A declarative mechanism such as a check or foreign key that enforces some data integrity rule in a database.

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1answer
72 views

SQL Server - Is it possible to forbid creation of default constraint name?

I was having a looking on this article about default constraints and I have a question. Is there a configuration in SQL Server 2008 that forbid naming creation of new default constraints declared ...
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5answers
15k views

When should I use a unique constraint instead of a unique index?

When I want a column to have distinct values, I can either use a constraint create table t1( id int primary key, code varchar(10) unique NULL ); go or I can use a unique index create table t2( id ...
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1answer
2k views

Cannot add foreign key constraint while creating table

My Error Code is 1215 which finds problem with the foreign key constraint. I know all fields are the same data types. I can't see where the problem is. Any help would be much appreciated! Thanks! ...
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1answer
2k views

How to insert data into tables which reference each other?(MySQL)

I'm a student and right now I have a problem that I couldn't solve by myself(after searching on the Internet). I'm not going to give my «homework» because I want to learn what I'm doing but I will ...
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2answers
202 views

SQL Check Constraint that requires a not null value in a column based on the value of another column

I have a table with the following two columns OnSite BIT NOT NULL ClientId INT NULL I want to add a constraint that requires ClientId to be NOT NULL when OnSite is true(1). I could not find ...
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1answer
626 views

Complex constraint across all data in a table

We have a table to record processing that occurs on a system and we need to ensure that only a single row has an 'in process' status. I want to ensure that the result of this is always either zero or ...
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2answers
973 views

Primary key within JSON data in Postgresql

I have a table t, with a column called json, of type JSON. Within the JSON there is a natural key: > SELECT json->'id' AS id FROM t LIMIT 1; id ...
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1answer
159 views

Alternatives to NULL for missing data [duplicate]

I am using PostgreSQL and trying to write value constraints. Is it possible to record missing data as distinct from NULL values in a numeric field without using an arbitrary numeric value? For many ...
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1answer
30 views

Require uniqueness with group by

I'm not sure how to couch this question. I have a table that has multiple columns including an id column, a foreign key column 'JobId', and a 'GxpId' column. I have a requirement that a 'JobId' can ...
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3answers
2k views

Listing indexes and constraints

I am looking at a SQL Server database for an application I have inherited. I have not looked into SQL Server for approximately 10 years, so please bear with me. The database table I am looking at has ...
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1answer
317 views

How do I validate all my constraints in postgresql?

It seems like I have been bitten by the first bug described in the release notes of postgresql 9.3.4: http://www.postgresql.org/docs/devel/static/release-9-3-4.html I now have e.g. duplicate primary ...
2
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1answer
82 views

Confused on how a value gets added with the DEFAULT constraint

A recent definition I've read about Default Constraints: DEFAULT is specified for a column to assign a column a specific value if no value is specified when a row is added. I believe I've seen code ...
2
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1answer
40 views

How can I model and enforce constraints on a categorical item contained in a collection?

Scenario: There is a collection of items where each item belongs to 1 category. There is a collection of buckets which may contain at most 1 item from each category. Oh, and an item may belong to at ...
2
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1answer
195 views

Two relations to same table in SQL Server

I've got two tables. When I delete a row in Table1, I want to set the ID of that row in all the rows of Table2 to NULL. I've got two relationships on Table1. The problem is: I can only set one delete ...
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3answers
9k views

check constraint does not work?

I have the following table. create table test ( id smallint unsigned AUTO_INCREMENT, age tinyint not null, primary key(id), check (age<20) ); The problem is that the CHECK ...
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0answers
53 views

Two different unique constraints for 1 table?

I must enforce uniqueness within my table, But I cannot seem to find anywhere online(mysql manual,forums,stack overflow) talk about two unique constraints within one table. Why you might ask I need ...
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1answer
32 views

design DB review and check constraint for postalcode help?

