X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/6b2878de13d4159bbb399c862b00762a94f07be7..d6d8b172806a21e5c5c341f75b0f1213d5d52e94:/docs/latex/wx/tdb.tex?ds=sidebyside diff --git a/docs/latex/wx/tdb.tex b/docs/latex/wx/tdb.tex index 449efdbfc3..71a470d202 100644 --- a/docs/latex/wx/tdb.tex +++ b/docs/latex/wx/tdb.tex @@ -1,29 +1,9 @@ \section{Database classes overview}\label{odbcoverview} -\normalboxd{The more sophisticated wxODBC classes (wxDb/wxDbTable) are the -recommended classes for doing database/ODBC work with wxWindows. These new -classes replace the wxWindows v1.6x classes wxDatabase. Documentation for the -old wxDatabase class and its associated classes is still -included in the class documentation and in this overview section, but support -for these old classes has been phased out, and all future development work -is being done solely on the new wxDb/wxDbTable classes.} - -\subsection{Different ODBC Class Libraries in wxWindows} - -Following is a detailed overview of how to use the wxWindows ODBC classes - \helpref{wxDb}{wxdb} +Following is a detailed overview of how to use the wxWidgets ODBC classes - \helpref{wxDb}{wxdb} and \helpref{wxDbTable}{wxdbtable} and their associated functions. These are the ODBC classes donated by Remstar International, and are collectively -referred to herein as the wxODBC classes. Since their initial inclusion with -wxWindows v2.x, they have become the recommended wxWindows classes for database -access. - -An older version of some classes ported over from wxWindows v1.68 still exist -(see \helpref{wxDatabase}{wxdatabase} in odbc.cpp), but are now deprecated in favor of the more -robust and comprehensive wxDb/wxDbTable classes. All current and future -feature development, as well as active debugging, are only being done on -the wxODBC classes. Documentation for the older classes is still provided -in this manual. The \helpref{wxDatabase overview}{wxdatabaseoverview} of the -older classes follows the overview of the new classes. +referred to herein as the wxODBC classes. \subsection{wxDb/wxDbTable wxODBC Overview}\label{wxodbcoverview} @@ -45,18 +25,20 @@ software with these classes, but at the time of the writing of this document, users have successfully used the classes with the following datasources: \begin{itemize}\itemsep=0pt -\item Oracle (v7, v8, v8i) -\item Sybase (ASA and ASE) -\item MS SQL Server (v7 - minimal testing) -\item MS Access (97 and 2000) -\item MySQL +\item DB2 \item DBase (IV, V)** -\item PostgreSQL +\item Firebird \item INFORMIX -\item VIRTUOSO -\item DB2 \item Interbase +\item MS SQL Server (v7 - minimal testing) +\item MS Access (97, 2000, 2002, and 2003) +\item MySQL (2.x and 3.5 - use the 2.5x drivers though) +\item Oracle (v7, v8, v8i) \item Pervasive SQL +\item PostgreSQL +\item Sybase (ASA and ASE) +\item XBase Sequiter +\item VIRTUOSO \end{itemize} An up-to-date list can be obtained by looking in the comments of the function @@ -172,7 +154,7 @@ returned. For each result set, a cursor is maintained (typically by the database) which keeps track of where in the result set the user currently is. Depending on the database, ODBC driver, and how you configured the -wxWindows ODBC settings in setup.h (see \helpref{wxODBC - Compiling}{wxodbccompiling}), cursors can be +wxWidgets ODBC settings in setup.h (see \helpref{wxODBC - Compiling}{wxodbccompiling}), cursors can be either forward or backward scrolling. At a minimum, cursors must scroll forward. For example, if a query resulted in a result set with 100 rows, as the data is read by the client application, it will read row 1, then 2, @@ -258,7 +240,7 @@ the datasource will only be available to the user who configured the DSN. Under Unix, iODBC is used for implementation of the ODBC API. To compile the wxODBC classes, you must first obtain iODBC from \urlref{http://www.iodbc.org}{www.iodbc.org} and install it. -(Note: wxWindows currently includes a version of iODBC.) Then you must create the file "~/.odbc.ini" (or optionally create +(Note: wxWidgets currently includes a version of iODBC.) Then you must create the file "~/.odbc.ini" (or optionally create "/etc/odbc.ini" for access for all users on the system). This file contains the settings for your system/datasource. Below is an example section of a odbc.ini file for use with the "samples/db" sample program using MySQL: @@ -277,7 +259,7 @@ odbc.ini file for use with the "samples/db" sample program using MySQL: \subsection{wxODBC - Compiling}\label{wxodbccompiling} -The wxWindows setup.h file has several settings in it pertaining to compiling +The wxWidgets setup.h file has several settings in it pertaining to compiling the wxODBC classes. \begin{twocollist}\itemsep=0pt @@ -290,10 +272,10 @@ only forward scrolling cursors, or forward and backward scrolling cursors (see the section in "WHERE TO START" on cursors for more information on cursors). This default can be overridden by passing a second parameter to either the \helpref{wxDbGetConnection}{wxdbfunctions} or -\helpref{wxDb constructor}{wxdbconstr}. The default is 1.