I have a WKT data which looks like so:
GEOMETRYCOLLECTION(
POINT(-1763555.1165955865 310640.0829509564),
POINT(-1421117.229877997 -300856.1433304538)
)
The default projection is 'EPSG:3857'. In postgresql I created a parent table whith generic geometry column and several child tables with columns of specific geometry type. The schema looks like so:
# parent table with generic geometry column "geom"
CREATE TABLE "public"."layer_261_" (
"id" int4 DEFAULT nextval('layer_261__id_seq'::regclass) NOT NULL,
"feature_id" int4 DEFAULT 0 NOT NULL,
"feature_name" varchar(200),
"feature_type" varchar(50),
"geom" "public"."geometry",
"object_id" int4 DEFAULT 0 NOT NULL,
"row_id" int4 DEFAULT 0 NOT NULL
)
WITH (OIDS=FALSE);
ALTER TABLE "public"."layer_261_" ADD CHECK (st_srid(geom) = 3857);
ALTER TABLE "public"."layer_261_" ADD CHECK (st_ndims(geom) = 2);
ALTER TABLE "public"."layer_261_" ADD PRIMARY KEY ("id");
# child table which is supposed to contain only POINT data type
CREATE TABLE "public"."layer_261_points" (
"id" int4 DEFAULT nextval('layer_261__id_seq'::regclass) NOT NULL,
"feature_id" int4 DEFAULT 0 NOT NULL,
"feature_name" varchar(200),
"feature_type" varchar(50),
"geom" "public"."geometry",
"object_id" int4 DEFAULT 0 NOT NULL,
"row_id" int4 DEFAULT 0 NOT NULL
)
INHERITS ("public"."layer_261_")
WITH (OIDS=FALSE);
ALTER TABLE "public"."layer_261_points" ADD CHECK (st_ndims(geom) = 2);
ALTER TABLE "public"."layer_261_points" ADD CHECK (geometrytype(geom) = 'POINT'::text);
ALTER TABLE "public"."layer_261_points" ADD CHECK (st_srid(geom) = 3857);
So, how can I insert my data (two points to the database)? For example, I'm not sure whether I should convert points' coordinates to lat-lon. And besides, I'm not sure whether I should insert GEOMETRYCOLLECTION or all points one by one.
EDIT
I've just tried to execute a query with a real data point:
INSERT INTO layer_261_ (geom) VALUES (ST_Point(105177.3509204, -85609.471679397))
But as a result I got this error message:
new row for relation "layer_261_" violates check constraint
"enforce_srid_geom"
Does anybody know how to fix it?
EDIT
This query leads to the very same error message:
INSERT INTO layer_261_ (geom) VALUES (ST_SetSRID(ST_Point(105177.3509204, -85609.471679397),
4326))
You can only insert the WKT into the parent table because the point table won't accept a GEOMETRYCOLLECTION:
INSERT INTO "public"."layer_261_" ("geom", <other columns>)
VALUES (ST_GeomFromText(<your WKT>, 3857), <other values>);
Once you have the data in the parent table you can easily convert from the GEOMETRYCOLLECTION to separate POINTs using ST_Dump() and insert those in the point table:
INSERT INTO "public"."layer_261_points" ("geom", <other columns>)
SELECT p.geom, <other columns>
FROM "public"."layer_261_" m, ST_Dump("geom") p
WHERE ...;
You can of course also forget about the first step and do ST_Dump(ST_GeomFromText(<your WKT>, 3857)) in the second step but that is less intuitive and more prone to errors.
Note that ST_Dump() is a table function so it should be used in a FROM clause. It can then use columns from tables specified before the function.
The error you were getting from using ST_Point() is because you the geometry has a NULL SRID. You should set that explicitly with ST_SetSRID() (one of my great annoyances with PostGIS...).
