I use Postgres and I've integration app which write data to database. My column should not be null but my app send null value. I tried to set default value but query override this rule with null value. How can i handle this change without code.
My Column configuration looks like this.
If you won't or can't change the query in code, you have to use trigger
If you can change code structure and query:
If the column has a default value, then no need to send NULL value to query
-- Before change
insert into your_table (id, name, default_col) values
(1, 'name', null);
-- After change (remove null data)
insert into your_table (id, name) values
(1, 'name');
Or send default value in insert query
-- Before change
insert into your_table (id, name, default_col) values
(1, 'name', null);
-- After change (Use default keyboard)
insert into your_table (id, name, default_col) values
(1, 'name', default);
Related
I need to use the returning value of the Table A (ID) and insert it in Table B as a parameter:
insert into tableA (ID, Name , Address)
values (GEN_ID(GENERATOR,1),'John','123 street')
returning ID
--Example: ID=159
insert into tableB (ID, TABLE_A_FK )
values (GEN_ID(GENERATOR,1), 159)
Instead of entering the actual value 159, can I create like a variable (e.g. declare ID int;), and just pass the parameter?
The only way to do this in a single statement, is to use EXECUTE BLOCK (basically an anonymous one-off procedure). It uses the same syntax as normal stored procedures in Firebird.
You can do:
execute block
as
declare id integer;
begin
insert into tableA (ID, Name , Address)
values (GEN_ID(GENERATOR,1), 'John', '123 street')
returning ID
into id;
insert into tableB (ID, TABLE_A_FK)
values (GEN_ID(GENERATOR,1), :id);
end
If necessary, execute block statements can be parameterized, so you can use parameters to provide values (instead of hard coding them). See the link above for details.
I am having trouble getting MERGE statements to work properly, and I have recently started to try to use checksums.
In the toy example below, I cannot get this row to insert (1, 'ANDREW', 334.3) that is sitting in the staging table.
DROP TABLE TEMP1
DROP TABLE TEMP1_STAGE
-- create table
CREATE TABLE TEMP1
(
[ID] INT,
[NAME] VARCHAR(55),
[SALARY] FLOAT,
[SCD] INT
)
-- create stage
CREATE TABLE TEMP1_STAGE
(
[ID] INT,
[NAME] VARCHAR(55),
[SALARY] FLOAT,
[SCD] INT
)
-- insert vals into stage
INSERT INTO TEMP1_STAGE (ID, NAME, SALARY)
VALUES
(1, 'ANDREW', 333.3),
(2, 'JOHN', 555.3),
(3, 'SARAH', 444.3)
-- insert stage table into main table
INSERT INTO TEMP1
SELECT *
FROM TEMP1_STAGE;
-- clean up stage table
TRUNCATE TABLE TEMP1_STAGE;
-- put some new values in the stage table
INSERT INTO TEMP1_STAGE (ID, NAME, SALARY)
VALUES
(1, 'ANDREW', 334.3),
(4, 'CARL', NULL)
-- CHECKSUMS
update TEMP1_STAGE
set SCD = binary_checksum(ID, NAME, SALARY);
update TEMP1
set SCD = binary_checksum(ID, NAME, SALARY);
-- run merge
MERGE TEMP1 AS TARGET
USING TEMP1_STAGE AS SOURCE
-- match
ON (SOURCE.[ID] = TARGET.[ID])
WHEN NOT MATCHED BY TARGET
THEN INSERT (
[ID], [NAME], [SALARY], [SCD]) VALUES (
SOURCE.[ID], SOURCE.[NAME], SOURCE.[SALARY], SOURCE.[SCD]);
-- the value: (1, 'ANDREW', 334.3) is not merged in
SELECT * FROM TEMP1;
How can I use the checksum to my advantage in the MERGE?
Your issue is that the NOT MATCHED condition is only considering the ID values specified in the ON condition.
If you want duplicate, but distinct records, include SCD to the ON condition.
If (more likely) your intent is that record ID = 1 be updated with the new SALARY, you will need to add a WHEN MATCHED AND SOURCE.SCD <> TARGET.SCD THEN UPDATE ... clause.
That said, the 32-bit int value returned by the `binary_checksum()' function is not sufficiently distinct to avoid collisions and unwanted missed updates. Take a look at HASHBYTES instead. See Binary_Checksum Vs HashBytes function.
Even that may not yield your intended performance gain. Assuming that you have to calculate the hash for all records in the staging table for each update cycle, you may find that it is simpler to just compare each potentially different field before the update. Something like:
WHEN MATCHED AND (SOURCE.NAME <> TARGET.NAME OR SOURCE.SALARY <> TARGET.SALARY)
THEN UPDATE ...
Even then, you need to be careful of potential NULL values and COLLATION. Both NULL <> 50000.00 and 'Andrew' <> 'ANDREW' may not give you the results you expect. It might be easiest and most reliable to just code WHEN MATCHED THEN UPDATE ....
Lastly, I suggest using DECIMAL instead of FLOAT for Salary.
