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>
' t$ L9 s7 r4 ^<>  </P>
<>Syntax </P>
<>  </P>
+ Z) R, ^5 i6 ]  M<>For Connection and Database objects: </P>
  t4 t$ N! t+ n) t+ Q/ w9 g<>  </P>
<>Set recordset = object.OpenRecordset (source, type, options, lockedits) </P>
<>  </P>
, J. q/ T' `) _; C4 z) F& i<>For QueryDef, Recordset, and TableDef objects: </P>
<>  </P>
& ?" [- ]& G0 H5 j<>Set recordset = object.OpenRecordset (type, options, lockedits) </P>
<>  </P>
<>The OpenRecordset method syntax has these parts. </P>
<>  </P>
<>art    Description </P>
6 Y( P$ Z  ^% [: @<>recordset       An object variable that represents the Recordset object you wantt to </P>
<>open. </P>
) j" _# T, \9 F4 _, {<>object  An object variable that represents an existing object from which you </P>
" q2 u* k0 ~. E8 z0 w  _3 m+ b<>want to create the new Recordset. </P>
6 q, ~, i% `( z$ L& q<>source  A String specifying the source of the records for the new Recordset. </P>
9 x" X$ [" Q8 O5 z* w5 f<>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>
0 o+ X. q) @* Z( M8 i<>type    Optional. A constant that indicates the type of Recordset to open, as </P>
<>specified in Settings. </P>
" O( H% ^) B' T2 l# D3 S, O<>options Optional. A combination of constants that specify characteristics of </P>
3 A! V# O+ ?. H<>the new Recordset, as listed in Settings. </P>
0 S7 l: A; A3 N; Z: ^<>lockedits       Optional. A constant that determines the locking for the Recordsset, </P>
0 [) h; R/ f' H9 w1 c5 i6 `<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>
- d# J! e! C  h% H8 t+ \3 X<P>  </P>
<P>Constant        Description </P>
3 Y1 [- R! Z, Y" D3 B& q5 Y  x<P>  </P>
9 k2 G+ o. i& O! K* J6 J$ C5 q<P>  </P>
+ \+ g) {. N9 ?, u<P>dbOpenTable     Opens a table-type Recordset object (Microsoft Jet workspaces </P>
& e8 J* ]# T- U9 Z<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>
$ Y" z& l: R/ h8 A' S. E3 X<P>dbOpenSnapshot  Opens a snapshot-type Recordset object, which is similar to an </P>
<P>ODBC static cursor. </P>
9 C4 H6 _+ o9 e. P( l) E% `<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>
<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>
/ \6 F, S3 Z+ v' z3 u& W2 x  i<P>  </P>
! E6 E% [$ \" w0 E7 L( Q1 _7 e2 Y<P>You can use a combination of the following constants for the options </P>
<P>argument. </P>
  H# R( o1 ~6 J1 P<P>  </P>
# b4 O5 T6 Z- Z5 v8 K% n<P>Constant        Description </P>
+ `7 X' [8 b3 p- J1 u- ~3 X: P+ g<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>
! k5 \0 {# v8 q  B4 D7 ?<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>
+ m- a. L$ D$ t+ v% ]1 O<P>dbSeeChanges    Generates a run-time error if one user is changing data that </P>
: G/ o, y' h) M4 J<P>another user is editing (Microsoft Jet dynaset-type Recordset only). This is </P>
( q- G: w9 o- a& M<P>useful in applications where multiple users have simultaneous read/write </P>
% Y# m* y: L5 v<P>access to the same data. </P>
<P>dbDenyWrite?Prevents other users from modifying or adding records (Microsoft </P>
<P>Jet Recordset objects only). </P>
* U  b, ~: h0 H% c  a<P>dbDenyRead?Prevents other users from reading data in a table (Microsoft Jet </P>
5 d4 Z( I  W8 d) a" C: {<P>table-type Recordset only). </P>
<P>dbForwardOnly?Creates a forward-only Recordset (Microsoft Jet snapshot-type </P>
5 z; }0 w$ Y" K/ e<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>
<P>dbReadOnly?Prevents users from making changes to the Recordset (Microsoft Jet </P>
+ `# j7 `# G' f1 u, _; Y<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>
6 U( B/ V: t) E# g<P>dbExecDirect?Runs a query by skipping SQLPrepare and directly calling </P>
/ B- }) |. Z! F9 ~1 c9 y* y5 J: z<P>SQLExecDirect (ODBCDirect workspaces only). Use this option only when you抮e </P>
& l% P2 J1 e# v% \" D# |<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>
<P>snapshot-type Recordset objects only). </P>
+ [1 {. e& a' ]$ d<P>dbConsistent?Allows only consistent updates (Microsoft Jet dynaset-type and </P>
& l$ P1 {  u* Q' C$ }<P>snapshot-type Recordset objects only). </P>
<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>
<P>  </P>
( p( U# |! U$ S9 `! M( o! }<P>You can use the following constants for the lockedits argument. </P>
<P>  </P>
6 W3 b% [) O5 M5 i<P>Constant        Description </P>
<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>
, D/ Z8 X! b+ o8 K<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>
! t. M8 ^7 h5 f<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>
<P>Microsoft Jet workspaces). </P>
<P>dbOptimistic?Uses optimistic locking to determine how changes are made to the </P>
5 }4 |6 m( a; i" P  |( X9 i<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>
<P>workspaces only). </P>