Related
CREATE TABLE instances(
ser_name VARCHAR(20) NOT NULL,
id INTEGER NOT NULL ,
ser_ip VARCHAR(16) NOT NULL,
status VARCHAR(10) NOT NULL,
creation_ts TIMESTAMP,
CONSTRAINT instance_id PRIMARY KEY(id)
);
CREATE TABLE characters(
nickname VARCHAR(15) NOT NULL,
type VARCHAR(10) NOT NULL,
c_level INTEGER NOT NULL,
game_data VARCHAR(40) NOT NULL,
start_ts TIMESTAMP ,
end_ts TIMESTAMP NULL ,
player_ip VARCHAR(16) NOT NULL,
instance_id INTEGER NOT NULL,
player_username VARCHAR(15),
CONSTRAINT chara_nick PRIMARY KEY(nickname)
);
ALTER TABLE
instances ADD CONSTRAINT ins_ser_name FOREIGN KEY(ser_name) REFERENCES servers(name);
ALTER TABLE
instances ADD CONSTRAINT ins_ser_ip FOREIGN KEY(ser_ip) REFERENCES servers(ip);
ALTER TABLE
characters ADD CONSTRAINT chara_inst_id FOREIGN KEY(instance_id) REFERENCES instances(id);
ALTER TABLE
characters ADD CONSTRAINT chara_player_username FOREIGN KEY(player_username) REFERENCES players(username);
insert into instances values
('serverA','1','138.201.233.18','active','2020-10-20'),
('serverB','2','138.201.233.19','active','2020-10-20'),
('serverE','3','138.201.233.14','active','2020-10-20');
insert into characters values
('characterA','typeA','1','Game data of characterA','2020-07-18 02:12:12','2020-07-18 02:32:30','192.188.11.1','1','nabin123'),
('characterB','typeB','3','Game data of characterB','2020-07-19 02:10:12',null,'192.180.12.1','2','rabin123'),
('characterC','typeC','1','Game data of characterC','2020-07-18 02:12:12',null,'192.189.10.1','3','sabin123'),
('characterD','typeA','1','Game data of characterD','2020-07-18 02:12:12','2020-07-18 02:32:30','192.178.11.1','2','nabin123'),
('characterE','typeB','3','Game data of characterE','2020-07-19 02:10:12',null,'192.190.12.1','1','rabin123'),
('characterF','typeC','1','Game data of characterF','2020-07-18 02:12:12',null,'192.188.10.1','3','sabin123'),
('characterG','typeD','1','Game data of characterG','2020-07-18 02:12:12',null,'192.188.13.1','1','nabin123'),
('characterH','typeD','3','Game data of characterH','2020-07-19 02:10:12',null,'192.180.17.1','2','bipin123'),
('characterI','typeD','1','Game data of characterI','2020-07-18 02:12:12','2020-07-18 02:32:30','192.189.18.1','3','dhiraj123'),
('characterJ','typeD','3','Game data of characterJ','2020-07-18 02:12:12',null,'192.178.19.1','2','prabin123'),
('characterK','typeB','4','Game data of characterK','2020-07-19 02:10:12','2020-07-19 02:11:30','192.190.20.1','1','rabin123'),
('characterL','typeC','2','Game data of characterL','2020-07-18 02:12:12',null,'192.192.11.1','3','sabin123'),
('characterM','typeC','3','Game data of characterM','2020-07-18 02:12:12',null,'192.192.11.1','2','sabin123');
here I need a view that shows the name of the server, the id of the instance and the number of active sessions (a session is active if the end timestamp is null). do my code wrong or something else? i am starting to learn so hoping for positive best answers.
my view
create view active_sessions as
select i.ser_name, i.id, count(end_ts) as active
from instances i, characters c
where i.id=c.instance_id and c.end_ts = null
group by i.ser_name, i.id;
This does not do what you want:
where i.id = c.instance_id and c.end_ts = null
Nothing is equal to null. You need is null to check a value against null.
Also, count(end_ts) will always produce 0, as we know already that end_ts is null, which count() does not consider.
Finally, I would highly recommend using a standard join (with the on keyword), rather than an implicit join (with a comma in the from clause): this old syntax from decades ago should not be used in new code. I think that a left join is closer to what you want (it would also take in account instances that have no character at all).
