Example usage for java.sql PreparedStatement getMetaData

Introduction

In this page you can find the example usage for java.sql PreparedStatement getMetaData.

Prototype

ResultSetMetaData getMetaData() throws SQLException;

Source Link

Document

Retrieves a ResultSetMetaData object that contains information about the columns of the ResultSet object that will be returned when this PreparedStatement object is executed.

Usage

From source file:org.pentaho.di.core.database.Database.java

public RowMetaInterface getQueryFields(String sql, boolean param, RowMetaInterface inform, Object[] data)
        throws KettleDatabaseException {
    RowMetaInterface fields;// w  w  w  .j  a  v a 2  s .c  o  m
    DBCache dbcache = DBCache.getInstance();

    DBCacheEntry entry = null;

    // Check the cache first!
    //
    if (dbcache != null) {
        entry = new DBCacheEntry(databaseMeta.getName(), sql);
        fields = dbcache.get(entry);
        if (fields != null) {
            return fields;
        }
    }
    if (connection == null) {
        return null; // Cache test without connect.
    }

    // No cache entry found

    // The new method of retrieving the query fields fails on Oracle because
    // they failed to implement the getMetaData method on a prepared statement.
    // (!!!)
    // Even recent drivers like 10.2 fail because of it.
    //
    // There might be other databases that don't support it (we have no
    // knowledge of this at the time of writing).
    // If we discover other RDBMSs, we will create an interface for it.
    // For now, we just try to get the field layout on the re-bound in the
    // exception block below.
    //
    if (databaseMeta.supportsPreparedStatementMetadataRetrieval()) {
        // On with the regular program.
        //

        PreparedStatement preparedStatement = null;
        try {
            preparedStatement = connection.prepareStatement(databaseMeta.stripCR(sql),
                    ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
            preparedStatement.setMaxRows(1);
            ResultSetMetaData rsmd = preparedStatement.getMetaData();
            fields = getRowInfo(rsmd, false, false);
        } catch (Exception e) {
            fields = getQueryFieldsFallback(sql, param, inform, data);
        } finally {
            if (preparedStatement != null) {
                try {
                    preparedStatement.close();
                } catch (SQLException e) {
                    throw new KettleDatabaseException(
                            "Unable to close prepared statement after determining SQL layout", e);
                }
            }
        }
    } else {
        /*
         * databaseMeta.getDatabaseType()==DatabaseMeta.TYPE_DATABASE_SYBASEIQ ) {
         */
        fields = getQueryFieldsFallback(sql, param, inform, data);
    }

    // Store in cache!!
    if (dbcache != null && entry != null) {
        if (fields != null) {
            dbcache.put(entry, fields);
        }
    }

    return fields;
}

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From source file:org.pentaho.di.core.database.Database.java

private RowMetaInterface getQueryFieldsFallback(String sql, boolean param, RowMetaInterface inform,
        Object[] data) throws KettleDatabaseException {
    RowMetaInterface fields;/*from w ww.  java 2  s. com*/

    try {
        if ((inform == null
                // Hack for MSSQL jtds 1.2 when using xxx NOT IN yyy we have to use a
                // prepared statement (see BugID 3214)
                && (databaseMeta.getDatabaseInterface() instanceof MSSQLServerDatabaseMeta
                        || databaseMeta.getDatabaseInterface() instanceof KettleDatabaseMeta))
                || databaseMeta.getDatabaseInterface().supportsResultSetMetadataRetrievalOnly()) {
            sel_stmt = connection.createStatement(ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);

            if (databaseMeta.isFetchSizeSupported() && sel_stmt.getMaxRows() >= 1) {
                if (databaseMeta.getDatabaseInterface() instanceof MySQLDatabaseMeta) {
                    sel_stmt.setFetchSize(Integer.MIN_VALUE);
                } else {
                    sel_stmt.setFetchSize(1);
                }
            }
            if (databaseMeta.supportsSetMaxRows()) {
                sel_stmt.setMaxRows(1);
            }

            ResultSet r = sel_stmt.executeQuery(databaseMeta.stripCR(sql));
            fields = getRowInfo(r.getMetaData(), false, false);
            r.close();
            sel_stmt.close();
            sel_stmt = null;
        } else {
            PreparedStatement ps = connection.prepareStatement(databaseMeta.stripCR(sql));
            if (param) {
                RowMetaInterface par = inform;

                if (par == null || par.isEmpty()) {
                    par = getParameterMetaData(ps);
                }

                if (par == null || par.isEmpty()) {
                    par = getParameterMetaData(sql, inform, data);
                }

                setValues(par, data, ps);
            }
            ResultSet r = ps.executeQuery();
            fields = getRowInfo(ps.getMetaData(), false, false);
            r.close();
            ps.close();
        }
    } catch (Exception ex) {
        throw new KettleDatabaseException("Couldn't get field info from [" + sql + "]" + Const.CR, ex);
    }

    return fields;
}

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