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>
<>  </P>
4 g- V, I+ M8 s3 i. J% Q) i- i<>Syntax </P>
& t" M1 e+ D) g" q<>  </P>
<>For Connection and Database objects: </P>
6 p5 o" O3 N' c% m<>  </P>
) Z% F2 p3 C! x9 Q<>Set recordset = object.OpenRecordset (source, type, options, lockedits) </P>
5 {; d" D2 u" }( r; u3 s. |# }<>  </P>
<>For QueryDef, Recordset, and TableDef objects: </P>
<>  </P>
( X/ J9 T$ s. f  K<>Set recordset = object.OpenRecordset (type, options, lockedits) </P>
<>  </P>
% C) R6 u) p% s' ^4 }<>The OpenRecordset method syntax has these parts. </P>
<>  </P>
<>art    Description </P>
# l1 C6 x& s0 r$ P<>recordset       An object variable that represents the Recordset object you wantt to </P>
5 V% R+ x4 W& H& {' i<>open. </P>
<>object  An object variable that represents an existing object from which you </P>
<>want to create the new Recordset. </P>
1 v; M) [" s- D1 V  R3 z8 T' R4 \<>source  A String specifying the source of the records for the new Recordset. </P>
7 T& z0 t7 R2 x5 X<>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>
<>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>
<>options Optional. A combination of constants that specify characteristics of </P>
<>the new Recordset, as listed in Settings. </P>
5 s5 @" P! Y( G7 M  f& \<>lockedits       Optional. A constant that determines the locking for the Recordsset, </P>
8 r. P7 _  |8 P& g8 I0 g; [/ z<P>as specified in Settings. </P>
<P>Settings </P>
% O* m9 c7 Z. B' g<P>  </P>
<P>You can use one of the following constants for the type argument. </P>
<P>  </P>
; b( i# S" q8 C3 h<P>Constant        Description </P>
/ b8 q( g' Z* h# r8 B, r: J% U" _<P>  </P>
  ?9 E4 H& X6 S3 i2 p  B% ]<P>  </P>
9 I) K' [* g4 _) o9 e<P>dbOpenTable     Opens a table-type Recordset object (Microsoft Jet workspaces </P>
2 R6 A" q2 N$ w" b<P>only). </P>
0 D, L: m. x0 V( B<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>
+ ?- w7 a( ~' O( F<P>ODBC keyset cursor. </P>
& @/ V" _) j* ~6 }<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>
4 }8 {) o2 g- O3 _2 U<P>Note   If you open a Recordset in a Microsoft Jet workspace and you don't </P>
/ G& P" u1 m' G2 n+ [% k% c. d<P>specify a type, OpenRecordset creates a table-type Recordset, if possible. If </P>
$ l$ ~% _* B- C  e0 ^' v) J<P>you specify a linked table or query, OpenRecordset creates a dynaset-type </P>
1 ~1 w1 {. o& `  O# C<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>
<P>argument. </P>
. z# |) I; O6 Z' Z3 [<P>  </P>
<P>Constant        Description </P>
<P>dbAppendOnly?Allows users to append new records to the Recordset, but </P>
3 @: _9 S, e/ a# U, a" U5 M8 c<P>prevents them from editing or deleting existing records (Microsoft Jet </P>
<P>dynaset-type Recordset only). </P>
/ b- y  Z4 [: t% c4 x3 T& m<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>
3 V) h9 P8 u) O<P>another user is editing (Microsoft Jet dynaset-type Recordset only). This is </P>
7 @$ v) Y; ]8 ?: C* g. A; e- @<P>useful in applications where multiple users have simultaneous read/write </P>
<P>access to the same data. </P>
" C2 {& S( j4 b% J9 J  t% h<P>dbDenyWrite?Prevents other users from modifying or adding records (Microsoft </P>
<P>Jet Recordset objects only). </P>
- x) {4 Z: Q0 O! B4 K<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>
<P>Recordset only). It is provided only for backward compatibility, and you </P>
6 |7 \% Y- g4 C7 Y/ l3 u<P>should use the dbOpenForwardOnly constant in the type argument instead of </P>
