66 Using ArcView Database Access

An SDELog represents a logfile, which is a file on the SDE server that records a list of shapes in a spatial column. You can use an SDELog to record which shapes satisfy a query by setting the query’s destination to be an SDELog object. Similarly, if you have an SDELog, you can retrieve the rows containing its shapes by setting the query’s source to the SDELog. You change a spatial query’s source and destination using the SetSrcDest request. ArcView uses logfiles to make selections work for database themes.

The ODBC interface objects

ODBCTable ODBCConnection ODBCQueryDef ODBCRecordSet

ODBCDiagnostic

The objects for the ODBC database interface include the subclasses ODBCConnection, ODBCQueryDef, ODBCRecordSet, ODBCTable, and an additional class ODBCDiagnostic. The new class is provided to support error reporting from ODBC.

An ODBCConnection defines the communication layer between ArcView and the database. In order to use the ODBC database interface you must be using a Windows version of ArcView and have ODBC installed with the appropriate database drivers.

If you use the user interface to make a connection, you must first create an ODBC data source using the ODBC Data Source Administrator. An ODBC data source includes the information needed by the driver to connect to your database.

If you use Avenue to connect to the database, you can choose to provide all of the needed connection information with the request or to use an already existing data source. There are three connection requests available, each allowing you to provide the connection information in a different way.

The Make request takes a data source name, the name of the database, the user name and the password. Depending on the database, the database name, user name and password arguments may not be applicable. For SYBASE and SQL Server, data is organized in databases so the database name argument is relevant. There is no corresponding concept

in an Oracle database so the argument is of not relevant. When an argument is not applicable or is not required, provide an empty string “”.

The MakeWithConnStr request takes a formatted ODBC connection string. You can format the string to use either an existing machine data source, an existing file data source or provide all of the connection information without a data source. Refer to you ODBC driver documentation to find out how to format this string.

When the MakeWithDialog request is used, an ODBC connection dialog appears. This dialog is created by the driver and allows you to enter all the information needed to connect.

An ODBCQueryDef contains an SQL statement that can be executed on the database. You can use SQL statements that do not return data, like create table or create index, or you can use a select statement to query tables in the database. ODBCQueryDef’s defined with select statements can be used to create database tables. The SQL syntax may vary slightly depending on the driver and the database.

You can assign a SQL statement to an ODBCQueryDef using the SetSelectColumns, SetfromTables and SetWhereClause requests or the SetSQL request. You cannot use the SetSQL request in combination to the other three requests.

An ODBCTable can be created to represent any single table in the database. You can retrieve the data in the table by creating an ODBCRecordSet. With an ODBCTable, you can provide a where clause to restrict the rows that are returned by the ODBCRecordSet.

An ODBCRecordSet can be created by using an OpenRecordSet request on either an ODBCQueryDef or an ODBCTable. An ODBCRecordSet is used to read data or add, edit and delete rows from a table in the database. You can determine if you have editing privileges by using the ODBCRecordSet’s CanUpdate request. In order for an ODBCQueryDef ’s RecordSet to be editable, it must also have been created using the SetSelectColumns, SetFromTables and SetWhereClause requests and must have only one table in the FromTables list. An ODBCTable’s RecordSet will be editable as long as you have the proper permissions.

The ODBCDiagnostic class is used to retrieve the ODBC error and warning messages for a given transaction. An ODBCDiagnostic object can be created for either an ODBCConnection or an ODBCRecordSet. ODBC typically returns several messages for a transaction, even if it is successful. The ODBCDiagnosticRecord messages contain a SQL status message, the ODBC SQL state and native RDBMS Error Codes. The most severe error is always at the top of the list of messages. SQL status, SQL state and RDBMS error codes vary from database vendor to database vendor so you need to consult the RDBMS and ODBC driver documentation to interpret the information.

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C H A P T E R 5

Using Avenue to manipulate SDE objects

You can write Avenue scripts to customize the way you create database themes and database tables; to analyze the data they contain; and to add, edit, or delete the source data in the database. With Avenue, you have greater control over the Database Access objects and therefore the results. This chapter assumes that you have already worked through Chapters 2 and 4 in this book and that you know how to create and use Avenue scripts.

In this chapter, you’ll learn how to use Avenue scripts to:

•Add a database theme to a view.

•Step through a database theme’s records.

•Select features in a database theme.

•Work with selected features.

•Create and work with database tables.

•Work with selected records in database tables.

•Modify the source data.

•Use locks and transactions.

•Check for errors.

•Create new tables and spatial columns.