Currently I'm creating an app that can essentially create post-it notes. I'm working on making my SQL tables for it. What I want to do is make it so the tables data is searchable by date. Multiple posts may be made on a day obviously. So I'm putting the date into a separate table. What I'm wondering is if it's possible to make it so the date column on the date table is not the current date that it will auto increment the Id and create a new column with the current date
CREATE TABLE IF NOT EXISTS ideas (
id SERIAL PRIMARY KEY,
ideas text,
date_id int );
CREATE TABLE IF NOT EXISTS date (
id SERIAL PRIMARY KEY,
table_date CONVERT(VARCHAR(15), GETDATE(),10));
Is the code I have so far any and all suggestions are welcome!
I would recommend using a TRIGGER procedure. You can trigger a function every time an insert is made on the ideas table. This function can check the dates table and make sure the current date exists in there. It can even set the new id of that date in the date_id column in the ideas table.
For example:
DROP TABLE IF EXISTS ideas;
CREATE TABLE ideas (
id SERIAL PRIMARY KEY,
ideas text,
date_id int
);
-- "date" is a reserved word. try to avoid naming a table "date".
DROP TABLE IF EXISTS dates;
CREATE TABLE dates (
id SERIAL PRIMARY KEY,
table_date DATE DEFAULT NOW() -- i would recommend the DATE type here
);
DROP TRIGGER IF EXISTS insert_date_if_absent ON ideas;
DROP FUNCTION IF EXISTS insert_date_if_absent();
CREATE FUNCTION insert_date_if_absent()
RETURNS TRIGGER
AS $$
DECLARE
today date := now();
new_date_id integer;
BEGIN
IF NOT EXISTS (SELECT * FROM dates WHERE table_date = today) THEN
INSERT INTO dates (table_date) VALUES (today) RETURNING id INTO new_date_id;
ELSE
SELECT id FROM dates WHERE table_date = today INTO new_date_id;
END IF;
IF NEW.date_id IS NULL THEN
NEW.date_id := new_date_id;
END IF;
RETURN NEW;
END
$$ LANGUAGE PLPGSQL;
CREATE TRIGGER insert_date_if_absent
BEFORE INSERT ON ideas
FOR EACH ROW
EXECUTE PROCEDURE insert_date_if_absent();
This will allow you to omit date_id when inserting into ideas. If omitted, it will get automatically set by the trigger to the id of today's date.
INSERT INTO ideas (ideas) VALUES ('sup dudeee');
Some other feedback which I incorporated in my answer:
Do not store dates as a VARCHAR, it's less efficient and more hassle. Use a DATE instead.
Do not name tables after reserved words in Postgres. Rather than date, name it dates.
Related
order.date must be between item.date_from and item.date_to... what are the different ways of doing that?
CREATE TABLE "item" (
"id" SERIAL PRIMARY KEY,
"date_from" DATE NOT NULL,
"date_to" DATE NOT NULL
);
CREATE TABLE "order" (
"id" SERIAL PRIMARY KEY,
"date" DATE NOT NULL
);
CREATE TABLE "order_item" (
"order" INTEGER NOT NULL REFERENCES "order",
"item" INTEGER NOT NULL REFERENCES "item"
);
Check constraints work on simple expressions. For example, a simple sanity check on the order: check( date > '2010-01-01'). There's also exclusion constraints which check no two rows have the same value as defined by the exclusion. But, with the exception of foreign key constraints, constraints don't query other tables.
You can solve this with a trigger on insert and update, and I'll go into that below, but its better to solve this sort of problem with referential integrity. However, I can't think of a way to do that.
You can make a view of available items for the order. Here $1 is the date of the order.
create temporary view items_available_to_order
select *
-- pluralize table names to avoid conflicting with keywords and columns
from items
-- date_from and date_to has become a single daterange when_available
where items.when_available #> $1
Then only insert items from that view.