+ V. [3 m, {$ @, K# T! i% j) S+ z<P>using this option. </P>
. R1 P7 R# J% t7 O' C! [) O, B* p<P>dbReadOnly?Prevents users from making changes to the Recordset (Microsoft Jet </P>
5 `/ \9 o5 Q5 n- W5 p<P>only). The dbReadOnly constant in the lockedits argument replaces this </P>
<P>option, which is provided only for backward compatibility. </P>
9 ^! r- K0 A. G, c" t4 o<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>
<P>not opening a Recordset based on a parameter query. For more information, see </P>
<P>the "Microsoft ODBC 3.0 Programmer抯 Reference." </P>
<P>dbInconsistent?Allows inconsistent updates (Microsoft Jet dynaset-type and </P>
( Z* h% ]9 K  r6 Z' ^<P>snapshot-type Recordset objects only). </P>
<P>dbConsistent?Allows only consistent updates (Microsoft Jet dynaset-type and </P>
. O* h5 V/ R5 O/ K<P>snapshot-type Recordset objects only). </P>
<P>Note   The constants dbConsistent and dbInconsistent are mutually exclusive, </P>
6 k) x/ S7 a' M4 {, p( z2 v: j<P>and using both causes an error. Supplying a lockedits argument when options </P>
! z. Z9 ?. V! ?' Y. N<P>uses the dbReadOnly constant also causes an error. </P>
<P>  </P>
<P>You can use the following constants for the lockedits argument. </P>
<P>  </P>
0 u3 Y, R% r" m# ^  I& b0 c<P>Constant        Description </P>
) R+ B/ X0 C5 f2 @<P>dbReadOnly      Prevents users from making changes to the Recordset (default for </P>
& v( L  U; r2 R7 b; A<P>ODBCDirect workspaces). You can use dbReadOnly in either the options argument </P>
8 x" ~5 G7 x. N* O<P>or the lockedits argument, but not both. If you use it for both arguments, a </P>
<P>run-time error occurs. </P>
% Q- [3 s0 s3 H3 {6 b' I<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>
/ G' y0 c5 U& X# b# J# b7 Z<P>you're editing is locked as soon as you use the Edit method (default for </P>
<P>Microsoft Jet workspaces). </P>
- e+ p6 j: U/ I9 [, j& S<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>
<P>dbOptimisticValue?Uses optimistic concurrency based on row values (ODBCDirect </P>
, g5 S% s+ P/ K1 w8 R& \5 a) e<P>workspaces only). </P>
<P>dbOptimisticBatch?Enables batch optimistic updating (ODBCDirect workspaces </P>
<P>only). </P>
- l- D! C' Z8 ?& Z& B+ B3 _<P>Remarks </P>
<P>  </P>
1 U# X1 J4 t: N2 _4 ?2 y<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>
* A" j" f1 T3 o7 U- C% w# P<P>or a TableDef that represents a linked table, you can't use dbOpenTable for </P>
1 v4 n% W7 @9 B# e  g- Y/ U<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>
<P>pass through a Recordset opened from a Microsoft Jet-connected ODBC data </P>
; a# w+ ^+ a% R% F<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>
  `% D- R4 @0 w1 R0 N/ j<P>is of the same type object. If object </P>
, @; \7 J" V& T* M8 ~. L5 \% U<P> refers to a table-type Recordset object, the type of the new object is a </P>
6 A# V* o4 h: j% S<P>dynaset-type Recordset. You can't open new Recordset objects from forward-only </P>
; k8 k# }. o3 P<P>杢ype or ODBCDirect Recordset objects. </P>
4 k$ l1 b3 j' I2 d0 p6 O3 m<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>
<P>"SELECT LastName, FirstName FROM Authors </P>
: v" k: Z7 m+ Y4 r+ ~" y0 \3 _<P>WHERE LastName = 'Smith'; </P>
<P>SELECT Title, ISBN FROM Titles </P>
* }6 z- G6 B+ _, B  s: O5 b<P>WHERE ISBN Like '1-55615-*'" </P>
9 \; E8 c1 o: T; _. _! P<P>  </P>
<P>The returned Recordset will open with the results of the first query. To </P>
+ p* F1 u! G* _  E" ]! y<P>obtain the result sets of records from subsequent queries, use the </P>
