SQLite 3.8

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create table Texts
( tid integer not null primary key AUTOINCREMENT
, textval varchar(20) not null unique);



create index x1 on texts (textval);
create table T
( x int not null 
, tid int not null references texts (tid)
, primary key (x, tid) );
create view v as 
   select t.x, texts.textval
   from t
   join texts
       on t.tid = texts.tid
;
CREATE TRIGGER trig1 
INSTEAD OF INSERT ON V 
BEGIN
        
        -- insert unless textval is already in place
        INSERT INTO texts (textval)
        SELECT NEW.textval FROM (VALUES(1))
        WHERE NOT EXISTS (
            SELECT 1 FROM texts WHERE textval = NEW.textval 
        );

        --lookup tid for textval
        insert into t (x, tid)
        select NEW.x, texts.tid
        from texts where texts.textval = NEW.textval;

END;
insert into V (x,textval) values (1,'a');  
insert into V (x,textval) values (5,'bb');  
insert into V (x,textval) values (15,'a'); 
select * from v;


x
textval


1
a

5
bb

15
a


select * from texts;


tid
textval


1
a

2
bb


select * from t;


x
tid


1
1

5
2

15
1