If you want to go the trigger route (you can do both) write a function which checks whether an order's item is valid. It either raises an exception or returns a trigger. new is the inserted row, or the row after an update.
I changed some of the table and column names and types to avoid common pitfalls.
create function check_item_order_is_valid()
returns trigger
language 'plpgsql'
as $body$
declare
item_is_available boolean;
begin
select
items.when_available #> orders.ordered_on into item_is_available
from item_orders
join items on items.id = new.order_id
join orders on orders.id = new.item_id;
if( not item_is_available) then
raise exception 'Item #% is not available for order #%',
new.item_id, new.order_id;
end if;
return new;
end
$body$
Then define a trigger to call the function when rows are inserted or updated in the item/order table.
create trigger check_item_orders
before insert or update
on item_orders
for each row
execute function check_item_order_is_valid();
Demonstration.
What if the valid range of an item changes? You need an update trigger on item to check that its orders are still valid. Maybe. Depends on your business logic.
A test example:
CREATE OR REPLACE FUNCTION public.item_date()
RETURNS trigger
LANGUAGE plpgsql
AS $function$
DECLARE
order_date date;
from_date date;
to_date date;
BEGIN
select into order_date "date" from "order" where id = new.order;
select into from_date, to_date date_from, date_to from item where id = new.item;
--Use date range to test whether order date is in item date range.
if order_date <# daterange(from_date, to_date, '[]') then
return new;
else
return null;
end if;
END;
$function$
create trigger item_date_check before insert or update on order_item for each row execute function item_date();
insert into item values (1, '09/01/2021', '10/31/2021');
insert into item values (2, '07/01/2021', '08/31/2021');
insert into "order" values (1, '09/05/2021');
insert into order_item values (1, 1);
NOTICE: Order date 2021-09-05, from_date 2021-09-01, to_date 2021-10-31
INSERT 0 1
--Returning NULL causes the INSERT not to happen.
insert into order_item values (1, 2);
NOTICE: Order date 2021-09-05, from_date 2021-07-01, to_date 2021-08-31
INSERT 0 0
Note that I had to quote "order" as that is a reserved word also. You might to take a look at Key(reserved) Words. For range functions/operators see Range Function. For general information on range(s) see Range Types
create or replace trigger addDate
before insert or update on Employee
for each row
begin
for EmployeeRec in
(
select * from employee
)
loop
if (EmployeeRec.DateLimit > sysdate) then
raise_application_error (-20001, 'You are only allowed to insert once a day, please try again
tomorrow');
end if;
end loop EmployeeRec;
:NEW.DateLimit := sysdate + 1;
end;
/
show errors;
Need to be able to insert a record for a day only. Any other records must wait till the next day
There is PLS 00049 ERROR at New.DateLimit
Maybe column name is not DateLimit, but Date_Limit.
If I am following you correctly, you want to allow just one record per day, as defined by column date_limit.
You don't need a trigger for this. One option uses a computed column and a unique constraint.
create table employee (
employee_id int primary key,
name varchar2(100),
date_limit date default sysdate,
day_limit date generated always as (trunc(date_limit)) unique
);
day_limit is a computed column, that contains the date portion of date_limit (with the time portion removed). A unique constraint is set on this column, so two rows cannot have date_limits that belong to the same day.
Demo on DB Fiddle
Say I have a unique column of VarChar(32).
ex. 13bfa574e23848b68f1b7b5ff6d794e1.
I want to preserve the uniqueness of this while converting the column to int. I figure I can convert all of the letters to their ascii equivalent, while retaining the numbers and character position. To do this, I will use the translate function.
psuedo code: select translate(uid, '[^0-9]', ascii('[^0-9]'))
My issue is finding all of the letters in the VarChar column originally.
I've tried
select uid, substring(uid from '[^0-9]') from test_table;
But it only returns the first letter it encounters. Using the above example, I would be looking for bfaebfbbffde
Any help is appreciated!