So:
create view active_sessions as
select i.ser_name, i.id, count(c.nickname) as active
from instances i
left join characters c on i.id = c.instance_id and c.end_ts is null
group by i.ser_name, i.id;
I want to create e temp table using select into syntax. Like:
select top 0 * into #AffectedRecord from MyTable
Mytable has a primary key. When I insert record using merge into syntax primary key be a problem. How could I drop pk constraint from temp table
The "SELECT TOP (0) INTO.." trick is clever but my recommendation is to script out the table yourself for reasons just like this. SELECT INTO when you're actually bringing in data, on the other hand, is often faster than creating the table and doing the insert. Especially on 2014+ systems.
The existence of a primary key has nothing to do with your problem. Key Constraints and indexes don't get created when using SELECT INTO from another table, the data type and NULLability does. Consider the following code and note my comments:
USE tempdb -- a good place for testing on non-prod servers.
GO
IF OBJECT_ID('dbo.t1') IS NOT NULL DROP TABLE dbo.t1;
IF OBJECT_ID('dbo.t2') IS NOT NULL DROP TABLE dbo.t2;
GO
CREATE TABLE dbo.t1
(
id int identity primary key clustered,
col1 varchar(10) NOT NULL,
col2 int NULL
);
GO
INSERT dbo.t1(col1) VALUES ('a'),('b');
SELECT TOP (0)
id, -- this create the column including the identity but NOT the primary key
CAST(id AS int) AS id2, -- this will create the column but it will be nullable. No identity
ISNULL(CAST(id AS int),0) AS id3, -- this this create the column and make it nullable. No identity.
col1,
col2
INTO dbo.t2
FROM t1;
Here's the (cleaned up for brevity) DDL for the new table I created:
-- New table
CREATE TABLE dbo.t2
(
id int IDENTITY(1,1) NOT NULL,
id2 int NULL,
id3 int NOT NULL,
col1 varchar(10) NOT NULL,
col2 int NULL
);
Notice that the primary key is gone. When I brought in id as-is it kept the identity. Casting the id column as an int (even though it already is an int) is how I got rid of the identity insert. Adding an ISNULL is how to make a column nullable.
By default, identity insert is set to off here to this query will fail:
INSERT dbo.t2 (id, id3, col1) VALUES (1, 1, 'x');
Msg 544, Level 16, State 1, Line 39
Cannot insert explicit value for identity column in table 't2' when IDENTITY_INSERT is set to OFF.
Setting identity insert on will fix the problem:
SET IDENTITY_INSERT dbo.t2 ON;
INSERT dbo.t2 (id, id3, col1) VALUES (1, 1, 'x');
But now you MUST provide a value for that column. Note the error here:
INSERT dbo.t2 (id3, col1) VALUES (1, 'x');
Msg 545, Level 16, State 1, Line 51
Explicit value must be specified for identity column in table 't2' either when IDENTITY_INSERT is set to ON
Hopefully this helps.
On a side-note: this is a good way to play around with and understand how select insert works. I used a perm table because it's easier to find.
How to alter existing column auto increment in existing DB2-Table?
If you created a table with a normal column, like an id column here:
CREATE TABLE demo_tab
(id int NOT NULL PRIMARY KEY,
col_txt VARCHAR(20)
);
but later you decided to have it like this one with the GENERATED ALWAYS AS IDENTITY clause:
CREATE TABLE demo_tab
(id int NOT NULL GENERATED ALWAYS AS IDENTITY (START WITH 1 INCREMENT BY 1) PRIMARY KEY,
col_txt VARCHAR(20)
);
use this statement:
ALTER TABLE demo_tab ALTER COLUMN id
SET GENERATED ALWAYS AS IDENTITY (START WITH 1 INCREMENT BY 1);
and do not forget about reorganising the table:
CALL SYSPROC.ADMIN_CMD('REORG TABLE demo_tab');
if you want modify your identityvalue try this
ALTER TABLE yourtable ALTER COLUMN youridentitycomunname RESTART WITH yourcountervalue
I have Table A. Table A owns a sequence.
I create Table B, inheriting from Table A.
Table A and B now use the same default value for their primary key column.
For a simplified example, Table A is "person", and B is "bulk_upload_person".
