All Questions
Tagged with constraint ddl
16 questions
3
votes
2
answers
299
views
Why does MySQL generate a `key` statement in DDL for composite primary keys?
I am using MySQL version 8.3.0.
I can create a “many to many” relationship between persons and teams tables with the following SQL statements:
create table persons (
id bigint not null,
last_name ...
- 356
3
votes
1
answer
2k
views
Making a column unmodifiable/non-updatable after its row's initial creation?
What is the most idiomatic way to make a column unmodifiable/non-updatable after its initial creation via INSERT in Oracle?
CREATE TABLE my_table (
id NUMBER NOT NULL CONSTRAINT ...
user68575
4
votes
2
answers
339
views
Advantages to column constraints over table constraints
Is there any advantages whatsoever, other than style to writing this,
CREATE TABLE foo (
a int PRIMARY KEY,
b int
);
And then,
CREATE TABLE bar (
a int REFERENCES foo,
c int
);
Over,
...
- 64.7k
8
votes
4
answers
406
views
Can I specify a name for the index which SQL Server creates for my unique constraint?
In SQL Server I deploy a table with a UNIQUE constraint:
CREATE TABLE [dbo].[Something] (
[IdentityId] UNIQUEIDENTIFIER UNIQUE NOT NULL DEFAULT NEWID()
-- Whatever else...
)
and this makes ...
- 1,331
1
vote
1
answer
1k
views
How to add constraint on a varchar column to have at least one non numeric character
I am trying to implement some constraints on tables so that there is no tampering of the data from what is expected.
One of the constraints is on a varchar column. It should at least contain one non-...
- 183
4
votes
2
answers
10k
views
SQL Error: OA-12991 - Unable to Drop a Column after removing all referenced Multi-Column constraints
I am new to Oracle DB and am in need of some help. I would like to drop a specific column but i am getting a specific error. The issue specifically is:
SQL Error: ORA-12991: column is reference ...
- 143
8
votes
1
answer
24k
views
The ALTER TABLE statement conflicted with the CHECK constraint
I need to check datecom is less than datelivr
create table Commande
(
Numcom int identity primary key,
Datecom date,
Datelivr date,
Codecli int foreign key references clients (Codecli)
)
alter ...
- 83
32
votes
3
answers
15k
views
Constraint to enforce "at least one" or "exactly one" in a database
Say we have users and each user can have multiple email addresses
CREATE TABLE emails (
user_id integer,
email_address text,
is_active boolean
)
Some sample rows
user_id | email_address | ...
- 825
1
vote
2
answers
918
views
Default constraint issue
I have a table TempTable with one column having a default constraint
ALTER TABLE [dbo].[TempTable]
ADD CONSTRAINT [DF_TempTable_Version]
DEFAULT ((1)) FOR [Version]
Version is defined as decimal ...
- 137
3
votes
4
answers
8k
views
Find constraint disabled in SQL Server
I'm doing an audit of constraints in SQL Server.
How to find all constraints that are not enabled?
This, after using the next declaration:
alter table mytable nocheck constraint all
- 449
0
votes
1
answer
192
views
What does a CONSTRAINT have to do with my unique index?
I have to indexes on my table. The first was created by Django and the second by me. I'm not completely certain what the extra CONSTRAINT means in the first index and am wondering how I would change ...
- 355
37
votes
2
answers
85k
views
How do I drop all constraints from all tables?
I want to drop all default constraints, check constraints, unique constraints, primary keys and foreign keys from all tables in a SQL Server database. I know how to get all the constraint names from ...
- 182k
5
votes
1
answer
15k
views
Check constraint references another column in same table
I have this table but check constraint is throwing me an error:
Column CHECK constraint for column 'MedicamentRegulated' references another column, table 'Medicaments'.
I've seen this as allowed ...
user37362
60
votes
2
answers
61k
views
MATCH FULL vs MATCH SIMPLE in foreign key constraints
I've noticed the clauses MATCH SIMPLE and MATCH FULL in phpPgAdmin, but I can't find a description in the docs.
The default is MATCH SIMPLE. How do they function?
user32234
1
vote
2
answers
210
views
Making a domain conditional on other values in the table
How can I define or change a domain based on another attribute value?
F.e. domain for salary is a numeric value > 500. But if a date the person was hired > January 1st, 2013, then the salary must be >...
- 113
7
votes
1
answer
215
views
Is there anything a table-level constraint declaration can do that a column-level one can not do?
Had an exam today. One question disturbed me:
What can a table-level constraint do that a column-level constraint can't do?
My answer was that only a table-level constraint declaration permits ...