First off, I agree with the two commenters who said you should use a UID datatype.
That aside...
Your UID looks like a traditional one, in that it's not alphanumeric, it's hex. If this is the case, you can convert the hex to the numeric value using this solution:
PostgreSQL: convert hex string of a very large number to a NUMERIC
Notice the accepted solution (mine, shame) is not as good as the other solution listed, as mine will not work for hex values this large.
That said, yikes, what a huge number. Holy smokes.
Depending on how many records are in your table and the frequency of insert/update, I would consider a radically different approach. In a nutshell, I would create another column to store your numeric ID whose value would be determined by a sequence.
If you really want to make it bulletproof, you can also create a cross-reference table to store the relationships that would
Reuse an ID if it ever repeated (I know UIDs don't, but this would cover cases where a record is deleted by mistake, re-appears, and you want to retain the original id)
If UIDs repeat (like this is a child table with multiple records per UID), it would cover that case as well
If neither of these apply, you could dumb it down quite a bit.
The solution would look something like this:
Add an ID column that will be your numeric equivalent to the UID:
alter table test_table
add column id bigint
Create a sequence:
CREATE SEQUENCE test_id
create a cross-reference table (again, not necessary for the dumbed down version):
create table test_id_xref (
uid varchar(32) not null,
id bigint not null,
constraint test_id_xref_pk primary key (uid)
)
Then do a one-time update to assign a surrogate ID to each UID for both the cross-reference and actual tables:
insert into test_id_xref
with uids as (
select distinct uid
from test_table
)
select uid, nextval ('test_id')
from uids;
update test_table tt
set id = x.id
from test_id_xref x
where tt.uid = x.uid;
And finally, for all future inserts, create a trigger to assign the next value:
CREATE OR REPLACE FUNCTION test_table_insert_trigger()
RETURNS trigger AS
$BODY$
BEGIN
select t.id
from test_id_xref t
into NEW.id
where t.uid = NEW.uid;
if NEW.id is null then
NEW.id := nextval('test_id');
insert into test_id_xref values (NEW.uid, NEW.id);
end if;
return NEW;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
CREATE TRIGGER insert_test_table_trigger
BEFORE INSERT
ON test_table
FOR EACH ROW
EXECUTE PROCEDURE test_table_insert_trigger();
create one function which replace charter with blank which you not need in string,
CREATE FUNCTION replace_char(v_string VARCHAR(32) CHARSET utf8) RETURNS VARCHAR(32)
DETERMINISTIC
BEGIN
DECLARE v_return_string VARCHAR(32) DEFAULT '';
DECLARE v_remove_char VARCHAR(200) DEFAULT '1,2,3,4,5,6,7,8,9,0';
DECLARE v_length, j INT(3) DEFAULT 0;
SET v_length = LENGTH(v_string);
WHILE(j < v_length) DO
IF ( FIND_IN_SET( SUBSTR(v_string, (j+1), 1), v_remove_char ) = 0) THEN
SET v_return_string = CONCAT(v_return_string, SUBSTR(v_string, (j+1), 1) );
END IF;
SET j = j+1;
END WHILE;
RETURN v_return_string;
END$$
DELIMITER ;
Now you just nee to call this function in query
select uid, replace_char(uid) from test_table;
It will give you string what you need (bfaebfbbffde)
If you want to int number only i.e 13574238486817567941 then change value of variable, and also column datatype in decimal(50,0), decimal can stored large number and there is 0 decimal point so it will store int value as decimal.
v_remove_char = 'a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z';
Essentially I wish to create a trigger that keeps track and edits the date_created column of a specific row after every insert or update.
These are the columns in my table:
| customer_id | store_id | Quantity | date_created |
the customer_id and store_id together are the primary key of the table
What I have so far:
CREATE OR REPLACE TRIGGER date_trig
BEFORE INSERT ON customer_table
FOR EACH ROW
DECLARE
BEGIN
-- This is where I assume the date will be set or edited
END;
I am brand new to PL/SQL so I am struggling with the actual body of this trigger.
