Examples with AstLimit com.developmentontheedge.sql.model.AstLimit used on opensource projects

Example 6 with AstLimit

use of com.developmentontheedge.sql.model.AstLimit in project be5 by DevelopmentOnTheEdge.

the class DB2Transformer method transformSelect.

@Override
protected void transformSelect(AstSelect select) {
    AstLimit limit = select.getLimit();
    if (limit != null) {
        if (limit.getOffset() == 0)
            limit.setShape("FETCH FIRST", "ROWS ONLY");
        else {
            if (select.getOrderBy() == null)
                throw new IllegalStateException("The ranking function \"ROW_NUMBER\" must have an ORDER BY clause");
            select.dropLimit();
            SimpleNode parent = select.jjtGetParent();
            int idx = parent.indexOf(select);
            AstIdentifierConstant tmp = new AstIdentifierConstant("tmp");
            AstIdentifierConstant rn = new AstIdentifierConstant("rn");
            AstSelectList list = select.getSelectList();
            AstTableRef tableRef = new AstTableRef(select);
            tableRef.setAsToken(true);
            tableRef.addChild(tmp);
            AstFrom from = new AstFrom(tableRef);
            AstWhere where = new AstWhere();
            AstBetweenPredicate between = new AstBetweenPredicate(new AstFieldReference(tmp, rn), AstNumericConstant.of(limit.getOffset()), AstNumericConstant.of(limit.getOffset() + limit.getLimit()));
            where.addChild(between);
            AstSelect newSelect = new AstSelect((AstSelectList) list.clone(), from, where);
            AstFunNode func = parserContext.getFunction("row_number").node();
            AstDerivedColumn derCol = new AstDerivedColumn(new AstWindowFunction(func, new AstWindowSpecification(select.getOrderBy())));
            select.dropOrder();
            derCol.setPrefixComma(true);
            derCol.setAsToken(true);
            derCol.addChild(rn);
            if (list.isAllColumns()) {
                for (AstTableRef tr : select.getFrom().tableRefs()) {
                    String tableName = tr.getAlias() == null ? tr.getTable() : tr.getAlias();
                    list.addChild(new AstFieldReference(new AstIdentifierConstant(tableName), new AstIdentifierConstant("*")));
                }
            }
            list.addChild(derCol);
            parent.jjtAddChild(newSelect, idx);
        }
    }
    super.transformSelect(select);
}