ABL triggers do not cover SQL operations. This is a self join case and emgr is a foreign key that refers to the primary key eid. create table employee (eid int primary key, ename varchar (30), emgr int, foreign key (emgr) references employee (eid)). Another column in a table can refer to primary key of the same table. From ABL, someone can programmatically disable triggers using the DISABLE TRIGGERS statement. It is not possible even in self join case. Then we will not know that this code has been changed. The ABL code of the trigger can be illegally replaced by someone. The ABL trigger is not part of the database and must be stored separately in the file system.Ģ. Right?īut it is inconvenient for database exploitation:ġ. Suppose the use of FK is not possible in OpenEdge at the SQL level.Īt the OpenEdge ABL level to implement something like referential integrity I have to write an ABL procedure for the trigger to delete, create, etc. Am I wrong again? If I'm wrong, what is this article for? It is a bug? Where it is a bug, in the article or in my code above? The target column of a foreign key constraint has to have a 'primary key' or 'unique' constraint on it. Here is the basic syntax: CREATE TABLE childtable ( childkey INTEGER, CONSTRAINT fkname FOREIGN KEY (childkey) REFERENCES parenttable (parentkey) ) Let’s create a simple example with customers and. You can’t add them to existing tables with ALTER TABLE. /SQL-command-to-add-a-FOREIGN-KEY-constraint-to-an-existing-table-fails-with-the-error-7545įrom this article I conclude that it is still possible at the SQL level. SQLite supports foreign keys in which the referencing table and the referenced table are the same table. You can only define foreign keys using the CREATE TABLE statement in SQLite. There also use the PUB scheme in the example. Judging by this article, this is possible, but only need to be sure that the table columns chosen as primary or foreign key do not accept NULL values by making them mandatory. I wanna to create a foreign key between Order.Cust_Num and Customer.Cust_Num fields. Both fields have the MANDATORY option:ĪDD FIELD "Cust_Num" OF "Customer" AS characterĪDD FIELD "Name" OF "Customer" AS characterĪDD FIELD "Order_Num" OF "Order" AS characterĪDD FIELD "Cust_Num" OF "Order" AS character These are the data definitions for my two test tables. Make sure that the table columns chosen as primary or foreign key do not accept NULL values by making them mandatory. SQL Error : No matching key defined for the referenced table (7545)Ĭolumns defining a primary or foreign key must not accept the NULL value. I do it in the Dbeaver. But I got the following error: Foreign Key Syntax in SQL tablename is the name of the table where the FOREIGN KEY constraint is to be defined columnname is the name of the column where. In our example, a relationship would be defined between CustomerID in the Orders table (the. I am trying to add a foreign key to my existing table using by SQL command.ĪLTER TABLE PUB."Order" ADD CONSTRAINT ORDER_CUSTOMER_FK FOREIGN KEY ("Cust_Num") REFERENCES PUB."Customer"("Cust_Num") The foreign key is referred to as the source column or just column. Also notice that a foreign key column in one table does not have to have the same name as the primary key column that it refers to in another table.
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