Sql – Can’t change table design in SQL Server 2008

sqlsql serversql-server-2008

I created a table tbl_Candidate, but I forgot to set the primary key to the table and I saved it without primary key.

Next time I'm going to set primary key in SQL Server 2008 Express, I get a message like I have to drop the table and recreate when I'm going to save the table with primary key changes.

This is the message that pops up when I'm trying to save changes in the table:

Saving changes is not permitted. The changes you have made require
that the following tables to dropped and recreate. You have either made
changes to the table that can't be recreate or enable the option
prevent saving changes that require the tables to be recreate

I'm logged into SQL Server with Windows authentication, server type as database engine and Server name as .\SQLExpress.

Please give me a way to correct this problem or way to change the settings of the SQL Server.

Best Answer

The answer is on the MSDN site:

The Save (Not Permitted) dialog box warns you that saving changes is not permitted because the changes you have made require the listed tables to be dropped and re-created.

The following actions might require a table to be re-created:

Adding a new column to the middle of the table

Dropping a column

Changing column nullability

Changing the order of the columns

Changing the data type of a column

EDIT 1:

Additional useful informations from here:

To change the Prevent saving changes that require the table re-creation option, follow these steps:

Open SQL Server Management Studio (SSMS).

On the Tools menu, click Options.

In the navigation pane of the Options window, click Designers.

Select or clear the Prevent saving changes that require the table re-creation check box, and then click OK.

Note If you disable this option, you are not warned when you save the table that the changes that you made have changed the metadata structure of the table. In this case, data loss may occur when you save the table.

Risk of turning off the "Prevent saving changes that require table re-creation" option

Although turning off this option can help you avoid re-creating a table, it can also lead to changes being lost. For example, suppose that you enable the Change Tracking feature in SQL Server 2008 to track changes to the table. When you perform an operation that causes the table to be re-created, you receive the error message that is mentioned in the "Symptoms" section. However, if you turn off this option, the existing change tracking information is deleted when the table is re-created. Therefore, we recommend that you do not work around this problem by turning off the option.

Settings, screen shot

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-server – How to check if a column exists in a SQL Server table

SQL Server 2005 onwards:

IF EXISTS(SELECT 1 FROM sys.columns 
          WHERE Name = N'columnName'
          AND Object_ID = Object_ID(N'schemaName.tableName'))
BEGIN
    -- Column Exists
END

Martin Smith's version is shorter:

IF COL_LENGTH('schemaName.tableName', 'columnName') IS NOT NULL
BEGIN
    -- Column Exists
END

Best Answer

Related Solutions

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

Syntax:

Example:

Notes:

Sql-server – How to check if a column exists in a SQL Server table

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