Question

Please help me to write a trigger that adds new rows to a table.

I have 3 tables in my database:

1. Regions (id, name); id – primary;
2. Technics (id, name); id – primary;
3. Availability (id, region, technic, count); id – primary, region – foreign on Regions.id, Technik – foreign on technics.id.

I want to add new row in Availability for each Technics row on adding row in Regions.

Somethink like:

procedure void OnAddNewRegion(int region)
{
    foreach (Row r in Technic)
    {
        Availability.Rows.Add(new Row(id, region, r.Id, 0));
    }
}

But in a SQL trigger.
I want to do the same on adding new Technics row.

Answer 1

try something like this (assuming Availability.id is an identity), which will also handle multiple rows being inserted at one time:

CREATE TRIGGER TR_Regions ON Regions 
FOR INSERT
AS
INSERT INTO Availability 
        (region, technic, count)
    SELECT
        i.id, t.id, 0
        FROM INSERTED            i
            CROSS JOIN Technics  t

GO

you don’t say how Regions joins with Technics, so I cross joined them (every inserted Regions, gets one row for every Technics).