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>
; W; f5 V# S- r: s# S$ K: E! x4 v) C<>  </P>
<>Syntax </P>
9 ~/ d: S$ ]7 Z# N( R! ?0 q<>  </P>
1 U$ J' C- E! q/ [; D<>For Connection and Database objects: </P>
( Y8 Y' U1 n2 {( N- s<>  </P>
<>Set recordset = object.OpenRecordset (source, type, options, lockedits) </P>
<>  </P>
<>For QueryDef, Recordset, and TableDef objects: </P>
<>  </P>
! X( L- d  @" n3 T. C, |* `<>Set recordset = object.OpenRecordset (type, options, lockedits) </P>
<>  </P>
9 O1 U* l, g/ Y; w<>The OpenRecordset method syntax has these parts. </P>
4 ^8 h! K. Z# i; b! c) ]<>  </P>
! J- m; j- K  @' G0 p. N<>art    Description </P>
<>recordset       An object variable that represents the Recordset object you wantt to </P>
<>open. </P>
) @" @# o% }! e0 c# Y( K<>object  An object variable that represents an existing object from which you </P>
1 W& u4 s0 b5 Y5 i0 s0 I<>want to create the new Recordset. </P>
<>source  A String specifying the source of the records for the new Recordset. </P>
2 u9 t5 @: E& b+ J! _- i6 @<>The source can be a table name, a query name, or an SQL statement that </P>
2 m) n1 D0 i7 p+ Q& ~7 g<>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>
. F& ^  }. C- t<>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>
  j( h' V. [" _<P>as specified in Settings. </P>
<P>Settings </P>
<P>  </P>
4 y" z1 c9 O; g$ G( b<P>You can use one of the following constants for the type argument. </P>
) F. R+ J7 m1 z1 V* I3 C<P>  </P>
* V7 S' F# [/ D' G- C<P>Constant        Description </P>
<P>  </P>
' ?* }% p! v: K+ Y5 k- m% e/ f<P>  </P>
% [) k! S2 a+ \) Z<P>dbOpenTable     Opens a table-type Recordset object (Microsoft Jet workspaces </P>
5 \6 W5 t" r4 l. v- j& J<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>
<P>dbOpenDynaset   Opens a dynaset-type Recordset object, which is similar to an </P>
<P>ODBC keyset cursor. </P>
<P>dbOpenSnapshot  Opens a snapshot-type Recordset object, which is similar to an </P>
<P>ODBC static cursor. </P>
2 g3 l5 Y' P" v<P>dbOpenForwardOnly?Opens a forward-only-type Recordset object. </P>
# @* p- T3 |  i9 x/ J<P>Note   If you open a Recordset in a Microsoft Jet workspace and you don't </P>
; G' ]0 m3 a: O* e4 {<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>
<P>Recordset. In an ODBCDirect workspace, the default setting is dbOpenForwardOnl </P>
2 S* r  Y( u" I0 w8 `0 G<P>y. </P>
" ]' D! z0 T1 g7 j7 A8 \( B<P>  </P>
$ G( ?+ B2 g! `) V0 J% v<P>You can use a combination of the following constants for the options </P>
* T+ y6 q) X! s) R# {" P<P>argument. </P>
<P>  </P>
<P>Constant        Description </P>
+ _+ t2 w  \) Q# ~6 O<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>
, m( M7 n7 o7 Z& R<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>
+ f2 W3 Z# e+ {2 j" @( [  R2 _<P>another user is editing (Microsoft Jet dynaset-type Recordset only). This is </P>
3 ^0 b, R7 E3 Y! J<P>useful in applications where multiple users have simultaneous read/write </P>
<P>access to the same data. </P>
<P>dbDenyWrite?Prevents other users from modifying or adding records (Microsoft </P>
1 D1 M8 U4 t4 u4 B<P>Jet Recordset objects only). </P>
<P>dbDenyRead?Prevents other users from reading data in a table (Microsoft Jet </P>
6 S! e% Q! W7 w! K4 f; o<P>table-type Recordset only). </P>
0 O0 D2 F- `& t( w) i6 h7 ?<P>dbForwardOnly?Creates a forward-only Recordset (Microsoft Jet snapshot-type </P>
: M0 e! \' q/ j1 T- }& w9 ]' a<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>
1 K# e3 U+ N6 j<P>dbReadOnly?Prevents users from making changes to the Recordset (Microsoft Jet </P>
" k9 k% T9 e2 W' k( B" b% Y/ v<P>only). The dbReadOnly constant in the lockedits argument replaces this </P>
<P>option, which is provided only for backward compatibility. </P>
: ]7 J$ S$ v8 c8 D8 d/ B6 d<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>
/ n3 b" o' l( j9 L. z  D<P>not opening a Recordset based on a parameter query. For more information, see </P>
6 p9 G' ^6 t1 Y( e- Y; C2 D1 R! V<P>the "Microsoft ODBC 3.0 Programmer抯 Reference." </P>
<P>dbInconsistent?Allows inconsistent updates (Microsoft Jet dynaset-type and </P>
8 w  n" I1 w/ H; t<P>snapshot-type Recordset objects only). </P>
<P>dbConsistent?Allows only consistent updates (Microsoft Jet dynaset-type and </P>
4 j( x' J2 W2 a9 U) X) T0 Z<P>snapshot-type Recordset objects only). </P>
9 d4 J$ c5 h! A3 D: X3 R<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>
<P>uses the dbReadOnly constant also causes an error. </P>
" d2 I+ `- n% h8 K/ \9 P; ^8 d<P>  </P>
<P>You can use the following constants for the lockedits argument. </P>
<P>  </P>
+ S' x) J6 F- ~2 g4 Z! l1 }<P>Constant        Description </P>
