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Altering tables using SQL statements

Posted on 2006-07-13
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Last Modified: 2008-01-09
Hi there,

We have a web based product written in php utilizing a MS SQL database.  We have clients that host our software internally meaning when we have to send them updates to our software we are not able see their version of the database, meaning if one of our updates includes a database change we have to send them an update script as well that will do this.

That's all be fine up to now, however a bug has been discovered where the Precision of a numeric field was incorrect and so we have written an SQL statment that will change the precision of the field:

ALTER TABLE tablename ALTER COLUMN field_name DOUBLE PRECISION(5);

However we get an error:

The object 'DF__actionpla__statu__07020F21' is dependent on column 'status_percentage_complete'

We obviously need to remove this dependancy before executing the first statement, but we can't work out how to do this using an SQL statement.

Help much apreciated, and time is of the escence so maximum points available.

Tom
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Comment
Question by:jbclelland
10 Comments
 
LVL 11

Expert Comment

by:Ved Prakash Agrawal
ID: 17098468

TRY IT





ALTER TABLE [dbo].[acct_Contacts] DROP CONSTRAINT [DF__actionpla__statu__07020F21]

GO

ALTER TABLE tablename ALTER COLUMN field_name DOUBLE PRECISION(5);

GO

0
 
LVL 75

Expert Comment

by:Aneesh Retnakaran
ID: 17098511
Continuing from the above post ,

Run

sp_help 'urtablename'

first to see the constraints, then delete the constraints
,Once the constraints are deleted , dro p the table
0
 

Author Comment

by:jbclelland
ID: 17099121
Is the name 'DF__actionpla__statu__07020F21' always going to be consistant or could the name of it vary dependant on installation etc because we need to send this out to several clients.  If it could differ, can we search for all the depandcies of a particular table?

Tom
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LVL 27

Expert Comment

by:ptjcb
ID: 17099320
No, it may change. Because you are rolling this out to several clients you should make it a practice to always name the constraints - don't let SQL do it for you. You can do that in the CREATE TABLE statements.

I found this script here - http://www.sqlteam.com/item.asp?ItemID=2232 -  and it works well in identifying the constraints.
create view v_DEFAULT_CONSTRAINT
as select db_name() as CONSTRAINT_CATALOG ,t_obj.name as TABLE_NAME ,
user_name(c_obj.uid) as CONSTRAINT_SCHEMA ,c_obj.name as CONSTRAINT_NAME ,
col.name as COLUMN_NAME ,col.colid as ORDINAL_POSITION ,com.text as DEFAULT_CLAUSE
from sysobjects c_obj join syscomments com on c_obj.id = com.id join sysobjects t_obj
on c_obj.parent_obj = t_obj.id join sysconstraints con on c_obj.id = con.constid
join syscolumns col on t_obj.id = col.id and con.colid = col.colid where c_obj.uid = user_id()
and c_obj.xtype = 'D'

0
 

Author Comment

by:jbclelland
ID: 17099453
Thanks for that, however could you please give me some more information as to how I can use this code to help me out of the problem I have?

Tom.
0
 
LVL 27

Expert Comment

by:ptjcb
ID: 17100415
Ok, I  found a script here:http://midwestcoders.net/blogs/matt_mikulicz/archive/2005/11/10/183.aspx

It changes the default name to table and column name and drops the hex numbers at the end. I changed it to work through every table in a 2000 database (I would add the schema name to use it with 2005). You run this script and it will generate a text script - copy and paste it into a new QA and then run it to change the default names.

set quoted_identifier off
DECLARE
  @Exists     VARCHAR(200),
  @Begin      VARCHAR(100),
  @Print1     VARCHAR(500),
  @Drop       VARCHAR(200),
  @Print2     VARCHAR(500),
  @Add        VARCHAR(200),
  @End        VARCHAR(100),
  @TABLE_NAME VARCHAR(128)

DECLARE TN CURSOR FOR
SELECT table_name FROM information_schema.COLUMNS
WHERE column_default IS NOT NULL

--SELECT @TABLE_NAME = 'OpenTransactionsHistory'
OPEN TN

FETCH NEXT FROM TN INTO @TABLE_NAME

WHILE @@FETCH_STATUS = 0
BEGIN

DECLARE AlterDefault_Cursor CURSOR FOR
SELECT

    "if exists(select * from dbo.sysobjects where id = object_id(N'[dbo].[" + c_obj.name + "]') and OBJECTPROPERTY(id, N'IsDefaultCnst') = 1)" AS [exists],
     'BEGIN' AS [begin],
     "PRINT '   Dropping " + c_obj.name + "'" AS [Print1],
     'ALTER TABLE [dbo].[' + t_obj.name + '] DROP CONSTRAINT ' + c_obj.name + '' AS [Drop],
     "PRINT '   Creating DF_" + t_obj.name + '_' + col.name  + "'" AS [Print2],
     'ALTER TABLE [dbo].[' + t_obj.name + '] ADD CONSTRAINT DF_' + t_obj.name + '_' + col.name  + ' DEFAULT' + com.text + ' FOR ' + col.name + '' AS [Add],
     'END' AS [end]

FROM sysobjects c_obj
INNER JOIN syscomments com ON c_obj.id = com.id
INNER JOIN sysobjects t_obj ON c_obj.parent_obj = t_obj.id
INNER JOIN sysconstraints con ON c_obj.id = con.constid
INNER JOIN syscolumns col ON t_obj.id = col.id
  AND con.colid = col.colid
WHERE c_obj.xtype = 'D'
AND   t_obj.name = @TABLE_NAME

OPEN AlterDefault_Cursor

FETCH NEXT FROM AlterDefault_Cursor
   INTO @Exists, @Begin, @Print1, @Drop, @Print2, @Add, @End

WHILE @@FETCH_STATUS = 0
  BEGIN

    PRINT @Exists
    PRINT '   ' + @Begin
    PRINT ' ' + "PRINT ''"
    PRINT ' ' + @Print1
    PRINT ' ' + @Drop
    PRINT ' ' + @Print2
    PRINT ' ' + @Add
    PRINT '   ' + @End
    PRINT ''

    FETCH NEXT FROM AlterDefault_Cursor
        INTO @Exists, @Begin, @Print1, @Drop, @Print2, @Add, @End

  END

CLOSE AlterDefault_Cursor
DEALLOCATE AlterDefault_Cursor

FETCH NEXT FROM TN INTO @TABLE_NAME
END

CLOSE TN
DEALLOCATE TN
set quoted_identifier on

0
 

Author Comment

by:jbclelland
ID: 17100854
Thanks once again, however I do not have access to a client's machine, and we do not want them to see things like this, so I really need a solution that will work from a web based environment rather than using Query Analyser or Enterprise Manager.

Tom
0
 
LVL 27

Expert Comment

by:ptjcb
ID: 17100896
Oh, sorry.  You might have a better chance of finding a front-end web solution using the particular web area or language area. This section deals with writing t-sql queries and database maintenance questions.
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Accepted Solution

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CetusMOD earned 0 total points
ID: 17631692
PAQed with no points refunded (of 500)

CetusMOD
Community Support Moderator
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