} +\helpref{wxDb constructor}{wxdbctor}. The default is 1.} \twocolitem{wxODBC\_BACKWARD\_COMPATABILITY}{Between v2.0 and 2.2, massive renaming efforts were done to the ODBC classes to get naming conventions -similar to those used throughout wxWindows, as well as to preface all wxODBC +similar to those used throughout wxWidgets, as well as to preface all wxODBC classes names and functions with a wxDb preface. Because this renaming would affect applications written using the v2.0 names, this compile-time directive was added to allow those programs written for v2.0 to still compile using the @@ -308,11 +290,9 @@ is 0.} You are required to include the "odbc32.lib" provided by your compiler vendor in the list of external libraries to be linked in. If using the makefiles -supplied with wxWindows, this library should already be included for use with +supplied with wxWidgets, this library should already be included for use with makefile.b32, makefile.vc, and makefile.g95. -You cannot compile the wxODBC classes under Win16 - sorry. - \normalbox{MORE TO COME} {\it Under Unix} @@ -341,7 +321,7 @@ to when first starting to use the classes. Throughout the steps, small snippets of code are provided to show the syntax of performing the step. A complete code snippet is provided at the end of this overview that shows a complete working flow of all these steps (see -\helpref{wxODBC - Sample Code {\tt\#}1}{wxodbcsamplecode1}). +\helpref{wxODBC - Sample Code}{wxodbcsamplecode1}). {\bf Define datasource connection information} @@ -351,7 +331,7 @@ Authorization string (password). A fourth piece of information, a default directory indicating where the data file is stored, is required for Text and dBase drivers for ODBC. -The wxWindows data class wxDbConnectInf exists for holding all of these +The wxWidgets data class wxDbConnectInf exists for holding all of these values, plus some others that may be desired. The 'Henv' member is the environment handle used to access memory for use by the @@ -404,8 +384,8 @@ member. \begin{verbatim} wxDbConnectInf DbConnectInf; - DbConnectInf.SetDsn,"MyDSN"); - DbConnectInf.SetUserID,"MyUserName"); + DbConnectInf.SetDsn("MyDSN"); + DbConnectInf.SetUserID("MyUserName"); DbConnectInf.SetPassword("MyPassword"); DbConnectInf.SetDefaultDir(""); \end{verbatim} @@ -424,7 +404,7 @@ the necessary handle: \end{verbatim} When the wxDbConnectInf::AllocHenv() function is called successfully, a -value of TRUE will be returned. A value of FALSE means allocation failed, +value of true will be returned. A value of false means allocation failed, and the handle will be undefined. A shorter form of doing the above steps is encapsulated into the @@ -518,7 +498,7 @@ One final note on creating a connection. When a connection is created, it will default to only allowing cursor scrolling to be either forward only, or both backward and forward scrolling. The default behavior is determined by the setting {\tt wxODBC\_FWD\_ONLY\_CURSORS} in setup.h when you -compile the wxWindows library. The library default is to only support +compile the wxWidgets library. The library default is to only support forward scrolling cursors only, though this can be overridden by parameters for wxDb() constructor or the \helpref{wxDbGetConnection}{wxdbfunctions} function. All datasources and ODBC drivers must support forward scrolling @@ -579,9 +559,9 @@ can specify anywhere from one column up to all columns in the table. \begin{verbatim} table->SetColDefs(0, "FIRST_NAME", DB_DATA_TYPE_VARCHAR, FirstName, - SQL_C_CHAR, sizeof(name), TRUE, TRUE); + SQL_C_WXCHAR, sizeof(FirstName), true, true); table->SetColDefs(1, "LAST_NAME", DB_DATA_TYPE_VARCHAR, LastName, - SQL_C_CHAR, sizeof(LastName), TRUE, TRUE); + SQL_C_WXCHAR, sizeof(LastName), true, true); \end{verbatim} Notice that