Yes. Using a Lookup tile, you can look through your records to see if a match exists. If one does, then the Lookup tile becomes “defined,” and will output a value.
For example, if you were looking for existing records with the same data in the "Name" field, create a Lookup tile with the same field in the first three holes – Lookup ["Name"] for ["Name"] = ["Name"], and select the Relation you are working in in the fourth hole. Plug the Lookup tile into a Defined tile. Plug the Defined tile into the 1st hole of an If-Then-Else tile, and place the completed Lookup Abacus on the Template used for your entry form. If you select this Abacus as the validation for the field, it will prevent the entry of the record until the problem is resolved (see documentation on Data Validation for more details), and the message you type into the “Then” hole will be displayed on your form.
• Why is the total on my form blank?
If you are adding together a number of field entries with plus “+” tiles, all of the fields on the form must be assigned a value. Otherwise, if just one field is undefined, the entire calculation will be undefined. To create an automatic default to “0” use the Undefined Becomes tile in the calculation in the following manner: [Undefined [“value a”] Becomes [0]] + [Undefined [“value b”] becomes [“0”]] and so on. This type of calculation will add together numbers when they are present, and substitute “0” when no entry is present in a particular field.
If you are using a Total or Subtotal tile, you should use these tiles with the Undefined Becomes tile if you wish to insure that they always return a value (such as “0”). If none of the records they scan is defined, they will be undefined and not return a value. This may be necessary under some circumstances, but may not be desirable in others, including many financial applications.
• How can I sequentially number my records?
First create a field with a number-type format (name the Field icon “Record #,” or something similar). This field will be used as a Calculation Retain (an Abacus and a Field icon in the same Rectangle).
Second, make a calculation with the Max tile. In the tile hole, place the “Record #” field. Make an addition calculation with this tile that reads Max [“Record#”] + [1]. (You can use an Undefined Becomes tile to assign the first number.) Insert this Abacus into the same Data rectangle as the Field icon “Record #.” The Abacus will take the maximum value stored so far in the “Record #” field and add 1 to it. Remember to build an Index on the field.
• How do I connect If-Then-Else tiles together?
Typically, you would plug one If-Then-Else tile into the last hole (Else) of the preceding tile. If you have two or more values that belong in the Else part of the calculation, instead of inserting a value, plug in another If-Then-Else tile, and continue the selection process. You can then create a chain of these statements. (It is not unusual to plug one of these Tiles into either or both of the last two holes.)
• The “Else” in my If-Then-Else tile is not executing. What’s
wrong?
If the result of the “If” test is undefined, the tile becomes undefined. In other words, Undefined is not the same as false.
• Why don’t all my Abacus icons appear on the list in another
Abacus?
Helix does not allow you to use any Abacus that references the current Abacus. This keeps you from creating a situation where Helix needs to calculate the value of Abacus “A” in order to evaluate Abacus “B” and needs to calculate “B” to resolve “A.” In more conventional systems, it is possible to make such an error; this type of error is known as an “infinite loop.”
• Is there an easy way to get to the particular tile I’m looking for?
Yes there is! You can type the first letter(s) of a tile name to select that tile. For instance, by typing “loo”, the Abacus tiles will select the Lookup tile. Pressing the Tab key will then select the next tile that begins with “loo”. In this case, first the Lookup [ ] for [ ] = [ ] in [ ] tile would be selected; after pressing the Tab key, the Lookup [ ] Summary in [ ] tile would be selected. Another example is typing “-” first selects the [ ] - [ ] tile; pressing the Tab key then selects the - [ ] tile.
A space alone represents a black hole. The Display tile is selected by pressing the Option key and typing a space. Delta tiles are selected by typing Option-J.
