I have a little doubt, I want to create a table that had a date that can't be bigger the 2012/12/31, i searched on google but only had exemples on SELECT. I'm gonna put an example:
CREATE TABLE example(
IDExample number (8) primary key,
DateExample date // Here i want to put that condition, is it possible?
);
If you're using SQL Server you can add check contraint on the column in the following way.
ALTER TABLE dbo.example ADD CONSTRAINT CK_DateExample
CHECK (DateExample < '20130101')
If you're using Oracle, the syntax is very similar:
ALTER TABLE dbo.example ADD CONSTRAINT CK_DateExample
CHECK (DateExample < DATE '2013-01-01')
Related
I have created one table in PL SQL Developer.
CREATE TABLE Patient_List
(
Patient_ID number NOT NULL,
Patient_Name varchar(50) NOT NULL,
Patient_Address varchar(100) NULL,
App_Date date NULL,
Descr varchar(50),
CONSTRAINT patient_pk PRIMARY KEY(Patient_ID)
);
I want to auto increment Patient_ID, I tried altering the table and modifying the Patient_ID column but it's showing an error "invalid ALTER TABLE option"
ALTER TABLE Patient_List
MODIFY Patient_ID NUMBER NOT NULL GENERATED ALWAYS AS IDENTITY;
Please help, Thanks in advance.
This is not possible.
Oracle 10g didn't even have identity columns, they were introduced in Oracle 12.1
But even with a current Oracle version, you can't convert a regular column to an identity column. You would need to add a new one.
Before identity columns, the usual way was to create a sequence and a trigger to populate the column.
See here: How to create id with AUTO_INCREMENT on Oracle?
If anybody wants to modify existing column as auto_increment use this three lines
alter table Product drop column test_id;
create sequence Product_test_id_seq INCREMENT BY 1 nocache;
alter table Product add test_id Number default Product_test_id_seq.nextval not null;
I'm trying to create a constrain to check the record is no greater than 2016.
Here is the record in my database
Here is my query:
ALTER TABLE SIGHTINGS
ADD CONSTRAINT CK_SIGHTING_DATE
CHECK (SIGHTING_DATE <=TO_DATE('01-JAN-16'));
But I got an error says: ERROR at line 1:
ORA-02436: date or system variable wrongly specified in CHECK
constraint.
I've checked some similar questions on this website but there solutions doesn't solve my problem.
One option is to use the extract() function as you just want to check for the year:
ALTER TABLE SIGHTINGS
ADD CONSTRAINT CK_SIGHTING_DATE
CHECK (extract(year from SIGHTING_DATE) < 2016);
or use an ANSI date literal:
ALTER TABLE SIGHTINGS
ADD CONSTRAINT CK_SIGHTING_DATE
CHECK (SIGHTING_DATE < date '2016-01-01');
you have make in date specifcation
ALTER TABLE SIGHTINGS
ADD CONSTRAINT CK_SIGHTING_DATE
CHECK (SIGHTING_DATE <=
/*TO_DATE('01-JAN-16','DD-MON-YY') as I was pointed your should specify 4 digits for year*/
TO_DATE('01-JAN-2016','DD-MON-YYYY'));
or
ALTER TABLE SIGHTINGS
ADD CONSTRAINT CK_SIGHTING_DATE
CHECK (SIGHTING_DATE <=DATE'2016-01-01');
another one things its what do you mean when you say "no greater than 2016"
Your check alow dates in 01-jan-2016 but not allow 02-jan-2016.
If you would like to include whole 2016 year write
SIGHTING_DATE < DATE'2017-01-01'
or
trunc(SIGHTING_DATE,'yy') <=DATE'2016-01-01'
I want to ensure that only the values 'Expert', 'Average' or 'Adequate' are entered into the levelOfExpertise column of this table, however whenever I do try an enter one of those values, it returns an error saying the value entered is too short. Here is the create table query for this particular table. The the column I am referring to is levelOfExpertise:
CREATE TABLE MusicianInstrument
(
musicianNo varchar(5) not null
CONSTRAINT MI_PK1 REFERENCES Musician(musicianNo),
instrumentName varchar(50) not null
CONSTRAINT MI_PK2 REFERENCES Instrument(instrumentName),
levelOfExpertise varchar(50),
CONSTRAINT levelOfExpertise CHECK (levelOfExpertise = 'Expert', 'Adequate', 'Avergage'),
PRIMARY KEY(musicianNo,instrumentName)
);
Any ideas how I can ensure only those three values (Expert, Adequate or Average) can be entered?
Thanks
Use the IN operator
CHECK (levelOfExpertise IN ('Expert','Adequate','Avergage'))
Try to change your CHECK constraint as following:
CONSTRAINT levelOfExpertise CHECK (levelOfExpertise IN ('Expert','Adequate','Avergage'))
I suppose that you use sql server as RDBMS.
Okay no seriously, if a PostgreSQL guru can help out I'm just getting started.
Basically what I want is a simple table like such:
CREATE TABLE schema.searches
(
search_id serial NOT NULL,
search_query character varying(255),
search_count integer DEFAULT 1,
CONSTRAINT pkey_search_id PRIMARY KEY (search_id)
)
WITH (
OIDS=FALSE
);
I need something like REPLACE INTO for MySQL. I don't know if I have to write my own procedure or something?
Basically:
check if the query already exists
if so, just add 1 to the count
it not, add it to the db
I can do this in my php code but I'd rather all that be done in postgres C engine
You have to add a unique constraint first.
ALTER TABLE schema.searches ADD UNIQUE (search_query);
The insert/replace command looks like this.
INSERT INTO schema.searches(search_query) VALUES ('a search query')
ON CONFLICT (search_query)
DO UPDATE SET search_count = schema.searches.search_count + 1;
This is probably a simple answer but I can't find it. I have a table with a column of integers and I want to ensure that when a row is inserted that the value in this column is greater than zero. I could do this on the code side but thought it would be best to enforce it on the table.
Thanks!
I was in error with my last comment all is good now.
You can use a check constraint on the column. IIRC the syntax for this looks like:
create table foo (
[...]
,Foobar int not null check (Foobar > 0)
[...]
)
As the poster below says (thanks Constantin), you should create the check constraint outside the table definition and give it a meaningful name so it is obvious which column it applies to.
alter table foo
add constraint Foobar_NonNegative
check (Foobar > 0)
You can get out the text of check constraints from the system data dictionary in sys.check_constraints:
select name
,description
from sys.check_constraints
where name = 'Foobar_NonNegative'
Create a database constraint:
ALTER TABLE Table1 ADD CONSTRAINT Constraint1 CHECK (YourCol > 0)
You can have pretty sophisticated constraints, too, involving multiple columns. For example:
ALTER TABLE Table1 ADD CONSTRAINT Constraint2 CHECK (StartDate<EndDate OR EndDate IS NULL)
I believe you want to add a CONSTRAINT to the table field:
ALTER TABLE tableName WITH NOCHECK
ADD CONSTRAINT constraintName CHECK (columnName > 0)
That optional NOCHECK is used to keep the constraint from being applied to existing rows of data (which could contain invalid data) & to allow the constraint to be added.
Add a CHECK constraint when creating your table
CREATE TABLE Test(
[ID] [int] NOT NULL,
[MyCol] [int] NOT NULL CHECK (MyCol > 1)
)
you can alter your table and add new constraint like bellow.
BEGIN TRANSACTION
GO
ALTER TABLE dbo.table1 ADD CONSTRAINT
CK_table1_field1 CHECK (field1>0)
GO
ALTER TABLE dbo.table1 SET (LOCK_ESCALATION = TABLE)
GO
COMMIT