' A0 g# L7 S. r% \5 Z<P>NextRecordset method. </P>
4 N( r6 m* l3 y, i+ ]/ @1 n<P>  </P>
- F! R8 n. D$ e& S2 z# q3 M; }9 m, O<P>Note   You can send DAO queries to a variety of different database servers </P>
* l' O0 l$ W' I$ @' Y<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>
<P>included through the Help menu. Be sure to check the appropriate reference </P>
& u! V6 y6 M9 ~# G( U<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>
" z. B% @) ^( v, O; I<P>client/server applications. </P>
# s1 @3 {) ]$ c6 u5 ~5 ]& @: O<P>  </P>
<P>Use the dbSeeChanges constant in a Microsoft Jet workspace if you want to </P>
/ m6 ^3 l$ h9 x) N7 {<P>trap changes while two or more users are editing or deleting the same record. </P>
. S) M3 J+ c& }' L! g/ k<P>For example, if two users start editing the same record, the first user to </P>
. Z7 [0 J' `' ?/ n$ k<P>execute the Update method succeeds. When the second user invokes the Update </P>
9 M: P# r/ h; 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>
0 x# ~* }0 z; i8 @  m7 u# K<P>  </P>
<P>Typically, if the user gets this error while updating a record, your code </P>
. \0 D* @% X. R8 W! E0 m0 b9 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>
, B" j. f! U; B6 ]<P>the new record data to the user and a message indicating that the data has </P>
# p' l# T4 I! f8 m<P>recently changed. At this point, your code can request a confirmation that </P>
( `) ], ?/ p. T8 Q; o/ V. S% D$ f<P>the user still wants to delete the record. </P>
$ t8 `  \" e3 M+ a<P>  </P>
7 I" ^3 X; y. [2 b0 x6 W( C8 t; n* Y3 T: L<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>
# C+ B6 K7 j4 x* g1 o/ H2 r8 G<P>later) table that has an IDENTITY column, otherwise an error may result. </P>
, v# R. l6 Y; C* o: N<P>  </P>
<P>In an ODBCDirect workspace, you can execute asynchronous queries by setting </P>
5 h0 U$ `! k# p# k0 F* q2 U<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>
7 F) ?# ~7 n& Q# i<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>
! K8 x$ V# |, u# V; x  X<P>complete than you anticipated, you can terminate execution of the query with </P>
9 }) |1 h) {/ m/ N<P>the Cancel method. </P>
" \  U9 q$ F& _5 s1 T7 i. O<P>  </P>
" Y7 Z7 c0 j, m8 c9 h! T<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>
& L8 E6 N9 z6 e9 U1 D; \<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>
% c3 l1 _- s0 [' m3 G& |<P>is opened. </P>
# L8 d: h8 v0 m8 |) ~" }. `<P>  </P>
" j: m! p. S) Q7 d: e9 u<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>
. W! M/ T  W$ c  u) ^7 A4 f<P>(known as batch updating) in an ODBCDirect workspace. Include dbOptimisticBatc </P>
' }6 i3 U  ]1 c5 |4 V( ]8 {<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>
<P>Closing a Recordset with the Close method automatically deletes it from the </P>

<P>Recordsets collection. </P>
+ V- J% S& t5 x  x' X% P0 I. B<P>  </P>
<P>Note   If source refers to an SQL statement composed of a string concatenated </P>
6 a' j" Y, Z# H: K( O<P>with a non-integer value, and the system parameters specify a non-U.S. </P>
# b. c- U. B* i& C. }" X, u6 {3 O<P>decimal character such as a comma (for example, strSQL = "PRICE &gt; " &amp; </P>
1 |6 Z* T9 j( J* J<P>lngPrice, and lngPrice = 125,50), an error occurs when you try to open the </P>
4 ?9 K8 o) E5 q+ I<P>Recordset. This is because during concatenation, the number will be converted </P>
2 J( x* B6 x( k( A: d<P>to a string using your system's default decimal character, and SQL only </P>
% l8 c( C; h0 w' C<P>accepts U.S. decimal characters.</P>