Built-in Triggers

Introduction

See also Form Triggers.

Essentially, the built-in triggers perform certain checks and, if the checks are successful, update the database accordingly. When a new record has been entered in a form, and an attempt is made to exit the line, the built-in triggers generate the following events:

  • They check that values have been assigned to all the columns comprising any unique key(s).
  • If the check succeeds, the line is successfully exited, the record is inserted into the form’s base table, and an automatic value is given to the autounique key in that record, if there is one (increasing the counter by 1).
  • If the check fails, an error message appears and the user cannot leave the line without clearing it or adding the missing values from the unique key.

When the user designates a unique key that already exists in the database, the built-in triggers automatically fill in all columns in the record. This is one way to retrieve an existing record from the database. There is then an automatic shift from insert mode into update mode, and the retrieved record can be modified, as desired. If, however, no such record exists in the database, then you remain in insert mode and a new record is created.

When the user specifies a new record, the built-in triggers verify that imported data exist in their respective join tables. If this verification check is successful, and all columns in any of the join table’s unique keys have been filled in, then the built-in triggers automatically fill in any other columns in the form that are imported from that table.

When an existing record is updated in a form, the system performs the same verification checks that are activated during record insertion. Once all update checks are successful, the record is updated in the database.

Priority’s built-in triggers also prevent the violation of referential integrity. That is, they do not allow the deletion of any record containing a column that is imported into another form (including the column that links an upper-level form to its sub-level). Once all deletion checks are successful, the record is deleted from the database.

Finally, built-in triggers perform privilege checks. That is, they check whether or not the user is authorized to modify the database. Only an authorized user will be able to insert, update or delete a record.

In sum, there are several types of built-in triggers:

  • field triggers, which fill in and verify column values
  • insert triggers, which verify the values in the row and insert the record in the table if the verification check is successful
  • update triggers, which verify the updated values in the row and update the record if the verification check is successful
  • delete triggers, which check for referential integrity and delete the record if the check is successful.

Field triggers are activated when the form column is exited. The other built-in triggers are activated when the row is exited.

The built-in insert, update and delete triggers only affect the form’s base table. If the form is to insert, update or delete records of other tables, you must write your own POST-INSERT, POST-UPDATE and/or POST-DELETE triggers.

Example: The STARTDATE column in the Service Calls form (DOCUMENTS_Q) is from the SERVCALLS table (whereas the base table of the DOCUMENTS_Q form is DOCUMENTS). There are therefore POST-INSERT, POST-UPDATE and POST-DELETE triggers for this form that generate the insert/update/delete of records in the SERVCALLS table.

Field Triggers

If, when in insert mode, you fill in all columns that make up the base table's unique key (which is often a single column, like ORDNAME or CUSTNAME), then the entire record is automatically retrieved and there is an automatic shift from insert mode to update mode. This function is carried out by Priority's built-in field triggers. The following code displays the built-in POST-FIELD trigger for the ORDERS form.


Note: Examples here and below are taken from a file created by the Dump Form utility (run via the SQL Development program, by selecting Form from the Dump menu). The result is the SQL queries of the form, including the triggers of that form, both built-in and user-defined.