column definitions start at index 0 and go up to one less than @@ -644,7 +624,7 @@ if SQL logging is turned on for the classes. To use the table and the definitions that are now set up, we must first define what data we want the datasource to collect in to a result set, tell -it where to get the data from, and in what sequence we want the data returned. +it where to get the data from, and in which sequence we want the data returned. \begin{verbatim} // the WHERE clause limits/specifies which rows in the table @@ -718,7 +698,7 @@ syntax problem in the WHERE clause that was specified. The exact SQL parsing the table's database connection's "errorList[]" array member for the stored text of the error. -When the \helpref{wxDbTable::Query}{wxdbtablequery} returns TRUE, the +When the \helpref{wxDbTable::Query}{wxdbtablequery} returns true, the database was able to successfully complete the requested query using the provided criteria. This does not mean that there are any rows in the result set, it just mean that the query was successful. @@ -740,7 +720,7 @@ set into the bound memory variables. After \helpref{wxDbTable::Query}{wxdbtableq has completed successfully, the default/current cursor is placed so it is pointing just before the first record in the result set. If the result set is empty (no rows matched the criteria), then any calls to -retrieve data from the result set will return FALSE. +retrieve data from the result set will return false. \begin{verbatim} wxString msg; @@ -762,7 +742,7 @@ in the result set. When \helpref{wxDbTable::GetNext}{wxdbtablegetnext} is called and there are no rows remaining in the result set after the current cursor position, \helpref{wxDbTable::GetNext}{wxdbtablegetnext} (as well as all the other -wxDbTable::GetXxxxx() functions) will return FALSE. +wxDbTable::GetXxxxx() functions) will return false. {\bf Close the table} @@ -832,7 +812,7 @@ this example it was stored in "DbConnectInf.Henv") have been closed, then it is safe to release the environment handle: \begin{verbatim} - DbConnectInf->FreeHenv()); + DbConnectInf->FreeHenv(); \end{verbatim} Or, if the long form of the constructor was used and the constructor was allowed @@ -848,16 +828,16 @@ connections still using the handle.} \subsection{wxODBC - Known Issues}\label{wxodbcknownissues} -As with creating wxWindows, writing the wxODBC classes was not the simple +As with creating wxWidgets, writing the wxODBC classes was not the simple task of writing an application to run on a single type of computer system. The classes need to be cross-platform for different operating systems, and they also needed to take in to account different database manufacturers and different ODBC driver manufacturers. Because of all the possible combinations of OS/database/drivers, it is impossible to say that these classes will work perfectly with datasource ABC, ODBC driver XYZ, on platform LMN. You may run -in to some incompatibilities or unsupported features when moving your +into some incompatibilities or unsupported features when moving your application from one environment to another. But that is what makes -cross-platform programming fun. It is also pinpoints one of the great +cross-platform programming fun. It also pinpoints one of the great things about open source software. It can evolve! The most common difference between different database/ODBC driver @@ -894,7 +874,7 @@ functionality as the driver can emulate. \begin{itemize}\itemsep=0pt \item Does not support the SQL\_TIMESTAMP structure \item Supports only one cursor and one connect (apparently? with Microsoft driver only?) -\item Does not automatically create the primary index if the 'keyField' param of SetColDef is TRUE. The user must create ALL indexes from their program with calls to \helpref{wxDbTable::CreateIndex}{wxdbtablecreateindex} +\item Does not automatically create the primary index if the 'keyField' param of SetColDef is true. The user must create ALL indexes from their program with calls to \helpref{wxDbTable::CreateIndex}{wxdbtablecreateindex} \item Table names can only be 8 characters long \item Column names can only be 10 characters long \item Currently cannot CREATE a dBase table - bug or limitation of the drivers used?? @@ -916,8 +896,8 @@ functionality as the driver can emulate. {\it mySQL} \begin{itemize}\itemsep=0pt \item If a column is part of the Primary Key, the column cannot be NULL. -\item Cannot support selecting