Also, do I have the structure of a trigger correctly formed?
Hi Please find sample code.
create or replace trigger emp_mod_date
before update or insert on emp
for each row
begin
:new.mdate := sysdate;
end;
Use DEFAULT SYSDATE on the colum date_created like already suggested
if you insist to use a trigger, just write :NEW.date_created := SYSDATE;
I have a workqueue table that has a workid column. The workID column has values that increment automatically. Is there a way I can run a query in the backend to insert a new row and have the workID column increment automatically?
When I try to insert a null, it throws error ORA01400 - Cannot insert null into workid.
insert into WORKQUEUE (facilitycode,workaction,description) values ('J', 'II', 'TESTVALUES')
What I have tried so far - I tried to look at the table details and didn't see any auto-increment. The table script is as follow
"WORKID" NUMBER NOT NULL ENABLE,
Database: Oracle 10g
Screenshot of some existing data.
ANSWER:
I have to thank each and everyone for the help. Today was a great learning experience and without your support, I couldn't have done. Bottom line is, I was trying to insert a row into a table that already has sequences and triggers. All I had to do was find the right sequence, for my question, and call that sequence into my query.
The links you all provided me helped me look these sequences up and find the one that is for this workid column. Thanks to you all, I gave everyone a thumbs up, I am able to tackle another dragon today and help patient care take a step forward!"
This is a simple way to do it without any triggers or sequences:
insert into WORKQUEUE (ID, facilitycode, workaction, description)
values ((select max(ID)+1 from WORKQUEUE), 'J', 'II', 'TESTVALUES')
It worked for me but would not work with an empty table, I guess.
To get an auto increment number you need to use a sequence in Oracle.
(See here and here).
CREATE SEQUENCE my_seq;
SELECT my_seq.NEXTVAL FROM DUAL; -- to get the next value
-- use in a trigger for your table demo
CREATE OR REPLACE TRIGGER demo_increment
BEFORE INSERT ON demo
FOR EACH ROW
BEGIN
SELECT my_seq.NEXTVAL
INTO :new.id
FROM dual;
END;
/
There is no built-in auto_increment in Oracle.
You need to use sequences and triggers.
Read here how to do it right. (Step-by-step how-to for "Creating auto-increment columns in Oracle")
ELXAN#DB1> create table cedvel(id integer,ad varchar2(15));
Table created.
ELXAN#DB1> alter table cedvel add constraint pk_ad primary key(id);
Table altered.
ELXAN#DB1> create sequence test_seq start with 1 increment by 1;
Sequence created.
ELXAN#DB1> create or replace trigger ad_insert
before insert on cedvel
REFERENCING NEW AS NEW OLD AS OLD
for each row
begin
select test_seq.nextval into :new.id from dual;
end;
/ 2 3 4 5 6 7 8
Trigger created.
ELXAN#DB1> insert into cedvel (ad) values ('nese');
1 row created.
You can use either SEQUENCE or TRIGGER to increment automatically the value of a given column in your database table however the use of TRIGGERS would be more appropriate. See the following documentation of Oracle that contains major clauses used with triggers with suitable examples.
Use the CREATE TRIGGER statement to create and enable a database trigger, which is:
A stored PL/SQL block associated with a table, a schema, or the
database or
An anonymous PL/SQL block or a call to a procedure implemented in
PL/SQL or Java
Oracle Database automatically executes a trigger when specified conditions occur. See.
Following is a simple TRIGGER just as an example for you that inserts the primary key value in a specified table based on the maximum value of that column. You can modify the schema name, table name etc and use it. Just give it a try.