ORDERS/ORDNAME/POST-FIELD TRIGGER:
----------------------------------
#line 1 ORDERS/ORDNAME/POST-FIELD
SET TRANSACTION;
GOTO 9 WHERE :NEXTPATTERNFLAG = 1;
SELECT CURDATE, BOOKNUM, FORECASTFLAG, DETAILS, REFERENCE, QPRICE, PERCENT, DISPRICE, VAT, 
TOTPRICE, QPROFIT, ADJPRICEFLAG, ADVBAL, ADVPERCENT, BSHN_OPENDATE, TYPE, CLOSED, PCLOSED, 
LEXCHANGE, DOER, AGENT, BRANCH, CURRENCY, CUST, DEAL, DESTCODE, LCURRENCY, ORD, ORD, ORD, ORD,
ORDSTATUS, ORDTYPE, PAY, PHONE, PLIST, PROF, PROJ, SHIPTYPE, USER, WARHS
INTO :ORDERS.CURDATE, :ORDERS.BOOKNUM, :ORDERS.FORECASTFLAG, :ORDERS.DETAILS, 
:ORDERS.REFERENCE, :ORDERS.QPRICE, :ORDERS.PERCENT, :ORDERS.DISPRICE, 
:ORDERS.VAT, :ORDERS.TOTPRICE, :ORDERS.QPROFIT, :ORDERS.ADJPRICEFLAG, :ORDERS.ADVBAL,
:ORDERS.ADVPERCENT, :ORDERS.BSHN_OPENDATE, :ORDERS.TYPE, :ORDERS.CLOSED,
:ORDERS.PCLOSED, :ORDERS.LEXCHANGE, :ORDERS.DOER, :ORDERS.AGENT, :ORDERS.BRANCH, 
:ORDERS.CURRENCY, :ORDERS.CUST, :ORDERS.DEAL, :ORDERS.DESTCODE, :ORDERS.LCURRENCY, 
:ORDERS.LINKDOC, :ORDERS.NSCUST, :ORDERS.ORD, :ORDERS.ORDS, :ORDERS.ORDSTATUS, 
:ORDERS.ORDTYPE, :ORDERS.PAY, :ORDERS.PHONE, :ORDERS.PLIST, 
:ORDERS.PROF, :ORDERS.PROJ, :ORDERS.SHIPTYPE, :ORDERS.USER, :ORDERS.WARHS
FROM ORDERS
WHERE ORDNAME = :ORDERS.ORDNAME;
LABEL 9;
:TABFORM = 22;#line 1 ORDERS/ORDNAME/POST-FIELD
SELECT BRANCH INTO :$.BRANCH FROM USERSA WHERE :$.ORD = 0
AND :$.BRANCH = 0 AND USER = SQL.USER;
COMMIT;

When inserting a new record, the built-in triggers verify that imported data exist in the join table.

Example: Built-in triggers do not allow you to specify an order made by a customer that does not appear in the CUSTOMERS table.

#line 1 ORDERS/CUSTNAME/CHECK-FIELD
GOTO 1 WHERE :ORDERS.CUSTNAME = '';
SELECT 'X'
FROM CUSTOMERS
WHERE CUSTNAME = :ORDERS.CUSTNAME;
SELECT 192 INTO :SCREENMSG
FROM DUMMY WHERE :RETVAL = 0;
LABEL 1;

Once all columns in any of the join table’s unique keys are filled in (provided that all verification checks are successful), Priority will automatically fill in any columns in the form that are imported from that table. Thus, once a valid customer number is designated in the Sales Orders form, the corresponding customer name will be filled in automatically.

#line 1 ORDERS/CUSTNAME/POST-FIELD
SET TRANSACTION;
SELECT CUSTDES, CUST, CUST, CURRENCY, LINKDATE, PAY, SHIPTYPE, MCUST, NSFLAG, PAYCUST, 
SECONDLANGTEXT, VATFLAG
INTO :ORDERS.CUSTDES, :ORDERS.CUST, :ORDERS.CUSTA, :ORDERS.CUSTCURRENCY, 
:ORDERS.CUSTLINKDATE, :ORDERS.CUSTPAY, :ORDERS.CUSTSHIPTYPE, :ORDERS.MCUST, 
:ORDERS.NSFLAG, :ORDERS.PAYCUST, :ORDERS.SECONDLANGTEXT, :ORDERS.VATFLAG
FROM CUSTOMERS
WHERE CUSTNAME = :ORDERS.CUSTNAME;

Note: For technical reasons, the CUSTDES column is hidden in the ORDERS form, and the CDES column is displayed instead. A POST-FIELD trigger copies the value of CUSTDES into CDES.

