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Work with HPCC Systems Data in FoxPro

Load HPCC Systems data into a FoxPro database. This article includes full code and a walk-through of the process.

The CData ODBC Driver for HPCC Systems enables you to access HPCC Systems data using the ODBC standard. You can use the CData ODBC Driver for HPCC Systems to integrate HPCC Systems data into your FoxPro project. The procedure below provides a walk-through of the included code sample, which saves HPCC Systems data into tables in a FoxPro database.

Connect to HPCC Systems as an ODBC Data Source

If you have not already, first specify connection properties in an ODBC DSN (data source name). This is the last step of the driver installation. You can use the Microsoft ODBC Data Source Administrator to create and configure ODBC DSNs.

NOTE: Set the 'Map To WVarchar' connection property to FALSE (FoxPro uses the ODBC W API and returns the WCHAR for the value type).

To connect, set the following connection properties: Set URL to the machine name or IP address of the server and the port the server is running on, for example, https://server:port. The User and Password are required to authenticate to the HPCC Systems cluster specified in the URL. Note that LDAP authentication is not currently supported by our ODBC driver.

Set Version to the WsSQL Web server version. Note that if you have not already done so, you will need to install the WsSQL service on the HPCC Systems server. The WsSQL Web service is used to interact with the underlying HPCC Systems platform.

Set Cluster to the target cluster.

Connect and Transfer

To get started, add the code sample to a new project. You can execute the following command to save all tables without displaying them:

DO C:\Temp\sqldump.prg WITH "CData HPCC Source", "TESTDB", .f.

Below is the process that the program follows:

  1. Create a new FoxPro database.
  2. Open a connection to HPCC Systems data with the line below:

    m.hSQLconnection = SQLCONNECT(m.cODBCDSN)
  3. If the connection was successful, you can now retrieve the list of tables using the SQLTABLES function. The code below saves the list of tables in sys_tables.dbf:

    WAIT WINDOW "Fetching tables for data source '" + m.cODBCDSN + "'..." NOWAIT NOCLEAR m.nSQLTABLES = SQLTABLES(m.hSQLconnection) IF lUseDistinctConnections WAIT WINDOW "Closing ODBC Connection for data source '" + m.cODBCDSN + "'..." NOWAIT NOCLEAR SQLDISCONNECT(m.hSQLconnection) m.hSQLconnection = 0 * SQLCONNECT needs to be called again ENDIF IF m.nSQLTABLES > 0 * create local table containing list of tables in db COPY TO (m.cImportData + "sys_tables") USE * convert each table to DBF USE (m.cImportData + "sys_tables") ALTER TABLE DBF("sys_tables") ; ADD COLUMN records i ; ADD COLUMN dbfname m
  4. Scan over each table, saving it to a DBF file. The function ODBCtoDBF stores the table in a DBF file and then opens a grid if the lBrowse parameter is set to true: FUNCTION ODBCtoDBF (cTableName as String, cTableType as String, lBrowse as Logical, lhSQLConnection as Integer) WAIT WINDOW ; "Converting " + m.cTableType + ' "' + m.cTableName + '" to DBF...' ; NOWAIT NOCLEAR ACTIVATE SCREEN * strip characters incompatible with FoxPro out of the name of the DBF file m.cTableAlias = "" m.nTableNameLen = LEN(m.cTableName) m.nTableNameStart = 1 FOR m.nTableNameStart = 1 TO m.nTableNameLen m.cCharacter = SUBSTR(m.cTableName, m.nTableNameStart, 1) IF !ISALPHA(m.cCharacter) .and. (m.nTableNameStart = 1 .or. !ISDIGIT(m.cCharacter)) m.cTableAlias = m.cTableAlias + "_" ELSE m.cTableAlias = m.cTableAlias + m.cCharacter ENDIF ENDFOR m.cFromTable = m.cTableName m.cTempViewAlias = m.cTableType + "_" + m.cTableAlias LOCAL loException as Exception LOCAL lnResultSets TRY * run query m.lnResultSets = SQLEXEC(m.lhSQLConnection, ; "SELECT * FROM " + m.cFromTable, ; m.cTempViewAlias, ; aSQLResult) IF m.lnResultSets#1 SET STEP ON ENDIF ACTIVATE SCREEN CATCH TO m.loException ACTIVATE SCREEN ? "Error opening " + m.cTempViewAlias + ":" ? m.loException.Message ? m.loException.Details ENDTRY IF !USED(m.cTempViewAlias) RETURN ENDIF * copy records from view cursor to disk SELECT * FROM (m.cTempViewAlias) ; INTO TABLE (m.cImportData + m.cTableAlias) IF USED(m.cTableAlias) ACTIVATE SCREEN FLUSH && flush the buffer to write the data to disk IF m.lBrowse * pop the table up on screen SELECT (m.cTableAlias) BROWSE NORMAL NOMODIFY NOWAIT ACTIVATE SCREEN ELSE * close on-disk table for now USE IN (m.cTableAlias) ACTIVATE SCREEN ENDIF ENDIF IF USED(m.cTempViewAlias) USE IN &cTempViewAlias && close SQL view ACTIVATE SCREEN ENDIF WAIT CLEAR ENDFUNC
  5. You can now save tables of HPCC Systems data as DBF files.

