TRIGGER

Keyword TRIGGER

Syntax:

    CREATE TRIGGER triggerName (BEFORE|AFTER|INSTEAD OF) (INSERT|DELETE|UPDATE) ON tableName (Statement|Function)

Example A

    alasql.fn.check = function(r) {
         if(r.n == 42) return false; // Do not insert on this number 
    };
    alasql('CREATE TRIGGER mytrigger BEFORE INSERT ON mytable check');

Example B

    alasql.fn.onchange = function(r) {
        if(r.a == 123) console.log('Observable event!');
    };;
    alasql('CREATE TABLE one (a INT)');
    alasql('CREATE TRIGGER two BEFORE INSERT ON one CALL onchange()');
    alasql('INSERT INTO one VALUES (123)');  // This will fire onchange()

Limitations:

• No INSTEAD OF DELETE
• No AFTER DELETE
• BEFORE DELETE can not prevent record from deletion