-- Table: ccm21.seaoutlets
drop view v_selected;
create view v_selected as(
select gid,wso_id,the_geom from ccm21.seaoutlets where system_cd not in ('C','N','I','H','V')
except (select gid,wso_id,the_geom from ccm21.seaoutlets where 
system_cd = 'M' and sea_cd =5));

create view v_notselected as(
select gid,wso_id,the_geom from ccm21.seaoutlets where system_cd in ('C','N','I','H','V')
union (select gid,wso_id,the_geom from ccm21.seaoutlets where 
system_cd = 'M' and sea_cd =5));

-- below to hasten the Qgis load of that view

INSERT INTO geometry_columns(f_table_catalog, f_table_schema, f_table_name, f_geometry_column, coord_dimension, srid, "type")
SELECT '', 'public', 'v_selected', 'the_geom', ST_CoordDim(the_geom), ST_SRID(the_geom), GeometryType(the_geom)
FROM v_selected LIMIT 1;

-- deleting catchment outside area

delete from ccm21.catchments where wso_id in (
select wso_id from ccm21.seaoutlets where system_cd  in ('C','N','I','H','V')
UNION (select wso_id from ccm21.seaoutlets where 
system_cd = 'M' and sea_cd =5));

delete from ccm21.coast where wso_id in (
select wso_id from ccm21.seaoutlets where system_cd  in ('C','N','I','H','V')
UNION (select wso_id from ccm21.seaoutlets where 
system_cd = 'M' and sea_cd =5));

delete from ccm21.lakes where wso_id in (
select wso_id from ccm21.seaoutlets where system_cd  in ('C','N','I','H','V')
UNION (select wso_id from ccm21.seaoutlets where 
system_cd = 'M' and sea_cd =5));

delete from ccm21.mainrivers where wso_id in (
select wso_id from ccm21.seaoutlets where system_cd  in ('C','N','I','H','V')
UNION (select wso_id from ccm21.seaoutlets where 
system_cd = 'M' and sea_cd =5));

delete from ccm21.namedrivers where wso_id in (
select wso_id from ccm21.seaoutlets where system_cd  in ('C','N','I','H','V')
UNION (select wso_id from ccm21.seaoutlets where 
system_cd = 'M' and sea_cd =5));

delete from ccm21.rivernodes where wso_id in (
select wso_id from ccm21.seaoutlets where system_cd  in ('C','N','I','H','V')
UNION (select wso_id from ccm21.seaoutlets where 
system_cd = 'M' and sea_cd =5));

delete from ccm21.riversegments where wso_id in (
select wso_id from ccm21.seaoutlets where system_cd in ('C','N','I','H','V')
UNION (select wso_id from ccm21.seaoutlets where 
system_cd = 'M' and sea_cd =5));

delete from ccm21.seaoutlets where wso_id in (
select wso_id from ccm21.seaoutlets where system_cd in ('C','N','I','H','V')
UNION (select wso_id from ccm21.seaoutlets where 
system_cd = 'M' and sea_cd =5));


drop view if exists v_selected;
drop view if exists  v_notselected;
DELETE FROM geometry_columns where f_table_name = 'v_selected';
DELETE FROM geometry_columns where f_table_name = 'v_notselected';

Il seems that one basin is lacking in Turkey, not really a pb, finally it is not selected or not select, and since I discard the basins outside, it remains...
Don't forget to run vacuum and reindex on tables