for update [\helpref{wxDbTable::CanSelectForUpdate}{wxdbtablecanselectforupdate}]. Always returns FALSE. -\item Columns that are part of primary or secondary keys must be defined as being NOT NULL when they are created. Some code is added in \helpref{wxDbTable::CreateIndex}{wxdbtablecreateindex} to try to adjust the column definition if it is not defined correctly, but it is experimental (as of wxWindows v2.2.1) +\item Cannot support selecting for update [\helpref{wxDbTable::CanSelectForUpdate}{wxdbtablecanselectforupdate}]. Always returns false. +\item Columns that are part of primary or secondary keys must be defined as being NOT NULL when they are created. Some code is added in \helpref{wxDbTable::CreateIndex}{wxdbtablecreateindex} to try to adjust the column definition if it is not defined correctly, but it is experimental (as of wxWidgets v2.2.1) \item Does not support sub-queries in SQL statements \end{itemize} @@ -934,119 +914,220 @@ functionality as the driver can emulate. {\bf UNICODE with wxODBC classes} -The ODBC classes support for Unicode is yet in early experimental stage and -hasn't been tested extensively. It might work for you or it might not: please -report the bugs/problems you have encountered in the latter case. +As of v2.6 of wxWidgets, the wxODBC classes now fully support the compilation +and use of the classes in a Unicode build of wxWidgets, assuming the compiler +and OS on which the program will be compiled/run is Unicode capable. -\subsection{wxODBC - Sample Code {\tt\#}1}\label{wxodbcsamplecode1} +The one major difference in writing code that can be compiled in either +unicode or non-unicode builds that is specific to the wxODBC classes is to +use the SQL\_C\_WXCHAR datatype for string columns rather than SQL\_C\_CHAR or +SQL\_C\_WCHAR. + +\subsection{wxODBC - Sample Code}\label{wxodbcsamplecode1} Simplest example of establishing/opening a connection to an ODBC datasource, binding variables to the columns for read/write usage, opening an -existing table in the datasource, setting the query parameters +existing table in the datasource, inserting a record, setting query parameters (where/orderBy/from), querying the datasource, reading each row of the -result set, then cleaning up. +result set, deleting a record, releasing the connection, then cleaning up. -NOTE: Not all error trapping is shown here, to reduce the size of the -code and to make it more easily readable. +NOTE: Very basic error handling is shown here, to reduce the size of the +code and to make it more easily readable. The HandleError() function uses the wxDbLogExtendedErrorMsg() function for retrieving database error messages. \begin{verbatim} -wxDbConnectInf *DbConnectInf = NULL; +// ---------------------------------------------------------------------------- +// HEADERS +// ---------------------------------------------------------------------------- +#include "wx/log.h" // #included to enable output of messages only +#include "wx/dbtable.h" + +// ---------------------------------------------------------------------------- +// FUNCTION USED FOR HANDLING/DISPLAYING ERRORS +// ---------------------------------------------------------------------------- +// Very generic error handling function. +// If a connection to the database is passed in, then we retrieve all the +// database errors for the connection and add them to the displayed message +int HandleError(wxString errmsg, wxDb *pDb=NULL) +{ + // Retrieve all the error message for the errors that occurred + wxString allErrors; + if (!pDb == NULL) + // Get the database errors and append them to the error message + allErrors = wxDbLogExtendedErrorMsg(errmsg.c_str(), pDb, 0, 0); + else + allErrors = errmsg; + + // Do whatever you wish with the error message here + // wxLogDebug() is called inside wxDbLogExtendedErrorMsg() so this + // console program will show the errors in the console window, + // but these lines will show the errors in RELEASE builds also + wxFprintf(stderr, wxT("\n%s\n"), allErrors.c_str()); + fflush(stderr); + + return 1; +} -wxDb *db = NULL; // The database connection -wxDbTable *table = NULL; // The data table to access -wxChar FirstName[50+1]; // buffer for data from column "FIRST_NAME" -wxChar LastName[50+1]; // buffer for data from column "LAST_NAME" +// ---------------------------------------------------------------------------- +// entry point +// ---------------------------------------------------------------------------- +int