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+ C' S4 b" H9 L& n<>  </P>
% g3 j6 m# k# v<>Syntax </P>
<>  </P>
<>For Connection and Database objects: </P>
- F# w! x$ \* H<>  </P>
4 [' X* P- a, A' |: i1 c0 a<>Set recordset = object.OpenRecordset (source, type, options, lockedits) </P>
  Z9 w+ {% t' O2 H: \% ^<>  </P>
: e  R2 j8 Z* q+ {& p( Q( v<>For QueryDef, Recordset, and TableDef objects: </P>
+ f" b( y# \) k7 |5 H) K<>  </P>
<>Set recordset = object.OpenRecordset (type, options, lockedits) </P>
<>  </P>
<>The OpenRecordset method syntax has these parts. </P>
<>  </P>
<>art    Description </P>
3 P  `/ R, E2 W! n) R: S<>recordset       An object variable that represents the Recordset object you wantt to </P>
3 ?/ ?- X  S3 R; x8 F<>open. </P>
  \2 V9 Z8 b3 l0 s6 Z<>object  An object variable that represents an existing object from which you </P>
<>want to create the new Recordset. </P>
<>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>
<>returns records. For table-type Recordset objects in Microsoft Jet databases, </P>
6 S3 Q* z) R, Z( u<>the source can only be a table name. </P>
<>type    Optional. A constant that indicates the type of Recordset to open, as </P>
7 @  R' j' T# J" G<>specified in Settings. </P>
; X( z" y  L  j* d<>options Optional. A combination of constants that specify characteristics of </P>
<>the new Recordset, as listed in Settings. </P>
: V; `; X% B& Y<>lockedits       Optional. A constant that determines the locking for the Recordsset, </P>
& b; |) Z& H7 e. |4 l  E- r' |<P>as specified in Settings. </P>
3 |' h8 Y8 L7 z, }( Y<P>Settings </P>
<P>  </P>
<P>You can use one of the following constants for the type argument. </P>
<P>  </P>
<P>Constant        Description </P>
+ N, y/ N% Z% b" F2 k+ y<P>  </P>
9 H1 a6 m% \( H6 H0 D9 k" H# o0 k<P>  </P>
/ G" m5 U- @7 j: o<P>dbOpenTable     Opens a table-type Recordset object (Microsoft Jet workspaces </P>
<P>only). </P>
+ t5 |" L, a" ?, k: v1 B$ z<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>
7 s+ d8 ]4 d, d$ t<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>
; X$ J! u! Y- _! Q- y$ u<P>specify a type, OpenRecordset creates a table-type Recordset, if possible. If </P>
6 _; P4 n1 B5 D2 q& M' M<P>you specify a linked table or query, OpenRecordset creates a dynaset-type </P>
. m" f/ u' U0 {1 n! t9 b<P>Recordset. In an ODBCDirect workspace, the default setting is dbOpenForwardOnl </P>
2 I* b# D; Y. g<P>y. </P>
+ l" U* g& k+ H  z2 \<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>
; T/ i7 y; Y3 |; x6 ~<P>prevents them from editing or deleting existing records (Microsoft Jet </P>
<P>dynaset-type Recordset only). </P>
' b( w" Q& ^& B/ a$ T<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>
; x, I; Q/ y  K' ^<P>another user is editing (Microsoft Jet dynaset-type Recordset only). This is </P>
1 |& L" a4 k1 A9 U: M<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>
% C4 K: n9 s* k) J0 \, w8 J<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>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>
& G: m+ |2 L7 }) b<P>using this option. </P>
) }) ?. @+ D9 \+ s<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>
<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>
* W( R, H6 W, Y2 y* h<P>dbInconsistent?Allows inconsistent updates (Microsoft Jet dynaset-type and </P>
<P>snapshot-type Recordset objects only). </P>
% R4 C3 |) F+ J<P>dbConsistent?Allows only consistent updates (Microsoft Jet dynaset-type and </P>
<P>snapshot-type Recordset objects only). </P>
" F$ m; i  I0 u2 F( r7 e& g<P>Note   The constants dbConsistent and dbInconsistent are mutually exclusive, </P>
4 `5 V5 E* }0 J9 M, T2 Z<P>and using both causes an error. Supplying a lockedits argument when options </P>
<P>uses the dbReadOnly constant also causes an error. </P>
<P>  </P>
9 {- V' x  Q6 S, E+ R<P>You can use the following constants for the lockedits argument. </P>
9 |7 t* D5 N/ C/ P$ {<P>  </P>
<P>Constant        Description </P>
. C' f! Z* a4 V<P>dbReadOnly      Prevents users from making changes to the Recordset (default for </P>
6 a+ k3 v' j7 L# y4 F! v# ]<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>
, x6 F( a$ w0 g4 E<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>
& b1 Q8 |+ q& z/ s$ E' v<P>Microsoft Jet workspaces). </P>
( h  A6 {2 K+ A: M, F/ c<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>
' k& G9 X/ ?# {8 F  {+ v) @<P>locked until the Update method is executed. </P>
" }- B" N+ p4 J* N/ ~0 R4 u4 B/ z<P>dbOptimisticValue?Uses optimistic concurrency based on row values (ODBCDirect </P>
. k; l6 Z5 i9 M4 ^# v% Y<P>workspaces only). </P>
5 b* X- q7 y, o4 D<P>dbOptimisticBatch?Enables batch optimistic updating (ODBCDirect workspaces </P>
5 i6 @8 A- c" P. O) B* ~<P>only). </P>
& o. u, {3 h+ w( |<P>Remarks </P>
<P>  </P>
; H2 n/ e+ C4 _<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>