Below is the full code, in FoxPro 9 syntax:

PARAMETERS cODBCDSN, cDatabaseName, lBrowseAfterConvert * cODBCDSN The ODBC data source name, used for the name of the folder where the DBF tables are stored. * cDatabaseName The name of the FoxPro database to use. This database is created if it does not exist. The default is DATABASE_NAME. * * lBrowseAfterConvert If ".t." display each table with the BROWSE command after importing it. If ".f." close each table before moving on to the next one. #define ODBC_DATASOURCE "DataSourceName" #define DATABASE_NAME "odbcdata" m.m_tpath = ".\" && root directory for data ON ERROR SET SAFETY OFF IF VARTYPE(m.cODBCDSN)#"C" .or. EMPTY(m.cODBCDSN) m.cODBCDSN = ODBC_DATASOURCE ENDIF IF VARTYPE(m.cDatabaseName)#"C" .or. EMPTY(m.cDatabaseName) m.cDatabaseName = DATABASE_NAME ENDIF m.cImportData = m.cODBCDSN + "\" CLOSE TABLES ALL CLOSE DATABASES ALL IF !DIRECTORY(m.cImportData) MKDIR (m.cImportData) ENDIF CREATE DATABASE (m.cDatabaseName) CREATE CONNECTION (m.cDatabaseName) DATASOURCE (m.cODBCDSN) DATABASE (m.cDatabaseName) WAIT WINDOW "Opening ODBC Connection for data source '" + m.cODBCDSN + "'..." NOWAIT NOCLEAR m.hSQLconnection = SQLCONNECT(m.cODBCDSN) IF m.hSQLconnection > 0 * Connection successful; get list of tables WAIT WINDOW "Fetching tables for data source '" + m.cODBCDSN + "'..." NOWAIT NOCLEAR m.nSQLTABLES = SQLTABLES(m.hSQLconnection) IF m.nSQLTABLES > 0 * Create local table containing list of tables in db COPY TO (m.cImportData + "sys_tables") USE * Convert each table to DBF USE (m.cImportData + "sys_tables") ALTER TABLE DBF("sys_tables") ; ADD COLUMN records i ; ADD COLUMN dbfname m SCAN m.cCurrentTable = TRIM(sys_tables.table_name) m.cCurrentTableType = TRIM(sys_tables.table_type) && Valid values are "SYSTEMTABLE", "TABLE", and "VIEW". IF m.cCurrentTableType = "TABLE" or m.cCurrentTableType = "VIEW" ODBCtoDBF(m.cCurrentTable, m.cCurrentTableType, m.lBrowseAfterConvert, m.hSQLConnection) ELSE ACTIVATE SCREEN ? "ERROR:", m.cCurrentTable, "Couldn't open ODBC connection." =MESSAGEBOX("couldn't open data source " + m.cODBCDSN + " for table " + m.cCurrentTable + ".") ENDIF ENDSCAN BROWSE NORMAL NOWAIT ELSE =MESSAGEBOX("No tables found in data source " + m.cODBCDSN + ".") SET STEP ON ENDIF SQLDISCONNECT(m.hSQLconnection) ELSE =MESSAGEBOX("Could not open data source " + m.cODBCDSN + ".") SET STEP ON ENDIF FUNCTION ODBCtoDBF (cTableName as String, cTableType as String, lBrowse as Logical, lhSQLConnection as Integer) WAIT WINDOW ; "Converting " + m.cTableType + ' "' + m.cTableName + '" to DBF...' ; NOWAIT NOCLEAR ACTIVATE SCREEN * Strip characters incompatible with FoxPro out of the name of the DBF file m.cTableAlias = "" m.nTableNameLen = LEN(m.cTableName) m.nTableNameStart = 1 FOR m.nTableNameStart = 1 TO m.nTableNameLen m.cCharacter = SUBSTR(m.cTableName, m.nTableNameStart, 1) IF !ISALPHA(m.cCharacter) .and. (m.nTableNameStart = 1 .or. !ISDIGIT(m.cCharacter)) m.cTableAlias = m.cTableAlias + "_" ELSE m.cTableAlias = m.cTableAlias + m.cCharacter ENDIF ENDFOR m.cFromTable = m.cTableName m.cTempViewAlias = m.cTableType + "_" + m.cTableAlias LOCAL loException as Exception LOCAL lnResultSets TRY * Run query m.lnResultSets = SQLEXEC(m.lhSQLConnection, ; "SELECT * FROM " + m.cFromTable, ; m.cTempViewAlias, ; aSQLResult) IF m.lnResultSets#1 SET STEP ON ENDIF ACTIVATE SCREEN CATCH TO m.loException ACTIVATE SCREEN ? "Error opening " + m.cTempViewAlias + ":" ? m.loException.Message ? m.loException.Details ENDTRY IF !USED(m.cTempViewAlias) RETURN ENDIF * Copy records from view cursor to disk SELECT * FROM (m.cTempViewAlias) ; INTO TABLE (m.cImportData + m.cTableAlias) IF USED(m.cTableAlias) ACTIVATE SCREEN FLUSH && Flush the buffer to write the data to disk IF m.lBrowse * Display the table on screen SELECT (m.cTableAlias) BROWSE NORMAL NOMODIFY NOWAIT ACTIVATE SCREEN ELSE * Close on-disk table USE IN (m.cTableAlias) ACTIVATE SCREEN ENDIF ENDIF IF USED(m.cTempViewAlias) USE IN &cTempViewAlias && Close SQL view ACTIVATE SCREEN ENDIF WAIT CLEAR ENDFUNC