// Generate SQL for COUNT
DataTableSql GenCount()
{
var sql = _gen.SelectCount(GetFrom());
var newtable = DataTableSql.CreateFromSql(DataHeading.Empty, sql);
return(newtable);
}
// generate SQL code for dyadic set operations
DataTableSql DyadicSet(DataTableSql other, DataHeading newheading, JoinOps joinop)
{
var sql = _gen.SelectSet(GetFrom(), other.GetFrom(), newheading, joinop);
var newtable = DataTableSql.CreateFromSql(newheading, sql);
return(newtable);
}
// generate SQL code for dyadic join operations
DataTableSql DyadicJoin(DataTableSql other, DataHeading joinhdg, DataHeading newheading)
{
var sql = _gen.SelectJoin(GetFrom(), other.GetFrom(), newheading, joinhdg);
var newtable = DataTableSql.CreateFromSql(newheading, sql);
return(newtable);
}
public override DataTable Transform(DataHeading heading, ExpressionEval[] exprs)
{
_database.RegisterExpressions(exprs);
var sql = _gen.SelectAs(GetFrom(), exprs);
var newtable = DataTableSql.CreateFromSql(heading, sql);
Logger.WriteLine(4, "[Trn '{0}']", newtable);
return(newtable);
}
public override DataTable Project(ExpressionEval[] exprs)
{
var heading = DataHeading.Create(exprs);
var sql = _gen.SelectAs(GetFrom(), exprs);
var newtable = DataTableSql.CreateFromSql(heading, sql);
Logger.WriteLine(4, "[Pro '{0}']", newtable);
return(newtable);
}
public override DataTable Rename(ExpressionEval[] exprs)
{
// note: heading order must match exprs (cf Local)
var heading = DataHeading.Create(exprs);
var sql = _gen.SelectAs(GetFrom(), exprs);
var newtable = DataTableSql.CreateFromSql(heading, sql);
Logger.WriteLine(4, "[Ren '{0}']", newtable);
return(newtable);
}
public override DataTable TransformAggregate(DataHeading heading, ExpressionEval[] exprs)
{
_database.RegisterExpressions(exprs);
// groups must include all cols that are input to anything other than Aggregate
var groups = GroupColumns(exprs);
var sql = _gen.SelectAsGroup(GetFrom(), exprs, groups);
var newtable = DataTableSql.CreateFromSql(heading, sql);
newtable.HasGroupBy = true;
Logger.WriteLine(4, "[TrnA '{0}']", newtable);
return(newtable);
}
public override DataTable TransformOrdered(DataHeading heading, ExpressionEval[] exprs, ExpressionEval[] orderexps)
{
_database.RegisterExpressions(exprs);
var names = exprs.Where(e => e.IsProject).Select(e => e.Name);
var isagg = exprs.Any(e => e.HasFold);
var allin = orderexps.All(o => names.Contains(o.Name));
// if all ordering fields are in exprs then add order to newtable, else to this table
if (!allin)
{
AddOrderBy(orderexps);
}
var sql = (isagg) ? _gen.SelectAsGroup(GetFrom(), exprs, GroupColumns(exprs))
: _gen.SelectAs(GetFrom(), exprs);
var newtable = DataTableSql.CreateFromSql(heading, sql);
if (allin)
{
newtable.AddOrderBy(orderexps);
}
newtable.HasGroupBy = isagg;
Logger.WriteLine(4, "[TrnO '{0}']", newtable);
return(newtable);
}