Re: syntax pb

On 5/30/23 06:45, Marc Millas wrote:
> Hi,
>
> I always have had difficulties to understand syntax. So...
>
> If I have:
> create table t1 (t text);
> create table t2 (a text, b text, c test, d numeric);

Is c supposed to be text?
Or are you indeed referring to some unspecified type?

> insert into t1('azerty');
> INSERT 0 1
> fine !

Not with that syntax:

insert into t1('azerty');
ERROR: syntax error at or near "'azerty'"
LINE 1: insert into t1('azerty');

insert into t1 values('azerty');
INSERT 0 1

>
>
> so, now, if I write:
> Select distinct test1.t, 'abc' as b, NULL as c, NULL as d
> From t1 test1;
>    t      |  b   | c  | d
> --------+-----+---+---
>  azerty | abc |   |
> (1 row)
>
> ok.

Yes

>
> and , now, if I want to insert that:
> Insert into t2 (a, b, c, d)
> Select distinct test1.t, 'abc' as b, NULL as c, NULL as d
> From t1 test1;
>
> I get:
> ERROR:  column "d" is of type numeric but expression is of type text
> LINE 2: Select distinct test1.t, 'abc' as b, NULL as c, NULL as d
>
> HINT:  You will need to rewrite or cast the expression.
>
> Can someone give a short SQL syntax hint ?

The hint is that though NULL is unknown it can have a type.

To get this to work I first did:

create table t2 (a text, b text, c text, d numeric);

to have c be text for simplicity sake.

Then I did:

Insert into t2 (a, b, c, d)
Select distinct test1.t, 'abc' as b, NULL::test, NULL::numeric
From t1 test1;

which results in:

select * from t2;
a | b | c | d
--------+-----+------+------
azerty | abc | NULL | NULL

>
> thanks,
>
>
>
> Marc MILLAS
> Senior Architect
> +33607850334
> www.mokadb.com <http://www.mokadb.com>
>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com