Release 10.1A: OpenEdge Development:
Java Open Clients

Getting meta data for OUTPUT TABLE and TABLE-HANDLE parameters

You can obtain schema information for a standard ResultSet object by accessing the java.sql.ResultSetMetaData object returned by the getMetaData() method on the ResultSet. This ResultSetMetaData object allows you to access the schema information for each column in the ResultSet.

The com.progress.open4gl.ProResultSetMetaData interface is an OpenEdge extension of the java.sql.ResultSetMetaData interface. The extensions in ProResultSetMetaData access the schema information for the ProResultSet object viewed as temp-table fields, using the array model. To use these extensions, you must cast the ResultSetMetaData object returned from getMetaData() as a ProResultSetMetaData object:

// In this code, resultOut is a ProResultSet obtained as an output parameter. java.sql.ResultSetMetaData metaData = resultOut.getMetaData(); // To access the extended set of methods the application does: com.progress.open4gl.ProResultSetMetaData proMetaData =    (com.progress.open4gl.ProResultSetMetaData)metaData; // Now we use proMetaData to access the ProResultSetMetaData extensions

The rest of this section describes the ProResultSetMetaData methods and how they allow you to view a ProResultSet object both as standard ResultSet columns and temp-table fields, using the array model.

Standard methods in the ProResultSetMetaData class

The ProResultSetMetaData class has the following public methods:

These methods are part of the standard java.sql.ResultSetMetaData interface and are useful if the client wants to write standard code that could access any JDBC ResultSet:

int getColumnCount() throws ProSQLException

String getColumnName(int columnNum) throws ProSQLException

int getColumnType(int columnNum) throws ProSQLException

The getColumnType() method returns an int constant for the standard SQL types as shown in Table C–7. The SQL data type column in the table shows the type names as specified by the java.sql.Types class:

String getColumnTypeName(int columnNum) throws ProSQLException

The getColumnTypeName() method returns the corresponding Progress data type names shown in Table C–7 under Progress data type.

Table C–7: Progress to SQL data type mappings 

Progress data type	SQL data type
BLOB	BLOB
CHARACTER	LONGVARCHAR
CLOB	CLOB
COM-HANDLE	BIGINT
DATE	DATE
DATETIME DATETIME-TZ	TIMESTAMP
DECIMAL	DECIMAL
INTEGER	INTEGER
LOGICAL	BIT
RAW	VARBINARY
RECID	BIGINT
ROWID	VARBINARY
WIDGET-HANDLE	BIGINT

ProResultSetMetaData class extension to java.sql.ResultSetMetaData

All the methods based directly on the standard java.sql.ResultSetMetaData class view the temp-table using the standard SQL flat column model (columns without arrays)

These methods all view the columns as fields with arrays:

The following methods allow you to see the data type of each ResultSet column as Progress and Java types:

int getColumnProType(int columnNum) throws ProSQLException

This returns one of the constant values accessible from com.progress.open4gl.Parameter:

String getColumnJavaTypeName(int columnNum) throws ProSQLException

getColumnJavaTypeName() returns the name of the Java class to which each Progress data type maps. For information on these mappings, see Table C–1.

For more information, see the information on specifying data type meta data for temp-tables in Chapter 4, " Passing Parameters."

The following methods provide access to the schema of temp-table parameters that contain array fields, viewed from an OpenEdge viewpoint:

int getFieldCount() throws ProSQLException

String getFieldName(int fieldNum) throws ProSQLException

int getFieldExtent(int fieldNum) throws ProSQLException

int getFieldProType(int fieldNum) throws ProSQLException

String getFieldJavaTypeName(int fieldNum) throws ProSQLException

String getFieldTypeName(int fieldNum) throws ProSQLException

The Progress-oriented methods, which view the temp-table using the Progress array field model (fields that can include arrays), have prototypes that refer to Field or field. For more information on the relationship between ResultSet columns and Progress array fields, see the "Accessing temp-table array fields" section.

Although you can access the data using either the SQL or Progress model, both provide equivalent functionality. Table C–8 shows the correspondence between the ProResultSetMetaData methods.

Table C–8: Comparing some array and flat model methods  

This method returns the same set of values ...	As this method ...
getFieldName()	getColumnName()
getFieldProType()	getColumnProType()
getFieldJavaTypeName()	getColumnJavaTypeName()
getFieldTypeName()	getColumnTypeName()