Examples of org.apache.metamodel.query.SelectItem

org.apache.metamodel.query.SelectItem
Represents a SELECT item. SelectItems can take different forms:
- column SELECTs (selects a column from a table)
- column function SELECTs (aggregates the values of a column)
- expression SELECTs (retrieves data based on an expression (only supported for JDBC datastores)
- expression function SELECTs (retrieves databased on a function and an expression, only COUNT(*) is supported for non-JDBC datastores))
- SELECTs from subqueries (works just like column selects, but in stead of pointing to a column, it retrieves data from the select item of a subquery)
@see SelectClause

        _rowDeletionInterceptors = rowDeletionInterceptors;
    }


    @Override
    public FilterBuilder<RowDeletionBuilder> where(Column column) {
        final SelectItem selectItem = new SelectItem(column);
        return new AbstractFilterBuilder<RowDeletionBuilder>(selectItem) {
            @Override
            protected RowDeletionBuilder applyFilter(FilterItem filter) {
                return where(filter);
            }

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            final FromItem fromItem = query.getFromClause().getItem(0);
            final Table table = fromItem.getTable();
            if (table != null) {
                // check for approximate SELECT COUNT(*) queries
                if (selectItems.size() == 1) {
                    final SelectItem selectItem = query.getSelectClause().getItem(0);
                    if (SelectItem.isCountAllItem(selectItem)) {
                        final boolean functionApproximationAllowed = selectItem.isFunctionApproximationAllowed();
                        if (isMainSchemaTable(table)) {
                            logger.debug("Query is a COUNT query with {} where items. Trying executeCountQuery(...)",
                                    whereItems.size());
                            final Number count = executeCountQuery(table, whereItems, functionApproximationAllowed);
                            if (count == null) {
                                logger.debug("DataContext did not return any count query results. Proceeding with manual counting.");
                            } else {
                                List<Row> data = new ArrayList<Row>(1);
                                final DataSetHeader header = new SimpleDataSetHeader(new SelectItem[] { selectItem });
                                data.add(new DefaultRow(header, new Object[] { count }));
                                return new InMemoryDataSet(header, data);
                            }
                        }
                    }
                }


                // check for lookup query by primary key
                if (whereItems.size() == 1) {
                    final FilterItem whereItem = whereItems.get(0);
                    final SelectItem selectItem = whereItem.getSelectItem();
                    if (!whereItem.isCompoundFilter() && selectItem != null && selectItem.getColumn() != null) {
                        final Column column = selectItem.getColumn();
                        if (column.isPrimaryKey() && whereItem.getOperator() == OperatorType.EQUALS_TO) {
                            logger.debug("Query is a primary key lookup query. Trying executePrimaryKeyLookupQuery(...)");
                            if (table != null) {
                                if (isMainSchemaTable(table)) {
                                    final Object operand = whereItem.getOperand();

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            // queries)
            Column[] columns = table.getColumns();
            if (columns.length == 0) {
                logger.warn("Queried table has no columns: {}", table);
            } else {
                selectItems.add(new SelectItem(columns[0]));
            }
        }


        if (maxRows == 0) {
            return new EmptyDataSet(selectItems);

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    public Row getRow() {
        final int size = getHeader().size();
        final Object[] values = new Object[size];


        for (int i = 0; i < values.length; i++) {
            final SelectItem selectItem = getHeader().getSelectItem(i);
            final String column = selectItem.getColumn().getName();
            values[i] = _pojoTable.getValue(column, _next);
        }


        return new DefaultRow(getHeader(), values);
    }

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        return _whereItems;
    }


    @Override
    public FilterBuilder<RowDeletionBuilder> where(Column column) {
        SelectItem selectItem = new SelectItem(column);
        return new AbstractFilterBuilder<RowDeletionBuilder>(selectItem) {
            @Override
            protected RowDeletionBuilder applyFilter(FilterItem filter) {
                return where(filter);
            }

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        callback.deleteFrom(_table).where(_whereItems).execute();
    }


    @Override
    public FilterBuilder<DeleteFrom> where(Column column) {
        SelectItem selectItem = new SelectItem(column);
        return new AbstractFilterBuilder<DeleteFrom>(selectItem) {
            @Override
            protected DeleteFrom applyFilter(FilterItem filter) {
                return where(filter);
            }

View Full Code Here


    @Override
    public RowInsertionBuilder like(Row row) {
        SelectItem[] selectItems = row.getSelectItems();
        for (int i = 0; i < selectItems.length; i++) {
            SelectItem selectItem = selectItems[i];
            Column column = selectItem.getColumn();
            if (column != null) {
                if (_table == column.getTable()) {
                    value(column, row.getValue(i));
                } else {
                    value(column.getName(), row.getValue(i));

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    public void testApproximatedCountSmallFile() throws Exception {
        DataContext dc = new CsvDataContext(new File("src/test/resources/csv_people.csv"));


        Table table = dc.getDefaultSchema().getTables()[0];
        Query q = dc.query().from(table).selectCount().toQuery();
        SelectItem selectItem = q.getSelectClause().getItem(0);
        selectItem.setFunctionApproximationAllowed(true);


        DataSet ds = dc.executeQuery(q);
        assertTrue(ds.next());
        Object[] values = ds.getRow().getValues();
        assertEquals(1, values.length);

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        QueryPostprocessDataContext dc = new CsvDataContext(file);
        Table table = dc.getDefaultSchema().getTableByName("csv_people.csv");


        Query q = new Query();
        q.from(table);
        q.where(new FilterItem(new SelectItem(table.getColumnByName("id")), OperatorType.EQUALS_TO, 1));
        q.select(table.getColumnByName("name"));
        DataSet data = dc.executeQuery(q);
        assertTrue(data.next());
        assertEquals("Row[values=[mike]]", data.getRow().toString());
        assertFalse(data.next());

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        Table table = dc.getDefaultSchema().getTableByName("csv_people.csv");


        Query q = new Query();
        q.from(table);
        q.groupBy(table.getColumnByName("gender"));
        q.select(new SelectItem(table.getColumnByName("gender")),
                new SelectItem(FunctionType.MAX, table.getColumnByName("age")),
                new SelectItem(FunctionType.MIN, table.getColumnByName("age")), new SelectItem(FunctionType.COUNT, "*",
                        "total"), new SelectItem(FunctionType.MIN, table.getColumnByName("id")).setAlias("firstId"));
        DataSet data = dc.executeQuery(q);
        assertEquals(
                "[csv_people.csv.gender, MAX(csv_people.csv.age), MIN(csv_people.csv.age), COUNT(*) AS total, MIN(csv_people.csv.id) AS firstId]",
                Arrays.toString(data.getSelectItems()));

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org.apache.metamodel.convert.ConvertedDataSetInterceptor

org.apache.metamodel.csv.CsvBigFileMemoryTest

org.apache.metamodel.csv.CsvDataContextTest

org.apache.metamodel.data.AbstractRow

org.apache.metamodel.data.RowPublisherDataSetTest

org.apache.metamodel.data.RowTest

org.apache.metamodel.data.SimpleDataSetHeader

org.apache.metamodel.delete.AbstractRowDeletionBuilder

org.apache.metamodel.delete.DeleteFrom

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