I created a table which contains a column of string ARRAY type as:
CREATE TABLE test
(
id integer NOT NULL,
list text[] COLLATE pg_catalog."default",
CONSTRAINT test_pkey PRIMARY KEY (id)
)
I then added rows which contain various values for that array, including an empty array and missing data (null):
insert into test (id, list) values (1, array['one', 'two', 'three']);
insert into test (id, list) values (2, array['four']);
insert into test (id, list) values (3, array['']);
insert into test (id, list) values (4, array[]::text[]); // empty array
insert into test (id, list) values (5, null); // missing value
pgAdmin shows table like this:
I am trying to get a row which contains a null value ([null]) in the list column but:
select * from test where list = null;
...returns no rows and:
select * from test where list = '{}';
...returns row with id = 4.
How to write WHERE clause which would target NULL value for column of ARRAY type?
demo:db<>fiddle
... WHERE list IS NULL
select * from test where list IS null;
Like this:
select * from test where list IS NULL;
I need to know if there is any possibility of passing null in blob data using insert statement in Informix.
I know there is an option of LOAD FROM <FILE> INSERT INTO <TABLE>
Which works well, but i am looking for some insert statment, because i am implementing liquibase and i am not finding any way to insert null or leave it in insert values so that it can accept null. This field is set to TRUE for null values.
Error I am getting is following
[Error Code: -617, SQL State: IX000] A blob data type must be supplied within this context.
Tried this
INSERT INTO informix.tti_key_store (id, code, description, value_asc, cts, active)
VALUES
(4, 'EVDSDEALER', 'EVDS Dealer Passphrase', 'nodYzUNAs+htD1Mng3hYYg==', DATETIME (2016-02-17 12:51:34.000) YEAR TO FRACTION(5), 'T')
Tried this
INSERT INTO informix.tti_key_store (id, code, description, value_asc, value_bin, cts, active)
VALUES
(4, 'EVDSDEALER', 'EVDS Dealer Passphrase', 'nodYzUNAs+htD1Mng3hYYg==', NULL, DATETIME (2016-02-17 12:51:34.000) YEAR TO FRACTION(5), 'T')
value_bin is a blob field set to NULL to true.
In postgres I have two tables like so
CREATE TABLE foo (
pkey SERIAL PRIMARY KEY,
name TEXT
);
CREATE TABLE bar (
pkey SERIAL PRIMARY KEY,
foo_fk INTEGER REFERENCES foo(pkey) NOT NULL,
other TEXT
);
What I want to do is to write a .sql script file that does the following
INSERT INTO foo(name) VALUES ('A') RETURNING pkey AS abc;
INSERT INTO bar(foo_fk,other) VALUES
(abc, 'other1'),
(abc, 'other2'),
(abc, 'other3');
which produces the error below in pgAdmin
Query result with 1 row discarded.
ERROR: column "abc" does not exist
LINE 3: (abc, 'other1'),
********** Error **********
ERROR: column "abc" does not exist
SQL state: 42703
Character: 122
Outside of a stored procedure how do a define a variable that I can use between statements? Is there some other syntax for being able to insert into bar with the pkey returned from the insert to foo.
You can combine the queries into one. Something like:
with foo_ins as (INSERT INTO foo(name)
VALUES ('A')
RETURNING pkey AS foo_id)
INSERT INTO bar(foo_fk,other)
SELECT foo_id, 'other1' FROM foo_ins
UNION ALL
SELECT foo_id, 'other2' FROM foo_ins
UNION ALL
SELECT foo_id, 'other3' FROM foo_ins;
Other option - use an anonymous PL/pgSQL block like:
DO $$
DECLARE foo_id INTEGER;
BEGIN
INSERT INTO foo(name)
VALUES ('A')
RETURNING pkey INTO foo_id;
INSERT INTO bar(foo_fk,other)
VALUES (foo_id, 'other1'),
(foo_id, 'other2'),
(foo_id, 'other3');
END$$;
You can use lastval() to ...
Return the value most recently returned by nextval in the current session.
This way you do not need to know the name of the seqence used.
INSERT INTO foo(name) VALUES ('A');
INSERT INTO bar(foo_fk,other) VALUES
(lastval(), 'other1')
, (lastval(), 'other2')
, (lastval(), 'other3')
;
This is safe because you control what you called last in your own session.
If you use a writable CTE as proposed by #Ihor, you can still use a short VALUES expression in the 2nd INSERT. Combine it with a CROSS JOIN (or append the CTE name after a comma (, ins) - same thing):
WITH ins AS (
INSERT INTO foo(name)
VALUES ('A')
RETURNING pkey
)
INSERT INTO bar(foo_fk, other)
SELECT ins.pkey, o.other
FROM (
VALUES
('other1'::text)
, ('other2')
, ('other3')
) o(other)
CROSS JOIN ins;
Another option is to use currval
INSERT INTO foo
(name)
VALUES
('A') ;
INSERT INTO bar
(foo_fk,other)
VALUES
(currval('foo_pkey_seq'), 'other1'),
(currval('foo_pkey_seq'), 'other2'),
(currval('foo_pkey_seq'), 'other3');
The automatically created sequence for serial columns is always named <table>_<column>_seq
Edit:
A more "robust" alternative is to use pg_get_serial_sequence as Igor pointed out.
INSERT INTO bar
(foo_fk,other)
VALUES
(currval(pg_get_serial_sequence('public.foo', 'pkey')), 'other1'),
(currval(pg_get_serial_sequence('public.foo', 'pkey')), 'other2'),
(currval(pg_get_serial_sequence('public.foo', 'pkey')), 'other3');