! G, T4 G! P- H  a- o<P>dbReadOnly      Prevents users from making changes to the Recordset (default for </P>
1 b3 g( J) t2 ]- S2 F3 K<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>
- x. {3 H, L8 a2 T; R2 h<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>
% K& v( X; z/ j) ]<P>Microsoft Jet workspaces). </P>
3 n8 \3 G9 g. v* J<P>dbOptimistic?Uses optimistic locking to determine how changes are made to the </P>
  C& R" e: _; b, N# \<P>Recordset in a multiuser environment. The page containing the record is not </P>
<P>locked until the Update method is executed. </P>
- [4 X5 r2 A  D& q. k' k<P>dbOptimisticValue?Uses optimistic concurrency based on row values (ODBCDirect </P>
<P>workspaces only). </P>
+ w3 S( W; T1 y6 X<P>dbOptimisticBatch?Enables batch optimistic updating (ODBCDirect workspaces </P>
<P>only). </P>
<P>Remarks </P>
<P>  </P>
<P>In a Microsoft Jet workspace, if object refers to a QueryDef object, or a </P>
3 @( a# g  I$ Y* g% L+ U<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>
1 M, m8 T* ^% u, z! T* F# b; Z! {<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>
  [0 p& y* @4 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>
<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>
: ^- G) Z- g! }( J6 `: F* i& ^8 b2 p; A<P>dynaset-type Recordset. You can't open new Recordset objects from forward-only </P>
<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>
( j/ F- R6 }  [6 u- Z) P  w* c; f<P>  </P>
" @7 g3 Q* X2 K' C<P>"SELECT LastName, FirstName FROM Authors </P>
) a  P& J9 O4 _  E5 x<P>WHERE LastName = 'Smith'; </P>
<P>SELECT Title, ISBN FROM Titles </P>
5 a, \* }) ?) i/ T2 ?<P>WHERE ISBN Like '1-55615-*'" </P>
2 v: b7 p9 X# s<P>  </P>
<P>The returned Recordset will open with the results of the first query. To </P>
0 a# ?" M+ F- G/ U<P>obtain the result sets of records from subsequent queries, use the </P>
<P>NextRecordset method. </P>
, R6 f" ~$ E% p<P>  </P>
* U$ [5 O: c* U( F2 R- W<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>
: X. H& S; A, p5 Q- B9 f1 o8 b3 B" Q<P>included through the Help menu. Be sure to check the appropriate reference </P>
+ f/ i+ ?9 n( J; R0 F' O<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>
0 R; y( \4 r$ o; i: S<P>client/server applications. </P>
<P>  </P>
2 Z8 `# X# a' v5 Q6 q<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>
3 x# ^3 [" Z2 G<P>For example, if two users start editing the same record, the first user to </P>
3 n$ D1 x" Y9 M$ k6 _2 q6 r# Y<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>
<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>
<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>
" f% t; {2 g2 B6 b6 ?<P>recently changed. At this point, your code can request a confirmation that </P>
<P>the user still wants to delete the record. </P>
3 O8 S- l9 _7 W! S<P>  </P>
% J$ ^' K9 R! e5 r0 J, e<P>You should also use the dbSeeChanges constant if you open a Recordset in a </P>
1 l4 Q5 Y4 y( r- F, \<P>Microsoft Jet-connected ODBC workspace against a Microsoft SQL Server 6.0 (or </P>
) \9 J2 ]' C1 p! I4 T/ o% x<P>later) table that has an IDENTITY column, otherwise an error may result. </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>
<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>
  @! \) X) A' t* I9 |7 d% c1 ]<P>StillExecuting property of the new Recordset. If the query takes longer to </P>
9 k; {- s! l7 X5 h' P! x<P>complete than you anticipated, you can terminate execution of the query with </P>
6 o- l) G, i/ E( g/ P" E9 i<P>the Cancel method. </P>
<P>  </P>
* a, L% k) b+ }. }7 [<P>Opening more than one Recordset on an ODBC data source may fail because the </P>
<P>connection is busy with a prior </P>
/ C5 ]7 \* u' K<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>
<P>populate the Recordset by using the MoveLast method as soon as the Recordset </P>
<P>is opened. </P>
) b7 i4 c9 }9 s* y. H+ Y% z4 j9 Z" H<P>  </P>
- f) u- u1 n9 w2 R- A% `1 f+ @6 f<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>
' k) a- l6 e5 n4 T7 O( `<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>
0 _) c/ R9 B7 f+ N<P>  </P>
<P>Closing a Recordset with the Close method automatically deletes it from the </P>
0 d; Z4 a. `  _; U  W1 w0 Y
9 c, \" C( n# O8 r7 A2 p<P>Recordsets collection. </P>
<P>  </P>
% r' v# _2 P2 z3 m6 V5 D& K<P>Note   If source refers to an SQL statement composed of a string concatenated </P>
( Q( h* O! R0 G" O& Q<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>
  y8 t# r4 _7 h" @) q  ]" f' R- X<P>to a string using your system's default decimal character, and SQL only </P>
& b' y( K  o% U5 k! {$ t9 J<P>accepts U.S. decimal characters.</P>