main(int argc, char **argv) +{ +wxDbConnectInf *DbConnectInf = NULL; // DB connection information -bool errorOccured = FALSE; +wxDb *db = NULL; // Database connection -const wxChar tableName[] = "CONTACTS"; -const UWORD numTableColumns = 2; // Number of bound columns +wxDbTable *table = NULL; // Data table to access +const wxChar tableName[] = wxT("USERS"); // Name of database table +const UWORD numTableColumns = 2; // Number table columns +wxChar FirstName[50+1]; // column data: "FIRST_NAME" +wxChar LastName[50+1]; // column data: "LAST_NAME" -FirstName[0] = 0; -LastName[0] = 0; +wxString msg; // Used for display messages -DbConnectInf = new wxDbConnectInf(NULL,"MyDSN","MyUserName", "MyPassword"); +// ----------------------------------------------------------------------- +// DEFINE THE CONNECTION HANDLE FOR THE DATABASE +// ----------------------------------------------------------------------- +DbConnectInf = new wxDbConnectInf(NULL, + wxT("CONTACTS-SqlServer"), + wxT("sa"), + wxT("abk")); +// Error checking.... if (!DbConnectInf || !DbConnectInf->GetHenv()) { - wxMessageBox("Unable to allocate an ODBC environment handle", - "DB CONNECTION ERROR", wxOK | wxICON_EXCLAMATION); - return; -} + return HandleError(wxT("DB ENV ERROR: Cannot allocate ODBC env handle")); +} + -// Get a database connection from the cached connections +// ----------------------------------------------------------------------- +// GET A DATABASE CONNECTION +// ----------------------------------------------------------------------- db = wxDbGetConnection(DbConnectInf); -// Create the table connection -table = new wxDbTable(db, tableName, numTableColumns, "", - !wxDB_QUERY_ONLY, ""); +if (!db) +{ + return HandleError(wxT("CONNECTION ERROR - Cannot get DB connection")); +} + +// ----------------------------------------------------------------------- +// DEFINE THE TABLE, AND THE COLUMNS THAT WILL BE ACCESSED +// ----------------------------------------------------------------------- +table = new wxDbTable(db, tableName, numTableColumns, wxT(""), + !wxDB_QUERY_ONLY, wxT("")); // // Bind the columns that you wish to retrieve. Note that there must be -// 'numTableColumns' calls to SetColDefs(), to match the wxDbTable definition +// 'numTableColumns' calls to SetColDefs(), to match the wxDbTable def // // Not all columns need to be bound, only columns whose values are to be // returned back to the client. // -table->SetColDefs(0, "FIRST_NAME", DB_DATA_TYPE_VARCHAR, FirstName, - SQL_C_CHAR, sizeof(name), TRUE, TRUE); -table->SetColDefs(1, "LAST_NAME", DB_DATA_TYPE_VARCHAR, LastName, - SQL_C_CHAR, sizeof(LastName), TRUE, TRUE); +table->SetColDefs(0, wxT("FIRST_NAME"), DB_DATA_TYPE_VARCHAR, FirstName, + SQL_C_WXCHAR, sizeof(FirstName), true, true); +table->SetColDefs(1, wxT("LAST_NAME"), DB_DATA_TYPE_VARCHAR, LastName, + SQL_C_WXCHAR, sizeof(LastName), true, true); -// Open the table for access -table->Open(); -// Set the WHERE clause to limit the result set to only -// return all rows that have a value of 'GEORGE' in the -// FIRST_NAME column of the table. -table->SetWhereClause("FIRST_NAME = 'GEORGE'"); +// ----------------------------------------------------------------------- +// CREATE (or RECREATE) THE TABLE IN THE DATABASE +// ----------------------------------------------------------------------- +if (!table->CreateTable(true)) //NOTE: No CommitTrans is required +{ + return HandleError(wxT("TABLE CREATION ERROR: "), table->GetDb()); +} + + +// ----------------------------------------------------------------------- +// OPEN THE TABLE FOR ACCESS +// ----------------------------------------------------------------------- +if (!table->Open()) +{ + return HandleError(wxT("TABLE OPEN ERROR: "), table->GetDb()); +} + + +// ----------------------------------------------------------------------- +// INSERT A NEW ROW INTO THE TABLE +// ----------------------------------------------------------------------- +wxStrcpy(FirstName, wxT("JULIAN")); +wxStrcpy(LastName, wxT("SMART")); +if (!table->Insert()) +{ + return HandleError(wxT("INSERTION ERROR: "), table->GetDb()); +} + +// Must commit the insert to write the data to the DB +table->GetDb()->CommitTrans(); + + +// ----------------------------------------------------------------------- +// RETRIEVE ROWS FROM THE TABLE BASED ON SUPPLIED CRITERIA +// ----------------------------------------------------------------------- +// Set