Hi. I created this database to just to sharpen my skill. I have one Question - when I create I make the FOREIGN KEY personID in Addresses table but I changed it to be AddressID in Persons table ...
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0answers
841 views

User defined table type with a check constraint

I have a user defined table type where I want to make sure that a certain column is within a given range. This range however is defined in another table. So I thought I can use a check constraint on ...
2
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0answers
207 views

Postgres 9.3 - deletes terribly slow for 10 minutes after dropping indexes/constraints

If I run a script which drops indexes (17 of them, CONCURRENTLY makes no difference except that without it I get the occasional deadlock), then constraints (20 constraints on 18 tables) and then run a ...
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1answer
4k views

MYSQL - Problem with foreign keys on same table

In Mysql 5.5, I have a table, in which I store some informations about "events".. In order to have a chronological order, I made two columns that reference to the previous and to the next event. So I ...
2
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1answer
144 views

Does a SQL server unique constraint partially or fully fail a multi-row write?

If some rows of a writing query fails a unique constraint, will only those writes be rejected, or will the entire query fail?
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0answers
122 views

Error adding constraint foreign key to bridge table

Hi there I am fairly new to sql development. I am current following the head first into mysql book and is on chapter 6. On chapter 6 there is a table in third normal form but it does not contains the ...
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2answers
143 views

Accept null value on parent column in multipart relationship

EDIT: I've come up with one poor solution (below) that requires some denormalization, but does avoid the risks of UDFs in CHECK constraints. I would appreciate your help if you have a better answer. ...
2
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1answer
1k views

Two-column foreign key constraint only when third column is NOT NULL

Given the following tables: CREATE TABLE verified_name ( id SERIAL PRIMARY KEY, name TEXT NOT NULL, email TEXT NOT NULL, UNIQUE (name, email) ); CREATE ...
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0answers
1k views

CHECK constraint ignored during INSERT SELECT

I have the following 2 tables (simplified): CREATE TABLE dbo.[StagingTable] ( HostName [nvarchar] (max) NULL ,UserName [nvarchar] (max) NULL ,AccountType [nvarchar] (max) NULL ) CREATE TABLE ...
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1answer
353 views

On which filegroup will constraints be created by default when adding them to a table on a filegroup and how should they be separeated?

We have multiple filegroups, that look something like this: PRIMARY (default) app_data app_index When I create a table on filegroup app_data CREATE TABLE Person ( [PersonID] INT NOT NULL ...
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1answer
32 views

Conditional when creating a domain

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 ...
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1answer
101 views

Create constraint for stopping mass update to a table

I want to create a constraint so that if more than 5 rows in a table are getting updated with an UPDATE statement it should warn the user / block the query.
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1answer
178 views

Unique constraint on multiple nullable columns Sql Server

We have a PriceCombo table with the following columns: id (not null), a_id(null),b_id(null),c_id(null), discount(not null). We are using this table to figure out which price to assign various combos ...
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0answers
283 views

postgresql multi column unique or check constraint

First a word of pleading. To say I am a newbie to postgresql would be an insult to the newbies! I have been working on this for only a day or so. I have found several questions on this site, and ...
2
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1answer
107 views

How can I change Referential Integrity from a Unique Key Constraint to a Primary Key?

(without dropping foreign keys) I have migrated a SQL Server CE database to SQL Server 2012, however, referential integrity was enforced via unique key constraints on the surrogate INT identity ...
2
votes
1answer
230 views

PostgreSQL 9.2 tstzrange null/infinity CONSTRAINT CHECK

I'd like to limit a PostgreSQL 9.2 tstzrange to valid dates at both ends. No NULLs nor 'infinity'. Various revisions of this SQL isn't constraining '-/+infinity' input: CREATE TABLE bill ( id ...
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0answers
736 views

PostgreSQL Cascade Delete not working

What am I missing here? I have two tables: CREATE TABLE source ( "sourceid" serial, "state" character varying(255) REFERENCES states (state), "leadtime" character varying(255), CONSTRAINT ...
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1answer
76 views

