Re: currval, lastval, nextvar?

Thank you all for the good information.  The three "insert" lines are
all I need.

Carol

On Apr 23, 2009, at 11:59 AM, A. Kretschmer wrote:

> In response to Carol Walter :
>> Hello,
>>
>> I want write a query that will insert a record in a person table,
>> insert a record in a presentation table, and then insert a record
>> into
>> a bridge table that contains the keys of both of the newly created
>> records from the other two tables.  According to the documentation,
>> takes the next number in the sequence and reports it.  Both currval
>> and lastval report the last value that was taken from the sequence,
>> but both will produce errors if a "nextval" was not called in the
>> current session.  Does writing a record that automatically updates a
>> sequence count as calling nextval?
>
> Yes. You don't need call nextval.
>
> You can do something like :
>
> test=# create table t1(id serial primary key);
> NOTICE:  CREATE TABLE will create implicit sequence "t1_id_seq" for
> serial column "t1.id"
> NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index
> "t1_pkey"
> for table "t1"
> CREATE TABLE
> test=*# create table t2(id serial primary key);
> NOTICE:  CREATE TABLE will create implicit sequence "t2_id_seq" for
> serial column "t2.id"
> NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index
> "t2_pkey"
> for table "t2"
> CREATE TABLE
> test=*# create table brige (i1 int references t1, i2 int references
> t2);
> CREATE TABLE
> test=*# insert into t1 values(default);
> INSERT 0 1
> test=*# insert into t2 values(default);
> INSERT 0 1
> test=*# insert into brige values (currval('t1_id_seq'),
> currval('t2_id_seq'));
> INSERT 0 1
> test=*# select * from brige ;
> i1 | i2
> ----+----
>  1 |  1
> (1 Zeile)
>
>
> --
> Andreas Kretschmer
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