the WHERE clause to limit the result set to return +// all rows that have a value of 'JULIAN' in the FIRST_NAME +// column of the table. +table->SetWhereClause(wxT("FIRST_NAME = 'JULIAN'")); // Result set will be sorted in ascending alphabetical // order on the data in the 'LAST_NAME' column of each row -table->SetOrderByClause("LAST_NAME"); +table->SetOrderByClause(wxT("LAST_NAME")); // No other tables (joins) are used for this query -table->SetFromClause(""); +table->SetFromClause(wxT("")); // Instruct the datasource to perform a query based on the // criteria specified above in the where/orderBy/from clauses. if (!table->Query()) { - wxMessageBox("Error on Query()","ERROR!", - wxOK | wxICON_EXCLAMATION); - errorOccured = TRUE; + return HandleError(wxT("QUERY ERROR: "), table->GetDb()); } -wxString msg; - -// Start and continue reading every record in the table -// displaying info about each record read. +// Loop through all rows matching the query criteria until +// there are no more records to read while (table->GetNext()) { - msg.Printf("Row #%lu -- First Name : %s Last Name is %s", - table->GetRowNum(), FirstName, LastName); - wxMessageBox(msg, "Data", wxOK | wxICON_INFORMATION, NULL); + msg.Printf(wxT("Row #%lu -- First Name : %s Last Name is %s"), + table->GetRowNum(), FirstName, LastName); + + // Code to display 'msg' here + wxLogMessage(wxT("\n%s\n"), msg.c_str()); } -// If the wxDbTable instance was successfully created -// then delete it as I am done with it now. -if (table) + +// ----------------------------------------------------------------------- +// DELETE A ROW FROM THE TABLE +// ----------------------------------------------------------------------- +// Select the row which has FIRST_NAME of 'JULIAN' and LAST_NAME +// of 'SMART', then delete the retrieved row +// +if (!table->DeleteWhere(wxT("FIRST_NAME = 'JULIAN' and LAST_NAME = 'SMART'"))) { - delete table; - table = NULL; + return HandleError(wxT("DELETION ERROR: "), table->GetDb()); } + +// Must commit the deletion to the database +table->GetDb()->CommitTrans(); -// If we have a valid wxDb instance, then free the connection + +// ----------------------------------------------------------------------- +// TAKE CARE OF THE ODBC CLASS INSTANCES THAT WERE BEING USED +// ----------------------------------------------------------------------- +// If the wxDbTable instance was successfully created +// then delete it as we are done with it now. +wxDELETE(table); + +// Free the cached connection // (meaning release it back in to the cache of datasource // connections) for the next time a call to wxDbGetConnection() // is made. -if (db) -{ - wxDbFreeConnection(db); - db = NULL; -} +wxDbFreeConnection(db); +db = NULL; + +// ----------------------------------------------------------------------- +// CLEANUP BEFORE EXITING APP +// ----------------------------------------------------------------------- // The program is now ending, so we need to close // any cached connections that are still being // maintained. @@ -1054,198 +1135,16 @@ wxDbCloseConnections(); // Release the environment handle that was created // for use with the ODBC datasource connections -delete DbConnectInf; +wxDELETE(DbConnectInf); -\end{verbatim} - -\subsection{wxDatabase ODBC class overview [DEPRECATED]}\label{oldwxodbcoverview} - -Classes: \helpref{wxDatabase}{wxdatabase}, \helpref{wxRecordSet}{wxrecordset}, \helpref{wxQueryCol}{wxquerycol}, -\rtfsp\helpref{wxQueryField}{wxqueryfield} - -\normalboxd{The more sophisticated wxODBC classes (wxDb/wxDbTable) are the -recommended classes for doing database/ODBC work with wxWindows. These new -classes replace the wxWindows v1.6x classes wxDatabase. - -Documentation for the old wxDatabase class and its associated classes is still -included in the class documentation and in this overview section, but support -for these old classes has been phased out, and all future development work -is being done solely on the new wxDb/wxDbTable classes.