepts U.S. decimal characters.</P>