internal string TryGetTableAlias(string alias)
{
TableChainer ctable = GetPrevTable(Statement.StatementIndex);
if (alias == null)
{
if (ctable != null && ctable is FromChainer)
{
return(ctable.Alias.Name);
}
}
else
{
while (ctable != null)
{
if (ctable != null && ctable.Alias.Name == alias)
{
return(alias);
}
ctable = ctable.GetPrevTable(Statement.StatementIndex);
}
}
Throw(QueryTalkExceptionType.TargetTableNotFound, String.Format("target alias = {0}", alias ?? Text.ClrNull));
return(null);
}
// Get target table by alias.
// anticipated:
// If alias is not given, then the target is the first table - which must be FromChainer.
private TableChainer GetTarget(ref string alias)
{
TableChainer ctable = GetPrevTable(Statement.StatementIndex);
if (alias == null)
{
if (ctable is FromChainer)
{
alias = ctable.Alias.Name;
return(ctable);
}
return(null);
}
while (ctable != null)
{
// case-sensitive comparison
if (ctable.Alias.Name.EqualsCS(alias))
{
return(ctable);
}
ctable = ctable.GetPrevTable(Statement.StatementIndex);
}
return(null); // not found
}