CREATE TABLE "testing"."person" (
"person_id" serial, --Resulting DDL: int4 NOT NULL DEFAULT nextval('person_person_id_seq'::regclass)
"public" bool NOT NULL DEFAULT false
);
--SQL Ran
CREATE TABLE "testing"."bulk_upload_person" (
"upload_id" int4 NOT NULL
)
INHERITS ("testing"."person");
--Resulting DDL
CREATE TABLE "testing"."bulk_upload_person" (
"person_id" int4 NOT NULL DEFAULT nextval('person_person_id_seq'::regclass),
"public" bool NOT NULL DEFAULT false,
"upload_id" int4 NOT NULL
)
INHERITS ("testing"."person");
For table A, I can get the sequence by using pg_get_table_serial_seqence.
How can I get and then set the next value of the sequence if I only know about Table B? I want to add n to the value.
I need to do this in order to populate multiple related objects at once, while being able to know what primary IDs they will have, rather than having to query the tables I've just populated to determine the IDs.
By populate, I mean inserting multiple rows in one statement.
insert into "testing"."bulk_upload_person" ( "person_id", "public", "upload_id") values ( '1', 'f', '1'), ( '2', 't', '1'); --etc
I think our situation is similar to https://stackoverflow.com/a/8007835/89211 but we don't want to keep the lock on the table beyond getting and setting the next value of the serial for each table.
Currently we are doing this by getting the name of the sequence by regexing the default value of the primary key for Table B, but it feels like there's probably a better way to do this that we don't realise.
There is this field in a table:
room_id INT NOT NULL CONSTRAINT room_id_ref_room REFERENCES room
I have three 2 tables for two kinds of rooms: standard_room and family_room
How to do something like this:
room_id INT NOT NULL CONSTRAINT room_id_ref_room REFERENCES standard_room or family_room
I mean, room_id should reference either standard_room or family_room.
Is it possible to do so?
Here is the pattern I've been using.
CREATE TABLE room (
room_id serial primary key,
room_type VARCHAR not null,
CHECK CONSTRAINT room_type in ("standard_room","family_room"),
UNIQUE (room_id, room_type)
);
CREATE_TABLE standard_room (
room_id integer primary key,
room_type VARCHAR not null default "standard_room",
FOREIGN KEY (room_id, room_type) REFERENCES room (room_id, room_type),
CHECK CONSTRAINT room_type = "standard_room"
);
CREATE_TABLE family_room (
room_id integer primary key,
room_type VARCHAR not null default "family_room",
FOREIGN KEY (room_id, room_type) REFERENCES room (room_id, room_type),
CHECK CONSTRAINT room_type = "family_room"
);
That is, the 'subclasses' point at the super-class, by way of a type descriminator column (such that the pointed to base class is of the correct type, and that primary key of the super class is the same as the child classes.
Here's the same SQL from the accepted answer that works for PostGres 12.8. There's a few issues not only the CREATE_TABLE syntax mistake:
CREATE TABLE room (
room_id serial primary key,
room_type VARCHAR not null,
CONSTRAINT room_in_scope CHECK (room_type in ('standard_room','family_room')),
CONSTRAINT unique_room_type_combo UNIQUE (room_id, room_type)
);
CREATE TABLE standard_room (
room_id integer primary key,
room_type VARCHAR not null default 'standard_room',
CONSTRAINT roomid_std_roomtype_fk FOREIGN KEY (room_id, room_type) REFERENCES public."room" (room_id, room_type),
CONSTRAINT std_room_constraint CHECK (room_type = 'standard_room')
);
CREATE TABLE family_room (
room_id integer primary key,
room_type VARCHAR not null default 'family_room',
CONSTRAINT roomid_fam_roomtype_fk FOREIGN KEY (room_id, room_type) REFERENCES "room" (room_id, room_type),
CONSTRAINT fam_room_constraint CHECK (room_type = 'family_room')
);
NOTE: The SQL above uses constraints to enforce the child room_type values default to the parent tables' room_type values: 'standard_room' or 'family_room'.
PROBLEM: Since the child tables Primary Key's expect either the standard and family room Primary Key that means you can't insert more than one record in thsee two child tables.
insert into room (room_type) VALUES ('standard_room'); //Works
insert into room (room_type) values ('family_room'); //Works
insert into standard_room (room_id,pictureAttachment) VALUES (1,'Before Paint'); //Works
insert into standard_room (room_id,pictureAttachment) VALUES (1,'After Paint'); //Fails
insert into standard_room (room_id,pictureAttachment) VALUES (1,'With Furniture');
insert into family_room (room_id,pictureAttachment) VALUES (2, 'Beofre Kids'); //Works
insert into family_room (room_id,pictureAttachment) VALUES (2,'With Kids'); //Fails
To make the tables accept > 1 row you have to remove the Primary Keys from the 'standard_room' and 'family_room' tables which is BAD database design.
