Sql – The ALTER TABLE statement conflicted with the FOREIGN KEY constrain

sqlsql servertsql

I'm kind of new to scripting in SQL and I have encountered an error in one of my scripts.
The problematic section is:

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE dbo.WorkspaceSettings
(
    Id INT NOT NULL IDENTITY PRIMARY KEY ,
        ReportColorRGB1 VARCHAR(15) NOT NULL DEFAULT '61,105,138' ,
    ReportColorRGB2 VARCHAR(15) NOT NULL DEFAULT '180,210,121' 
)

GO

ALTER TABLE Workspace ADD WorkspaceSettingsId int NOT NULL default 1;

GO
ALTER TABLE Workspace
ADD CONSTRAINT FK_WorkspaceSettings_Workspace
FOREIGN KEY (WorkspaceSettingsId)
REFERENCES WorkspaceSettings(Id);
GO

And receive the following error message:

Msg 547, Level 16, State 0, Line 1
The ALTER TABLE statement conflicted with the FOREIGN KEY constraint "FK_WorkspaceSettings_Workspace". The conflict occurred in database "ClearRisk2_0", table "dbo.WorkspaceSettings", column 'Id'.

Can someone please tell me where I'm going wrong?

Best Answer

The default value of 1 that you've specified for the Workspace.WorkspaceSettingsId column does not yet exist in your WorkspaceSettings table, hence the FK violation.

Syntax:

ALTER TABLE {TABLENAME} 
ADD {COLUMNNAME} {TYPE} {NULL|NOT NULL} 
CONSTRAINT {CONSTRAINT_NAME} DEFAULT {DEFAULT_VALUE}
WITH VALUES

Example:

ALTER TABLE SomeTable
        ADD SomeCol Bit NULL --Or NOT NULL.
 CONSTRAINT D_SomeTable_SomeCol --When Omitted a Default-Constraint Name is autogenerated.
    DEFAULT (0)--Optional Default-Constraint.
WITH VALUES --Add if Column is Nullable and you want the Default Value for Existing Records.

Notes:

Optional Constraint Name:
If you leave out CONSTRAINT D_SomeTable_SomeCol then SQL Server will autogenerate
a Default-Contraint with a funny Name like: DF__SomeTa__SomeC__4FB7FEF6

Optional With-Values Statement:
The WITH VALUES is only needed when your Column is Nullable
and you want the Default Value used for Existing Records.
If your Column is NOT NULL, then it will automatically use the Default Value
for all Existing Records, whether you specify WITH VALUES or not.

How Inserts work with a Default-Constraint:
If you insert a Record into SomeTable and do not Specify SomeCol's value, then it will Default to 0.
If you insert a Record and Specify SomeCol's value as NULL (and your column allows nulls),
then the Default-Constraint will not be used and NULL will be inserted as the Value.

Notes were based on everyone's great feedback below.
Special Thanks to:
@Yatrix, @WalterStabosz, @YahooSerious, and @StackMan for their Comments.

Sql – How to list all foreign keys referencing a given table in SQL Server

Not sure why no one suggested but I use sp_fkeys to query foreign keys for a given table:

EXEC sp_fkeys 'TableName'

You can also specify the schema:

EXEC sp_fkeys @pktable_name = 'TableName', @pktable_owner = 'dbo'

Without specifying the schema, the docs state the following:

If pktable_owner is not specified, the default table visibility rules of the underlying DBMS apply.

In SQL Server, if the current user owns a table with the specified name, that table's columns are returned. If pktable_owner is not specified and the current user does not own a table with the specified pktable_name, the procedure looks for a table with the specified pktable_name owned by the database owner. If one exists, that table's columns are returned.

Best Answer

Related Solutions

Sql – Add a column with a default value to an existing table in SQL Server

Syntax:

Example:

Notes:

Sql – How to list all foreign keys referencing a given table in SQL Server

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