Обсуждение: Identification of serial fields
Hello: I continue to be working in my .NET Data provider for postgres 7.4, i want to know if there are a simple way for identify autoincrement fields, i see that for serial and big serial fields the default value is 'nextval(...)' this can be a way for know it but i want to know if there are a better way :) Thanks in advance. -- Best regards Carlos Guzmán Álvarez Vigo-Spain
On Sat, 2003-08-02 at 17:19, Carlos Guzman Alvarez wrote:
> Hello:
>
> I continue to be working in my .NET Data provider for postgres 7.4, i
> want to know if there are a simple way for identify autoincrement
> fields, i see that for serial and big serial fields the default value is
> 'nextval(...)' this can be a way for know it but i want to know if there
> are a better way :)
In SERIAL columns the sequence depends on the column, so the association
can be gathered from pg_depend.
Check for a relation between a sequence and column of a table where the
deptype = 'i'. (Taken from pg_dump)
SELECT c.oid, relname, relacl, relkind,
relnamespace,
(select usename from pg_user where relowner = usesysid) as usename,
relchecks, reltriggers,
relhasindex, relhasrules, relhasoids,
d.refobjid as owning_tab,
d.refobjsubid as owning_col
from pg_class c
join pg_depend d on (c.relkind = 'S' and d.classid = c.tableoid and d.objid = c.oid and d.objsubid = 0 and
d.refclassid= c.tableoid and d.deptype = 'i')
where relkind in ('t', 'S', 'v')
order by c.oid
;
Hello: > In SERIAL columns the sequence depends on the column, so the association > can be gathered from pg_depend. > > Check for a relation between a sequence and column of a table where the > deptype = 'i'. (Taken from pg_dump) Thanks very much i will try it and comment the results here :) -- Best regards Carlos Guzmán Álvarez Vigo-Spain
Hello: > Thanks very much i will try it and comment the results here :) This is was i'm finally using for retirve column information: SELECT pg_namespace.nspname AS TABLE_SCHEMA, pg_class.relname AS TABLE_NAME, pg_attribute.attname AS COLUMN_NAME, pg_attribute.atttypid AS DATA_TYPE, pg_attribute.attlen AS COLUMN_SIZE, pg_attribute.attndims AS COLUMN_DIMENSIONS, pg_attribute.attnum AS ORDINAL_POSITION, pg_attribute.atthasdef AS HAS_DEFAULT, pg_attrdef.adsrc AS COLUMN_DEFAULT, pg_attribute.attnotnull AS IS_NOT_NULL, (pg_depend.objid is not null) AS IS_AUTOINCREMENT, case pg_attribute.attstorage when 'p' THEN 'PLAIN' when 'e' THEN 'EXTERNAL' when 'm' THEN 'MAIN' when 'x' THEN 'EXTENDED' END AS STORAGE, pg_description.description AS DESCRIPTION FROM pg_attribute left join pg_class ON pg_attribute.attrelid = pg_class.oid left join pg_namespace ON pg_class.relnamespace = pg_namespace.oid left join pg_attrdef ON (pg_class.oid = pg_attrdef.adrelid AND pg_attribute.attnum = pg_attrdef.adnum) left join pg_description ON (pg_attribute.attrelid = pg_description.objoid AND pg_attribute.attnum = pg_description.objsubid) left join pg_depend ON (pg_attribute.attrelid = pg_depend.objid AND pg_depend.deptype = 'i') WHERE pg_attribute.attisdropped = false AND pg_attribute.attnum > 0 ORDER BY pg_namespace.nspname, pg_class.relname, pg_attribute.attnum I'm not sure now if it's 100% correct but the first tests seems to work, i will try to make more tests tomorrow :) -- Best regards Carlos Guzmán Álvarez Vigo-Spain
Hello: Finally after some tests i'm doing this: SELECT pg_namespace.nspname AS TABLE_SCHEMA, pg_class.relname AS TABLE_NAME, pg_attribute.attname AS COLUMN_NAME, pg_attribute.atttypid AS DATA_TYPE, pg_attribute.attlen AS COLUMN_SIZE, pg_attribute.attndims AS COLUMN_DIMENSIONS, pg_attribute.attnum AS ORDINAL_POSITION, pg_attribute.atthasdef AS HAS_DEFAULT, pg_attrdef.adsrc AS COLUMN_DEFAULT, pg_attribute.attnotnull AS IS_NOT_NULL, (pg_depend.objid is not null) AS IS_AUTOINCREMENT, case pg_attribute.attstorage when 'p' THEN 'PLAIN' when 'e' THEN 'EXTERNAL' when 'm' THEN 'MAIN' when 'x' THEN 'EXTENDED' END AS STORAGE, pg_description.description AS DESCRIPTION FROM pg_attribute left join pg_class ON pg_attribute.attrelid = pg_class.oid left join pg_namespace ON pg_class.relnamespace = pg_namespace.oid left join pg_attrdef ON (pg_class.oid = pg_attrdef.adrelid AND pg_attribute.attnum = pg_attrdef.adnum) left join pg_description ON (pg_attribute.attrelid = pg_description.objoid AND pg_attribute.attnum = pg_description.objsubid) left join pg_depend ON (pg_attribute.attrelid = pg_depend.refobjid AND pg_attribute.attnum = pg_depend.refobjsubid AND pg_depend.deptype = 'i') WHERE pg_attribute.attisdropped = false AND pg_attribute.attnum > 0 ORDER BY pg_namespace.nspname, pg_class.relname, pg_attribute.attnum -- Best regards Carlos Guzmán Álvarez Vigo-Spain