Despite 26 upvotes I will ping OP about this as I can see the answer was typed free hand.
Alternate Solutions
For smallish tables with less than a handful of variations a simple alterative is a single table with Bool columns for different table Primary Key fields.
Single Table "Room"
Id
IsStandardRoom
IsFamilyRoom
Desc
Dimensions
1
True
False
Double Bed, BIR
3 x 4
2
False
True
3 Set Lounge
5.5 x 7
SELECT * FROM Room WHERE IsStdRoom = true;
At the end of the day, in a relational database it's not very common to be adding Room Types when it involves creating the necessary related database tables using DDL commands (CREATE, ALTER, DROP).
A typical future proof database design allowing for more Tables would look something like this:
Multi Many-To-Many Table "Room"
Id
TableName
TableId
1
Std
8544
2
Fam
236
3
Std
4351
Either Standard or Family:
select * from standard_room sr where sr.room_id in
(select TableId from room where TableName = 'Std');
select * from family_room fr where fr.room_id in
(select id from room where TableName = 'Fam');
Or both:
select * from standard_room sr where sr.room_id in
(select TableId from room where TableName = 'Std')
UNION
select * from family_room fr where fr.room_id in
(select id from room where TableName = 'Fam');
Sample SQL to demo Polymorphic fields:
If you want to have different Data Types in the polymorphic foreign key fields then you can use this solution. Table r1 stores a TEXT column, r2 stores a TEXT[] Array column and r3 a POLYGON column:
CREATE OR REPLACE FUNCTION null_zero(anyelement)
RETURNS INTEGER
LANGUAGE SQL
AS $$
SELECT CASE WHEN $1 IS NULL THEN 0 ELSE 1 END;
$$;
CREATE TABLE r1 (
r1_id SERIAL PRIMARY KEY
, r1_text TEXT
);
INSERT INTO r1 (r1_text)
VALUES ('foo bar'); --TEXT
CREATE TABLE r2 (
r2_id SERIAL PRIMARY KEY
, r2_text_array TEXT[]
);
INSERT INTO r2 (r2_text_array)
VALUES ('{"baz","blurf"}'); --TEXT[] ARRAY
CREATE TABLE r3 (
r3_id SERIAL PRIMARY KEY
, r3_poly POLYGON
);
INSERT INTO r3 (r3_poly)
VALUES ( '((1,2),(3,4),(5,6),(7,8))' ); --POLYGON
CREATE TABLE flex_key_shadow (
flex_key_shadow_id SERIAL PRIMARY KEY
, r1_id INTEGER REFERENCES r1(r1_id)
, r2_id INTEGER REFERENCES r2(r2_id)
, r3_id INTEGER REFERENCES r3(r3_id)
);
ALTER TABLE flex_key_shadow ADD CONSTRAINT only_one_r
CHECK(
null_zero(r1_id)
+ null_zero(r2_id)
+ null_zero(r3_id)
= 1)
;
CREATE VIEW flex_key AS
SELECT
flex_key_shadow_id as Id
, CASE
WHEN r1_id IS NOT NULL THEN 'r1'
WHEN r2_id IS NOT NULL THEN 'r2'
WHEN r3_id IS NOT NULL THEN 'r3'
ELSE 'wtf?!?'
END AS "TableName"
, CASE
WHEN r1_id IS NOT NULL THEN r1_id
WHEN r2_id IS NOT NULL THEN r2_id
WHEN r3_id IS NOT NULL THEN r3_id
ELSE NULL
END AS "TableId"
FROM flex_key_shadow
;
INSERT INTO public.flex_key_shadow (r1_id,r2_id,r3_id) VALUES
(1,NULL,NULL),
(NULL,1,NULL),
(NULL,NULL,1);
SELECT * FROM flex_key;