What can do a table constraint that a column constraint can't do? [closed]

Had an exam today. One question disturbed me: Q: What can a table constraint do that a column constraint can't do? A: My answer was that only a table constraint can declare a composite primary key. ...
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1answer
99 views

Constrains relationship

I have the following design. Each user has it's own contacts, it's own hosts and assign those to a domain which belongs only to him. I want to insure that the host you assign to the domain belongs ...
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1answer
3k views

Oracle, Create table with inline constraint declarations using a different tablespace

I have two questions about inline constraints declarations for Oracle tables: Is it a bad practice? If so, why? How could one declare a different tablespace for the primary key and index like it's ...
1
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1answer
745 views

MySQL: update instead of delete if foreign key constraint?

I have a bit of a strange question. I know about insert on duplicate key update. My question is, is there something similar for deletes that fail because of foreign key constraints? For example: ...
2
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2answers
172 views

MySQL - unique constraints design

I am using MySQL and looking to solve a problem with relational data. I am not sure it is possible but wanted to ask the community. Please consider the diagram: I would like to add a unique ...
2
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3answers
3k views

Unique constraint across two columns

I need to add a constraint with two columns that says if any given value is present in one of the columns, then: 1) It cannot be duplicated in the same column. 2) It cannot be duplicated in the ...
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2answers
178 views

Constraint on Composite Type

How can I create a constraint on a sub-field of composite type? Pseudocode create type axis( major_axis float, minor_axis float, angle float constraint angle_constraint check(angle ...
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1answer
879 views

Constraint based rules engine

I am evaluating software systems which configure products that tout constraint based versus rules based engines. Can someone explain (with maybe an example or two) to a non-expert what the difference ...
2
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2answers
77 views

Lock hints on preconditions

Assuming for a moment that FK references are not available, what lock hints should be placed on the preconditions of the following example to prevent deadlocks and inconsistent data? (This is a ...
2
votes
1answer
2k views

prevent MySQL Workbench to add index for foreignkey constraint when it is first part of primary

I know for each foreign key we should make an index on its column, But it is not necessary when that column in first part of PRIMARY index. MySQL accepts this query: CREATE TABLE IF NOT EXISTS ...
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1answer
321 views

MySQL import LOCK doesn't prevent PRIMARY key issues

I am using Django and only want to backup mysql data (not it's structure; Django will do that, and it will otherwise mess up Django-South's migration checks). Some info; my tables are almost all ...
2
votes
2answers
80 views

Postgresql constrains on FK

I am trying to design a (part of a) database which has to accomplish the following: There is a students table, containing a bunch of students. There are educations in the database. Each student can ...
5
votes
2answers
2k views

Transactions, references and how to enforce double entry bookkeeping? (PG)

Double entry bookkeeping is a set of rules for recording financial information in a financial accounting system in which every transaction or event changes at least two different nominal ...
1
vote
1answer
123 views

How can I achieve a unique constraint with two fields? [duplicate]

I have a table with e.g. Name and IsDeleted fields. I want to add a row constraint so that only one Name value can have IsDeleted as 'false'. There can be many duplicate Name values, but they must all ...
0
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0answers
120 views

Why does mysql show Primary key constraint on a View?

As far as I know views cannot have a primary key. However the result of SELECT FROM KEY_COLUMN_USAGE says differ. PRIMARY | S_MOBILE_ITEM_VIEW | ID | ...
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2answers
3k views

Constraints based on other columns

Is it possible to limit what values are allowed in a coulumn based off of other values in the row? For example, my table: ID Test_mode Active -- --------- ------ 1 1 Null 2 0 ...
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1answer
413 views

Creating a partial unique constraint for MySQL

I have the same question as asked in a previous post: PostgreSQL multi-column unique constraint and NULL values. But the solution there is not applicable as I am using MySQL instead of PostgreSQL. My ...