怎样用ADO打开一个带密码的Access库？

韩冰

<>  </P>
" m/ D) a9 I! U. _<>Creates a new Recordset object and appends it to the Recordsets collection. </P>
<>  </P>
<>Syntax </P>
<>  </P>
- o2 _- r: K+ ^5 x- t- ^: I<>For Connection and Database objects: </P>
8 u* d- b9 P% [& x3 X# }/ S<>  </P>
<>Set recordset = object.OpenRecordset (source, type, options, lockedits) </P>
<>  </P>
<>For QueryDef, Recordset, and TableDef objects: </P>
$ \, V7 u' m- V) c7 F4 k<>  </P>
<>Set recordset = object.OpenRecordset (type, options, lockedits) </P>
<>  </P>
/ V1 g4 u/ q& W0 f* M) b1 Z; y<>The OpenRecordset method syntax has these parts. </P>
* E8 b* k4 E& V5 I<>  </P>
8 Q: ]# g" J+ s! T<>art    Description </P>
<>recordset       An object variable that represents the Recordset object you wantt to </P>
<>open. </P>
! F- ?) Y( O! K<>object  An object variable that represents an existing object from which you </P>
<>want to create the new Recordset. </P>
$ V- x* H9 J+ V- ]0 q2 I' R1 o. D<>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>
' c6 o6 i9 {5 W( k7 ?<>returns records. For table-type Recordset objects in Microsoft Jet databases, </P>
8 V. R, d. v0 K8 I8 t# 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>
4 |4 B( \: @: ]1 p<>options Optional. A combination of constants that specify characteristics of </P>
# x' E; U  \/ h# ^, u3 y0 b( K<>the new Recordset, as listed in Settings. </P>
# W) [8 T& \) D4 ~  }. C8 p<>lockedits       Optional. A constant that determines the locking for the Recordsset, </P>
<P>as specified in Settings. </P>
<P>Settings </P>
<P>  </P>
<P>You can use one of the following constants for the type argument. </P>
# G: c) ]# O$ r; y9 P: @<P>  </P>
<P>Constant        Description </P>
<P>  </P>
( y' T7 T- [% h/ L5 x<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>
<P>ODBC dynamic cursor. (ODBCDirect workspaces only) </P>
" B# [! h; [# A<P>dbOpenDynaset   Opens a dynaset-type Recordset object, which is similar to an </P>
# H7 F8 e& h8 T; i<P>ODBC keyset cursor. </P>
<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>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>
) a8 F3 O5 d) F9 ?- f<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>
<P>y. </P>
<P>  </P>
2 T. w& q7 ?" m: S! y<P>You can use a combination of the following constants for the options </P>
<P>argument. </P>
# D; z  w: G) l* H. R0 s- H! @9 u. I5 q<P>  </P>
<P>Constant        Description </P>
3 o- f5 e: g* @1 \$ }) f<P>dbAppendOnly?Allows users to append new records to the Recordset, but </P>
- ~, B& C# j( P" F/ S& ?7 q& X$ i<P>prevents them from editing or deleting existing records (Microsoft Jet </P>
<P>dynaset-type Recordset only). </P>
/ @. C/ b3 u) E& Q<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>
6 |$ x6 V- E9 \+ O<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>
3 E# t5 G+ |! O$ R# S/ f<P>useful in applications where multiple users have simultaneous read/write </P>
% l& t$ I  }0 i* x2 {<P>access to the same data. </P>
4 L* T/ P2 Z& E: u2 k9 b<P>dbDenyWrite?Prevents other users from modifying or adding records (Microsoft </P>
6 y* V) C/ r/ G* Q. O1 z<P>Jet Recordset objects only). </P>
<P>dbDenyRead?Prevents other users from reading data in a table (Microsoft Jet </P>
5 i7 l4 j  E' y& F: p% ^<P>table-type Recordset only). </P>
<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>
<P>should use the dbOpenForwardOnly constant in the type argument instead of </P>
<P>using this option. </P>
7 z5 x+ @, ~) ?2 f$ g6 K' @1 o<P>dbReadOnly?Prevents users from making changes to the Recordset (Microsoft Jet </P>
: H4 Y) _1 e: M<P>only). The dbReadOnly constant in the lockedits argument replaces this </P>
, i* k2 e" `3 U9 e& J<P>option, which is provided only for backward compatibility. </P>
% D4 o, k( N/ o6 a9 O& |( @4 T7 I<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>
, ]/ d( {4 M/ ~! }<P>not opening a Recordset based on a parameter query. For more information, see </P>
$ Y. U! @2 d4 }+ t8 P<P>the "Microsoft ODBC 3.0 Programmer抯 Reference." </P>
: s' i  p+ T! |& u, X4 A<P>dbInconsistent?Allows inconsistent updates (Microsoft Jet dynaset-type and </P>
<P>snapshot-type Recordset objects only). </P>
: N& a0 r# n3 R: e# G0 M2 V<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>
0 A, T. n' i: R<P>and using both causes an error. Supplying a lockedits argument when options </P>
1 h8 [& Z- E( h3 Z- u# C$ p<P>uses the dbReadOnly constant also causes an error. </P>