) F% h- r) x; W0 U# @& n. L<P>or a TableDef that represents a linked table, you can't use dbOpenTable for </P>
) @( w; ^4 ~" e% e<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>
: h- c; \, y; w8 ]5 v" K! ], }<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>
<P>source, you can improve performance by using dbOpenForwardOnly for the type </P>
<P>argument. </P>
% ?; D8 q+ u# g) K( D# N<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>
0 `# I7 p, K# H  k3 v! X) A/ u<P> refers to a table-type Recordset object, the type of the new object is a </P>
- b4 B9 {6 C6 m7 _  Y* F4 a" e. [<P>dynaset-type Recordset. You can't open new Recordset objects from forward-only </P>
<P>杢ype or ODBCDirect Recordset objects. </P>
$ j, i/ ?% h" b0 I<P>In an ODBCDirect workspace, you can open a Recordset containing more than one </P>
% i% e) l! y0 ^; Q1 H/ B<P>select query in the source argument, such as </P>
<P>  </P>
<P>"SELECT LastName, FirstName FROM Authors </P>
" t2 N$ K! V8 N<P>WHERE LastName = 'Smith'; </P>
<P>SELECT Title, ISBN FROM Titles </P>
" |$ R! O- c% {- u, ]1 U' O<P>WHERE ISBN Like '1-55615-*'" </P>
<P>  </P>
8 q3 o% t0 P3 c) K, |<P>The returned Recordset will open with the results of the first query. To </P>
7 x) J# O: @  V7 z<P>obtain the result sets of records from subsequent queries, use the </P>
. |, g7 Z" X1 ~4 b$ L. }$ ?6 ]<P>NextRecordset method. </P>
% t8 O3 [% t/ I: t+ m! e<P>  </P>
5 F! B! C( ~- m* Y# `& P<P>Note   You can send DAO queries to a variety of different database servers </P>
: {- @6 A3 X9 J$ W1 b1 h" w<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>
/ F7 N& a) h( J0 P0 s2 A<P>Microsoft Jet SQL, although online Help for Microsoft Jet SQL is still </P>
4 F' D. r) w+ y6 S0 L& I1 u<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>
7 B/ T3 ^% r" t( \<P>ODBCDirect connections or pass-through queries in Microsoft Jet-connected </P>
1 t: m- K6 o  H$ W<P>client/server applications. </P>
<P>  </P>
<P>Use the dbSeeChanges constant in a Microsoft Jet workspace if you want to </P>
( U; b' G& E3 B<P>trap changes while two or more users are editing or deleting the same record. </P>
<P>For example, if two users start editing the same record, the first user to </P>
' o( Z2 c7 b  o8 d<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>
. `( k& g- |: Z; E5 _# I<P>changed it, a run-time error occurs. </P>
<P>  </P>
2 ]* e" }+ N1 a; q! H<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>
+ u* c* R3 K; [! t6 J<P>values. If the error occurs while deleting a record, your code could display </P>
7 u# E4 d( [/ a4 T% c8 C<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>
3 U: h: B: N$ P6 w6 U/ ]2 @<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>
<P>later) table that has an IDENTITY column, otherwise an error may result. </P>
, D0 L- h3 _: b# D- b) i<P>  </P>
9 u( F  V. D+ l& Q5 _<P>In an ODBCDirect workspace, you can execute asynchronous queries by setting </P>
  G( n' |4 O4 k) \  z* Z: H<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 w$ ~8 ?; j6 `<P>background. But, you cannot access the Recordset data until the query has </P>
. z; Z* V/ C& E3 L! W<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>
  a8 i; d0 i) N9 |) m! [; [! J, @<P>the Cancel method. </P>
: Z0 T: y- R6 M, I<P>  </P>
- L, \3 f- g: Q3 H8 w1 [' K<P>Opening more than one Recordset on an ODBC data source may fail because the </P>
<P>connection is busy with a prior </P>
) J% G) m& K8 x; w, D+ E" f' p* S<P>OpenRecordset call. One way around this is to use a server-side cursor and </P>
% N, q9 g* V! l* P& @<P>ODBCDirect, if the server supports this. Another solution is to fully </P>
7 G* U# z( M8 U. w+ z' H<P>populate the Recordset by using the MoveLast method as soon as the Recordset </P>
<P>is opened. </P>
8 E! g6 I8 `+ l3 p# R" u4 Q- G<P>  </P>
/ Q7 g* @" O0 i- R$ w9 i6 J) v1 ^<P>If you open a Connection object with DefaultCursorDriver set to </P>
+ T* I% v3 M8 ~, q! q<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>
<P>h in the lockedits argument to enable update caching. See the Update method </P>
7 o/ e$ k1 a( ^. y: C<P>topic for details about how to write changes to disk immediately, or to cache </P>
% Z" F$ I$ Q: ?, _<P>changes and write them to disk as a batch. </P>
<P>  </P>
$ C  p' y. t$ N' P<P>Closing a Recordset with the Close method automatically deletes it from the </P>
7 U2 F8 b! ?$ I7 T8 |- f7 ?
" ^' |+ t. F' c6 I. N, G9 S<P>Recordsets collection. </P>
<P>  </P>
<P>Note   If source refers to an SQL statement composed of a string concatenated </P>
" _, J) @* y3 _( g9 f<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>
9 k: p5 m6 w' P* \% {<P>to a string using your system's default decimal character, and SQL only </P>
( Z8 `( y' W! L# @. ^1 K. B/ N<P>accepts U.S. decimal characters.</P>