/*Create a database trigger that generates automatically primary key values on the CITY table using the max function.*/
CREATE OR REPLACE TRIGGER PROJECT.PK_MAX_TRIGGER_CITY
BEFORE INSERT ON PROJECT.CITY
FOR EACH ROW
DECLARE
CNT NUMBER;
PKV CITY.CITY_ID%TYPE;
NO NUMBER;
BEGIN
SELECT COUNT(*)INTO CNT FROM CITY;
IF CNT=0 THEN
PKV:='CT0001';
ELSE
SELECT 'CT'||LPAD(MAX(TO_NUMBER(SUBSTR(CITY_ID,3,LENGTH(CITY_ID)))+1),4,'0') INTO PKV
FROM CITY;
END IF;
:NEW.CITY_ID:=PKV;
END;
Would automatically generates values such as CT0001, CT0002, CT0002 and so on and inserts into the given column of the specified table.
SQL trigger for automatic date generation in oracle table:
CREATE OR REPLACE TRIGGER name_of_trigger
BEFORE INSERT
ON table_name
REFERENCING NEW AS NEW
FOR EACH ROW
BEGIN
SELECT sysdate INTO :NEW.column_name FROM dual;
END;
/
the complete know how, i have included a example of the triggers and sequence
create table temasforo(
idtemasforo NUMBER(5) PRIMARY KEY,
autor VARCHAR2(50) NOT NULL,
fecha DATE DEFAULT (sysdate),
asunto LONG );
create sequence temasforo_seq
start with 1
increment by 1
nomaxvalue;
create or replace
trigger temasforo_trigger
before insert on temasforo
referencing OLD as old NEW as new
for each row
begin
:new.idtemasforo:=temasforo_seq.nextval;
end;
reference:
http://thenullpointerexceptionx.blogspot.mx/2013/06/llaves-primarias-auto-incrementales-en.html
For completeness, I'll mention that Oracle 12c does support this feature. Also it's supposedly faster than the triggers approach. For example:
CREATE TABLE foo
(
id NUMBER GENERATED BY DEFAULT AS IDENTITY (
START WITH 1 NOCACHE ORDER ) NOT NULL ,
name VARCHAR2 (50)
)
LOGGING ;
ALTER TABLE foo ADD CONSTRAINT foo_PK PRIMARY KEY ( id ) ;
Best approach: Get the next value from sequence
The nicest approach is getting the NEXTVAL from the SEQUENCE "associated" with the table. Since the sequence is not directly associated to any specific table,
we will need to manually refer the corresponding table from the sequence name convention.
The sequence name used on a table, if follow the sequence naming convention, will mention the table name inside its name. Something likes <table_name>_SEQ. You will immediately recognize it the moment you see it.
First, check within Oracle system if there is any sequence "associated" to the table
SELECT * FROM all_sequences
WHERE SEQUENCE_OWNER = '<schema_name>';
will present something like this
Grab that SEQUENCE_NAME and evaluate the NEXTVAL of it in your INSERT query
INSERT INTO workqueue(id, value) VALUES (workqueue_seq.NEXTVAL, 'A new value...')
Additional tip
In case you're unsure if this sequence is actually associated with the table, just quickly compare the LAST_NUMBER of the sequence (meaning the current value) with the maximum id of
that table. It's expected that the LAST_NUMBER is greater than or equals to the current maximum id value in the table, as long as the gap is not too suspiciously large.
SELECT LAST_NUMBER
FROM all_sequences
WHERE SEQUENCE_OWNER = '<schema_name>' AND SEQUENCE_NAME = 'workqueue_seq';
SELECT MAX(ID)
FROM workqueue;
Reference: Oracle CURRVAL and NEXTVAL
Alternative approach: Get the current max id from the table
The alternative approach is getting the max value from the table, please refer to Zsolt Sky answer in this same question
This is a simple way to do it without any triggers or sequences:
insert into WORKQUEUE (ID, facilitycode, workaction, description)
values ((select count(1)+1 from WORKQUEUE), 'J', 'II', 'TESTVALUES');
Note : here need to use count(1) in place of max(id) column
It perfectly works for an empty table also.