} - -wxWindows provides a set of classes for accessing a subset of Microsoft's ODBC (Open Database Connectivity) -product. Currently, this wrapper is available under MS Windows only, although -ODBC may appear on other platforms, and a generic or product-specific SQL emulator for the ODBC -classes may be provided in wxWindows at a later date. - -ODBC presents a unified API (Application Programmer's Interface) to a -wide variety of databases, by interfacing indirectly to each database or -file via an ODBC driver. The language for most of the database -operations is SQL, so you need to learn a small amount of SQL as well as -the wxWindows ODBC wrapper API. Even though the databases may not be -SQL-based, the ODBC drivers translate SQL into appropriate operations -for the database or file: even text files have rudimentary ODBC support, -along with dBASE, Access, Excel and other file formats. - -The run-time files for ODBC are bundled with many existing database -packages, including MS Office. The required header files, sql.h and -sqlext.h, are bundled with several compilers including MS VC++ and -Watcom C++. The only other way to obtain these header files is from the -ODBC SDK, which is only available with the MS Developer Network CD-ROMs --- at great expense. If you have odbc.dll, you can make the required -import library odbc.lib using the tool `implib'. You need to have odbc.lib -in your compiler library path. - -The minimum you need to distribute with your application is odbc.dll, which must -go in the Windows system directory. For the application to function correctly, -ODBC drivers must be installed on the user's machine. If you do not use the database -classes, odbc.dll will be loaded but not called (so ODBC does not need to be -setup fully if no ODBC calls will be made). - -A sample is distributed with wxWindows in {\tt samples/odbc}. You will need to install -the sample dbf file as a data source using the ODBC setup utility, available from -the control panel if ODBC has been fully installed. - -\subsection{Procedures for writing an ODBC application using wxDatabase [DEPRECATED]} - -You first need to create a wxDatabase object. If you want to get information -from the ODBC manager instead of from a particular database (for example -using \helpref{wxRecordSet::GetDataSources}{wxrecordsetgetdatasources}), then you -do not need to call \helpref{wxDatabase::Open}{wxdatabaseopen}. -If you do wish to connect to a datasource, then call wxDatabase::Open. -You can reuse your wxDatabase object, calling wxDatabase::Close and wxDatabase::Open -multiple times. - -Then, create a wxRecordSet object for retrieving or sending information. -For ODBC manager information retrieval, you can create it as a dynaset (retrieve the -information as needed) or a snapshot (get all the data at once). -If you are going to call \helpref{wxRecordSet::ExecuteSQL}{wxrecordsetexecutesql}, you need to create it as a snapshot. -Dynaset mode is not yet implemented for user data. - -Having called a function such as wxRecordSet::ExecuteSQL or -wxRecordSet::GetDataSources, you may have a number of records -associated with the recordset, if appropriate to the operation. You can -now retrieve information such as the number of records retrieved and the -actual data itself. Use \helpref{wxRecordSet::GetFieldData}{wxrecordsetgetfielddata} or -\helpref{wxRecordSet::GetFieldDataPtr}{wxrecordsetgetfielddataptr} to get the data or a pointer to it, passing -a column index or name. The data returned will be for the current -record. To move around the records, use \helpref{wxRecordSet::MoveNext}{wxrecordsetmovenext}, -\rtfsp\helpref{wxRecordSet::MovePrev}{wxrecordsetmoveprev} and associated functions. - -You can use the same recordset for multiple operations, or delete -the recordset and create a new one. - -Note that when you delete a wxDatabase, any associated recordsets -also get deleted, so beware of holding onto invalid pointers. - -\subsection{wxDatabase class overview [DEPRECATED]}\label{wxdatabaseoverview} - -Class: \helpref{wxDatabase}{wxdatabase} - -\wxheading{DEPRECATED} - -Use \helpref{wxDb}{wxdb} and \helpref{wxDbTable}{wxdbtable} instead. - -Every database object represents an ODBC connection. To do anything useful -with a database object you need to bind a wxRecordSet object to it. All you -can do with wxDatabase is opening/closing connections and getting some info -about it (users, passwords, and so on). - -\wxheading{See also} - -\helpref{Database classes overview}{odbcoverview} - -\subsection{wxQueryCol class overview [DEPRECATED]}\label{wxquerycoloverview} - -Class: \helpref{wxQueryCol}{wxquerycol} - -\wxheading{DEPRECATED} - -Use \helpref{wxDb}{wxdb} and \helpref{wxDbTable}{wxdbtable} instead. - -Every data column is represented by an instance of this class. -It contains the name and type of a column and a list of wxQueryFields where -the real data is stored. The links to user-defined variables are stored -here, as well. - -\wxheading{See also} - -\helpref{Database classes overview}{odbcoverview} - -\subsection{wxQueryField class overview [DEPRECATED]}\label{wxqueryfieldoverview} - -Class: \helpref{wxQueryField}{wxqueryfield} - -\wxheading{DEPRECATED} - -Use \helpref{wxDb}{wxdb} and \helpref{wxDbTable}{wxdbtable} instead. - -As every data column is represented by an instance of the class wxQueryCol, -every data item of a specific column is represented by an instance of -wxQueryField. Each column contains a list of wxQueryFields. If wxRecordSet is -of the type wxOPEN\_TYPE\_DYNASET, there will be only one field for each column, -which will be updated every time you call functions like wxRecordSet::Move -or wxRecordSet::GoTo. If wxRecordSet is of the type wxOPEN\_TYPE\_SNAPSHOT, -all data returned by an ODBC function will be loaded at once and the number -of wxQueryField instances for each column will depend on the number of records. - -\wxheading{See also} - -\helpref{Database classes overview}{odbcoverview} +wxUnusedVar(argc); // Here just to prevent compiler warnings +wxUnusedVar(argv); // Here just to prevent compiler warnings -\subsection{wxRecordSet overview [DEPRECATED]}\label{wxrecordsetoverview} - -Class: \helpref{wxRecordSet}{wxrecordset} - -\wxheading{DEPRECATED} - -Use \helpref{wxDb}{wxdb} and \helpref{wxDbTable}{wxdbtable} instead. - -Each wxRecordSet represents a database query. You can make multiple queries -at a time by using multiple wxRecordSets with a wxDatabase or you can make -your queries in sequential order using the same wxRecordSet. - -\wxheading{See also} - -\helpref{Database classes overview}{odbcoverview} - -\subsection{ODBC SQL data types [DEPRECATED]}\label{sqltypes} - -These are the data types supported in ODBC SQL. Note that there are other, extended level conformance -types, not currently supported in wxWindows. - -\begin{twocollist}\itemsep=0pt -\twocolitem{CHAR(n)}{A character string of fixed length {\it n}.} -\twocolitem{VARCHAR(n)}{A varying length character string of maximum length {\it n}.} -\twocolitem{LONG VARCHAR(n)}{A varying length character string: equivalent to VARCHAR for the purposes -of ODBC.} -\twocolitem{DECIMAL(p, s)}{An exact numeric of precision {\it p} and scale {\it s}.} -\twocolitem{NUMERIC(p, s)}{Same as DECIMAL.} -\twocolitem{SMALLINT}{A 2 byte integer.} -\twocolitem{INTEGER}{A 4 byte integer.} -\twocolitem{REAL}{A 4 byte floating point number.} -\twocolitem{FLOAT}{An 8 byte floating point number.} -\twocolitem{DOUBLE PRECISION}{Same as FLOAT.} -\end{twocollist} - -These data types correspond to the following ODBC identifiers: - -\begin{twocollist}\itemsep=0pt -\twocolitem{SQL\_CHAR}{A character string of fixed length.} -\twocolitem{SQL\_VARCHAR}{A varying length character string.} -\twocolitem{SQL\_DECIMAL}{An exact numeric.} -\twocolitem{SQL\_NUMERIC}{Same as SQL\_DECIMAL.} -\twocolitem{SQL\_SMALLINT}{A 2 byte integer.} -\twocolitem{SQL\_INTEGER}{A 4 byte integer.} -\twocolitem{SQL\_REAL}{A 4 byte floating point number.} -\twocolitem{SQL\_FLOAT}{An 8 byte floating point number.} -\twocolitem{SQL\_DOUBLE}{Same as SQL\_FLOAT.} -\end{twocollist} - -\wxheading{See also} - -\helpref{Database classes overview}{odbcoverview} +return 0; +} +\end{verbatim} -\subsection{A selection of SQL commands [DEPRECATED]}\label{sqlcommands} +\subsection{A selection of SQL commands}\label{sqlcommands} The following is a very brief description of some common SQL commands, with examples. @@ -1254,7 +1153,7 @@ examples. \helpref{Database classes overview}{odbcoverview} -\subsubsection{Create} +\subsubsection{Create}\label{odbccreateexample} Creates a table. @@ -1270,7 +1169,7 @@ CREATE TABLE Book ) \end{verbatim} -\subsubsection{Insert} +\subsubsection{Insert}\label{odbcinsertexample} Inserts records into a table. @@ -1282,7 +1181,7 @@ INSERT INTO Book VALUES(5, 'HR', 'The Lark Ascending') \end{verbatim} -\subsubsection{Select} +\subsubsection{Select}\label{odbcselectexample} The Select operation retrieves rows and columns from a table. The criteria for selection and the columns returned may be specified. @@ -1317,7 +1216,7 @@ descending order, add DESC after the ORDER BY Title clause. Selects records where RetailPriceAmount conforms to the WHERE expression. -\subsubsection{Update} +\subsubsection{Update}\label{odbcupdateexample} Updates records in a table.