SQL Server – Unable to Save Database Diagrams

database-diagramssql server

I'm trying to save a database diagram but I'm getting an error. How can I fix this?

Cannot insert the value NULL into column 'diagram_id', table
'SOFT.dbo.sysdiagrams'; column does not allow nulls. INSERT fails.
The statement has been terminated.
The 'sp_creatediagram' procedure attempted to return a status of NULL, which is not allowed.
A status of 0 will be returned instead. (.Net SqlClient Data Provider)

Best Answer

Hard to suggest a more specific fix or suggest a cause given that we have no background on how your system got into this state, what you did prior to trying to create the first diagram, if you have successfully created diagrams in the past, or even what version of SQL Server you're using. It sounds like your sysdiagrams table somehow lost the IDENTITY property on the diagram_id column. Do this:

DROP TABLE dbo.sysdiagrams;
GO
CREATE TABLE [dbo].[sysdiagrams]
(
    [name] [sysname] NOT NULL,
    [principal_id] [int] NOT NULL,
    [diagram_id] [int] IDENTITY(1,1) PRIMARY KEY,
    [version] [int] NULL,
    [definition] [varbinary](max) NULL,
    CONSTRAINT [UK_principal_name] UNIQUE ([principal_id],[name])
);

GO
EXEC sys.sp_addextendedproperty 
  @name=N'microsoft_database_tools_support', 
  @value=1 , 
  @level0type=N'SCHEMA',
  @level0name=N'dbo', 
  @level1type=N'TABLE',
  @level1name=N'sysdiagrams';
GO

This will of course lose any diagrams you were previously able to save.

(After performing a search it saddened me to see that many people suggest as a fix to make the default for this column 0. This is great after you create one diagram but falls apart for multiple reasons once you try to create a second one.)

Related Solutions

Sql-server – TSQL change column constraint between null and not null

When trying to return the column back to NOT NULL SQL Server immediately checks the constraint, which fails because the rows for that column were set to NULL.

For an existing column, you have to update the table to remove any NULL values before you can set it as NOT NULL.

SQL Server – Does the Inserted Table Contain Identity Values?

The error is caused by attempting to insert AuditTerms when there is no corresponding primary key in TermKeys. After creating the table schema and trigger in tempdb and inserting a few records in TermKeys, I was able to reproduce it by issuing a DELETE twice on the same TermID:

DELETE FROM TermKeys
WHERE TermID = 1

DELETE FROM TermKeys
WHERE TermID = 1

gives me:

Msg 515, Level 16, State 2, Procedure TRG_TermKeys_AuditTerms_IUD, Line 15 Cannot insert the value NULL into column 'TermID', table 'tempdb.dbo.AuditTerms'; column does not allow nulls. INSERT fails. The statement has been terminated.

Something in the application code may be running the query twice; I can't see any other way to get a null value. The best way to avoid the error is to add a precautionary check of @@ROWCOUNT at the beginning of the trigger, since it will return the total number of rows affected by the DML statement that fired it.

ALTER TRIGGER [dbo].[TRG_TermKeys_AuditTerms_IUD] ON [dbo].[TermKeys] 
AFTER INSERT, UPDATE, DELETE NOT FOR REPLICATION AS
BEGIN
  -- If the trigger was fired but no rows were affected, do nothing 
  IF @@ROWCOUNT = 0
    RETURN;
  SET NOCOUNT ON;
  DECLARE @termid int;
  IF EXISTS(SELECT * FROM Deleted) SELECT @termid = TermID FROM Deleted;
  IF EXISTS(SELECT * FROM Inserted) SELECT @termid = TermID FROM Inserted;
  IF EXISTS(SELECT TermID FROM AuditTerms WHERE (TermID = @termid))
  BEGIN
    UPDATE AuditTerms SET UpdatedAt = getdate() WHERE (TermID = @termid);
  END
  ELSE
  BEGIN
    INSERT INTO AuditTerms (TermID, UpdatedAt) VALUES (@termid, getdate());
  END;
END;

Best Answer

Related Solutions

Sql-server – TSQL change column constraint between null and not null

SQL Server – Does the Inserted Table Contain Identity Values?

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