# ?( d7 `% ]8 t, b/ _<P>  </P>
# P& c: k; t$ \/ p7 q( E<P>You can use the following constants for the lockedits argument. </P>
: Z* b/ e7 ~4 T/ z& l<P>  </P>
4 t' j0 [3 Q* g6 h<P>Constant        Description </P>
<P>dbReadOnly      Prevents users from making changes to the Recordset (default for </P>
; Q, _  S  f+ P+ {/ x<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>
<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>
  e3 S- V% c2 a! e+ C6 T9 q<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>
" H. x- q3 R8 p# O/ p- G6 x: X5 p/ d<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>
; ~- `* h2 \$ s0 Z) ~  p3 s<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>
<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>
<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>
: e5 O$ y) Y3 \% s3 k<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>
6 ^2 J# ^- L2 b( Q6 }<P>argument. </P>
: H' M' d8 s) D! D<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>
- g* c! D* E2 @7 M1 r! h8 Z/ m<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>
<P>杢ype or ODBCDirect Recordset objects. </P>
<P>In an ODBCDirect workspace, you can open a Recordset containing more than one </P>
) f3 |" O6 o3 S6 k$ F; i<P>select query in the source argument, such as </P>
<P>  </P>
* ]) k- i; ]% o4 I& E! m4 k1 c<P>"SELECT LastName, FirstName FROM Authors </P>
. D/ k: j& G' L1 |" o' o4 Z# C<P>WHERE LastName = 'Smith'; </P>
3 b/ p/ g8 m* l! q  x<P>SELECT Title, ISBN FROM Titles </P>
& ^- O' @1 ]7 ~! C0 P<P>WHERE ISBN Like '1-55615-*'" </P>
7 z) d1 p8 B  M( q, ?<P>  </P>
<P>The returned Recordset will open with the results of the first query. To </P>
<P>obtain the result sets of records from subsequent queries, use the </P>
<P>NextRecordset method. </P>
. g7 b, W9 U+ U7 u/ B- i" R<P>  </P>
<P>Note   You can send DAO queries to a variety of different database servers </P>
- [- L4 E9 }" Y, l6 C. ~+ X1 ]2 ?' Q<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>
$ _0 |7 {- I; G! U9 u) 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>
2 p  F% e& j6 b' P- ^" `<P>documentation for the SQL dialect of your database server when using either </P>
1 d3 {3 V3 r+ F; N4 A<P>ODBCDirect connections or pass-through queries in Microsoft Jet-connected </P>
0 z0 V$ _2 L/ j2 t6 a<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>
6 d/ ]+ t# [4 d<P>For example, if two users start editing the same record, the first user to </P>
6 `; I6 u; c2 l; k. m1 R<P>execute the Update method succeeds. When the second user invokes the Update </P>
: _, O0 f$ ~' m- ^, D! U<P>method, a run-time error occurs. Similarly, if the second user tries to use </P>
" Q' \# B9 o; j- o# ^: F  F<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>
6 N6 M8 B! M8 J. M1 M<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>
<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>
* u+ F- {. C0 S3 Y3 b6 n2 N4 v0 s; E: v1 O<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>
! ?8 \% x, V6 z3 S' x: h<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>
# h0 O8 t% \3 i2 j9 F# 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>
9 `7 b4 M" n' A9 d  t" q, v<P>  </P>
& O5 M8 G4 @. u6 h& `<P>Opening more than one Recordset on an ODBC data source may fail because the </P>
) M6 i: ]3 F; f3 I7 c! }9 k: @1 ^<P>connection is busy with a prior </P>
" f) g9 B9 Y. S! T<P>OpenRecordset call. One way around this is to use a server-side cursor and </P>
5 W& `" c- P5 p4 a1 I8 l<P>ODBCDirect, if the server supports this. Another solution is to fully </P>
$ ~$ F9 u: w: g8 Q: N<P>populate the Recordset by using the MoveLast method as soon as the Recordset </P>
<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>
* _4 @: [. w6 a% x<P>(known as batch updating) in an ODBCDirect workspace. Include dbOptimisticBatc </P>
* T- ?5 \+ z  L5 Z9 U<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>
<P>  </P>
3 t* |9 b) ]1 v0 E<P>Closing a Recordset with the Close method automatically deletes it from the </P>
8 _; |  X* Y* D
<P>Recordsets collection. </P>
, S  x* q, D* Z# @. P8 g<P>  </P>
! R# L1 A, x. x( z9 t<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>
; `5 Z3 @8 u6 ], @<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>
! m! l# u, j/ V' Y' B% V6 N<P>to a string using your system's default decimal character, and SQL only </P>
7 N% L+ O5 Y" R1 n<P>accepts U.S. decimal characters.</P>