How to continue Script execution if table doesn't exist.

[#1]

I have my main data table broke down in to few tables using subset function. Then I am doing some operations and trying to merge them back using the update function. But sometime time I only have one table and sometimes 2 tables. How can I tell script to continue if second table doesn't exist. 

// Update data tables
Data Table( "Material A" ) << Update(
With( Data Table( "Material B" ) ),
Match Columns( :SN = :SN )

How can I tell script that if Material A or Material B table not exist, still continue execution. 

[#2 · Accepted solution]

You could use Try-statement or you could check if those tables exist before updating. Personally I would perform a check instead of relying on Try. Also usually it is better to use variables to store references to tables instead of relying on the table names.

Edit: Using Try would look something like this (https://www.jmp.com/support/help/en/17.2/#page/jmp/throw-and-catch-exceptions.shtml)

Try(
	Data Table("Big Class") << Update(
		With(Data Table("Big Class Families")),
		Match Columns(:name = :name)
	)
);

and check for table names

tablelist = Get Data Table List() << get name;
// Only join if both are found
If(Contains(tablelist, "Big Class") & Contains(tablelist, "Big Class Families"),
	Data Table("Big Class") << Update(
		With(Data Table("Big Class Families")),
		Match Columns(:name = :name)
	)
);

[#3]

Thanks for the solutions and advice to use variables to store references to tables instead of relying on the table names.

[#4]

If you use variables then you could also use Is Empty(dtref)

Names Default To Here(1);

dt = Open("$SAMPLE_DATA/Big Class.jmp");
Try(dt2 = Open("$SAMPLE_DATA/Big Class Families"));
Show(Is Empty(dt), Is Empty(dt2));

but you might have to use other methods, depending where you are getting your tables (you can figure out a way to use Try() if nothing else seems to work).