Alpha to MySQL Logical Fields - Interesting Discovery

[gkpurcey]

Hi,

This post was going to be a question on how to get this to work, but I ended up finding a way to make it work. Although the behavior is a little different than I expected.

Allow me to explain:

I have an Alpha table with a number of Logical fields. Unfortunately, when I set it up, I did not use field rules to enforce the fields to be "F" if they were not "T", so I ended up having a lot of the logical fields being Nulls. This does not seem to bother Alpha in the least, as it appears to assume that Null is False.

When I exported the table into MySQL, using the default settings of the File/Export menu choice, all of the logical fields were imported as Null, including the ones that were supposed to be "T". Not good.

So I edited the default create table SQL in the export function so that each of the logical fields would be created as a "NOT NULL" field. When I did this, and tried to export, the insert query failed when it tried to include a Null value from the Alpha field into the new MYSQL table.

Now here is the odd part. The export function, by default, says it uses "<All Fields>". But when I went into that option, and actually selected all the fields, then the insert query worked, and set the non-True logical fields to False in the new MYSQL Table.

I would be interested to find out if anyone else has experienced this same behavior.

Also, hope this helps someone who finds themselves in a similar quandry.

Gordon Purcey

[CALocklin]

Re: Alpha to MySQL Logical Fields - Interesting Discovery

I haven't converted anything to MySQL so I can't comment on that.

However, watch out for this one:

This does not seem to bother Alpha in the least, as it appears to assume that Null is False.

While A5 does assume that in some cases, there are also some situations where the null value will return TRUE. I can't recall right now exactly where that is but it might be when getting the value from a field object like:
result = parentform:T_F_field_object_name.value

Play it safe and make sure your logical fields ALWAYS have a default value. If you really can't do that, be very, very careful how you get the current value and test any method you use on a blank/null field just in case.

[Steve Wood]

Re: Alpha to MySQL Logical Fields - Interesting Discovery

Speaking from the Web side, I always default my tinyint(1) to zero (false) and never use tinyint(1) for anything other than Alpha-logical. If I need a 1-digit integer, I use smallint(1).

[gkpurcey]

Re: Alpha to MySQL Logical Fields - Interesting Discovery

Thanks to both of you for the sound advice...