Re: [Help-glpk] Database connectivity in MathProg

[Andrew Makhorin]

> Especially when connecting to data sources like csv files, or
> spreadsheets which do not contain meta information identifying keys it is
> necessary that MathProg defines which columns are the keys if UPDATE and
> INSERT are to be used.

> This is why AMPL is identifying key columns with brackets [] in the table out 
> statement.

> Implementing a syntax
> table t OUT ... : {...}->[k ~ K, ...], ...;
> will not cause significantly more effort for the programmer then
> table t {...} OUT ... : k ~ K, ...;
> but will convey the necessary information to uniquely identify the key 
> columns for the data base interface.
> If this looks more appealing to You, You might use:
> table t {...} OUT ... : [k ~ K, ...], ...;

I could suggest other solution: the driver obtains information about key
fileds, say, from strings or column names; for example, if a column name
begins with '_', it could mean that this is the key column (in which
case '_' is just ignored).

In any case I think to implement the table feature as simply as
possible, because many details are still unclear and should be
implemented later, if necessary.