Insert Triggers

When a line is exited, Priority’s built-in insert triggers check that values have been assigned to all the columns comprising any unique key(s); they provide an automatic value to that table’s autounique key (increasing the autounique counter by 1); and they insert the new record into the form’s base table.

ORDERS INSERT TRIGGER:
SET TRANSACTION;
INSERT INTO ORDERS ( CURDATE, ORDNAME, BOOKNUM, FORECASTFLAG, DETAILS, REFERENCE, QPRICE, PERCENT,
DISPRICE, VAT, TOTPRICE, QPROFIT, ADJPRICEFLAG, ADVBAL, ADVPERCENT, TYPE, CLOSED, PCLOSED, 
LEXCHANGE, DOER, AGENT, BRANCH, CURRENCY, CUST, DEAL, DESTCODE, LCURRENCY, ORD, ORD, ORD, ORD,
ORDSTATUS, ORDTYPE, PAY, PHONE, PLIST, PROF, PROJ, SHIPTYPE, USER, WARHS)
VALUES ( :ORDERS.CURDATE, :ORDERS.ORDNAME, :ORDERS.BOOKNUM, :ORDERS.FORECASTFLAG, :ORDERS.DETAILS,
:ORDERS.REFERENCE, :ORDERS.QPRICE, :ORDERS.PERCENT, :ORDERS.DISPRICE, :ORDERS.VAT, :ORDERS.TOTPRICE,
:ORDERS.QPROFIT, :ORDERS.ADJPRICEFLAG, :ORDERS.ADVBAL, :ORDERS.ADVPERCENT, :ORDERS.TYPE, 
:ORDERS.CLOSED, :ORDERS.PCLOSED, :ORDERS.LEXCHANGE, :ORDERS.DOER, :ORDERS.AGENT, :ORDERS.BRANCH,
:ORDERS.CURRENCY, :ORDERS.CUST, :ORDERS.DEAL, :ORDERS.DESTCODE, :ORDERS.LCURRENCY, :ORDERS.LINKDOC,
:ORDERS.NSCUST, :ORDERS.ORD, :ORDERS.ORDS, :ORDERS.ORDSTATUS, :ORDERS.ORDTYPE, :ORDERS.PAY,
:ORDERS.PHONE, :ORDERS.PLIST, :ORDERS.PROF, :ORDERS.PROJ, :ORDERS.SHIPTYPE, :ORDERS.USER,
:ORDERS.WARHS);
SELECT 189 INTO :SCREENMSG FROM DUMMY WHERE :RETVAL = 0;
SELECT ORD, ORD, ORD, ORD
INTO :ORDERS.LINKDOC, :ORDERS.NSCUST, :ORDERS.ORD, :ORDERS.ORDS
FROM ORDERS
WHERE ORDNAME = :ORDERS.ORDNAME;

Update Triggers

In addition to most of the functions performed by the insert triggers, Priority’s built-in update triggers ensure that no column which links one form to another form has been updated.

Example: If the PART form were linked to the PARTARC form (which stores child parts) via the part catalogue number (PARTNAME), then that number could not be changed once a child part was assigned. This problem is easily resolved by linking the forms through the autounique key (PART), as the column in that key is not updateable. Rather, its value is automatically assigned by the system.

Delete Triggers

Priority’s delete triggers prevent the violation of referential integrity. That is, they do not allow the deletion of any record containing a column that is imported into another form (including the column that links an upper-level form to its sub-level).

ORDERS/DELETE TRIGGER:
#line 1 ORDERS/DELETE
SELECT ENTMESSAGE('ORDERITEMS','F',0) INTO :PROGPARAM FROM DUMMY;
SELECT 94 INTO :PROGMSG 
FROM ORDERITEMS WHERE (:$1.ORD <> 0 AND ORD = :$1.ORD );

More on Triggers