<P>dbOptimisticBatch?Enables batch optimistic updating (ODBCDirect workspaces </P>
, L! y$ _: A0 N+ u<P>only). </P>
<P>Remarks </P>
3 ~8 o- n: Z  i6 ^3 Y/ j" T$ `<P>  </P>
<P>In a Microsoft Jet workspace, if object refers to a QueryDef object, or a </P>
+ Z- U  g7 S& l! |5 g3 N) S<P>dynaset- or snapshot-type Recordset, or if source refers to an SQL statement </P>
5 Q. A( H2 {" ]4 `% t<P>or a TableDef that represents a linked table, you can't use dbOpenTable for </P>
' p1 q1 O& `6 _9 f" D6 m' L<P>the type argument; if you do, a run-time error occurs. If you want to use an </P>
5 {6 {5 ~! a9 ?& R3 v<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>
# S+ g. z7 B/ [5 K. N<P>database to a valid ODBC connection string. If you only need to make a single </P>
3 |/ m* q9 L' m6 j0 V: c<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>
$ q8 j* d2 l1 J7 F% i5 `<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>
$ E# I4 v  e# i( Y6 @( q' Q3 o<P>select query in the source argument, such as </P>
* Q4 X+ S$ g# }<P>  </P>
<P>"SELECT LastName, FirstName FROM Authors </P>
<P>WHERE LastName = 'Smith'; </P>
<P>SELECT Title, ISBN FROM Titles </P>
) R2 O2 t1 t1 @/ b+ |& n<P>WHERE ISBN Like '1-55615-*'" </P>
<P>  </P>
8 X9 f# V' L8 h3 _) c<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>
4 i; S! A1 x; m" o<P>NextRecordset method. </P>
; |) f* l  `# Q' q. M, X<P>  </P>
<P>Note   You can send DAO queries to a variety of different database servers </P>
; O! y% v; l( 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>
( D! i1 w+ B! q4 J+ L2 j% j<P>Microsoft Jet SQL, although online Help for Microsoft Jet SQL is still </P>
; {9 _! l% M0 s3 C- G<P>included through the Help menu. Be sure to check the appropriate reference </P>
: }; [9 N; f: D2 A  {0 k% _<P>documentation for the SQL dialect of your database server when using either </P>
: M& x( s0 B4 T7 Y4 o<P>ODBCDirect connections or pass-through queries in Microsoft Jet-connected </P>
! A6 `8 V0 R4 p; F, h<P>client/server applications. </P>
<P>  </P>
$ ^2 k. ^2 {/ V" f<P>Use the dbSeeChanges constant in a Microsoft Jet workspace if you want to </P>
( K. C- b6 D- F<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>
<P>execute the Update method succeeds. When the second user invokes the Update </P>
' @& k9 H9 w, Z! M+ A/ T  b<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>
0 U& l2 H: x( V5 l<P>changed it, a run-time error occurs. </P>
/ o6 h5 ]; X% `<P>  </P>
<P>Typically, if the user gets this error while updating a record, your code </P>
* R0 I8 L) j; ]<P>should refresh the contents of the fields and retrieve the newly modified </P>
8 O7 t# e8 m4 P0 B/ g* K<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>
1 S5 Z2 w$ B9 c( D, ~5 P<P>recently changed. At this point, your code can request a confirmation that </P>
! I' n, S! J1 F' h<P>the user still wants to delete the record. </P>
<P>  </P>
/ `% ]# C2 A" Y<P>You should also use the dbSeeChanges constant if you open a Recordset in a </P>
' J. w+ H: c2 h) Y; |<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>
+ Y# Q$ o+ Z- ]* i' `( m3 V0 R<P>  </P>
& h) c2 X6 o" Q" a5 u! T<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>
" D# J$ N! r/ A/ J3 _<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>
2 n1 J! T. O# ~8 N3 }<P>completed. To determine whether the query has finished executing, check the </P>
% ~5 \; z! s8 ^4 r2 g# c<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>
; J7 G/ E% ^" ]0 V<P>the Cancel method. </P>
9 s6 ]1 k2 ^5 n4 H2 ~3 m& \<P>  </P>
<P>Opening more than one Recordset on an ODBC data source may fail because the </P>
" A3 @4 S3 V6 c% w" G<P>connection is busy with a prior </P>
<P>OpenRecordset call. One way around this is to use a server-side cursor and </P>
1 z3 ]! J% m6 M. u% o& j<P>ODBCDirect, if the server supports this. Another solution is to fully </P>
  M; Q0 h' U8 n6 S+ }, s6 r* t<P>populate the Recordset by using the MoveLast method as soon as the Recordset </P>
% t9 W+ t; p3 B4 y4 U+ l4 h<P>is opened. </P>
$ t  E+ P* z  b) r<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>
<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>
<P>changes and write them to disk as a batch. </P>
( ^' k/ m% \; D5 U) J<P>  </P>
<P>Closing a Recordset with the Close method automatically deletes it from the </P>

" r$ j, U8 t- ?' J<P>Recordsets collection. </P>
<P>  </P>
<P>Note   If source refers to an SQL statement composed of a string concatenated </P>
3 A! s- K2 `' D) d$ j0 ~<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>
/ }# h; l  H( U8 @' s2 q' X<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>
, n! f) J% E% [. i- U! E" c<P>to a string using your system's default decimal character, and SQL only </P>
" G0 d  ~9 k$ Y% D5 D2 r<P>accepts U.S. decimal characters.</P>