In Emp table, columns are Empno(PK) ,EmpName and Deptno(foreign key referring to Dept)To Insert or Update record in Emp through application, value of Deptno is coming as 0(Zero). The table in the destination has a column which allow null values and has also a default constraint (getdate()), and this column is not present in the source
Uh! I almost felt like going back in time some ten years when I was writing kernel drivers for Windows :) This is excellent participation from experts like Marko and Brian. Is it better write a function Drop table and and pass table name as parameter to do this? In my opinion, I think it is expensive to go to a function from a stored procedure just to drop a table
ALTER TABLE only allows columns to be added that can contain nulls, or have a DEFAULT definition specified, or the column being added is an identity or timestamp column, or alternatively if none of the previous conditions are satisfied the table must be empty to allow addition of this column. Fill in your details below or click an icon to log in: Email (required) (Address never made public) Name (required) Website You are commenting using your WordPress.com account
This -- Trying to add a NOT NULL column without a default ALTER TABLE DefaultTest ADD NotNull2 char(1) NOT NULL GO Returns an error of Msg 4901, Level 16, State 1, Line 1 ALTER TABLE only allows columns to be added that can contain nulls, or have a DEFAULT definition specified, or the column being added is an identity or timestamp column, or alternatively if none of the previous conditions are satisfied the table must be empty to allow addition of this column. Fill in your details below or click an icon to log in: Email (required) (Address never made public) Name (required) Website You are commenting using your WordPress.com account
The post prompted me to revisit the Books On Line page for the ALTER TABLE statement and with subsequent research, I realized that SQL Server actually empowers us with different methods to work with default values depending upon whether we are adding a new column to an existing table or when we are altering an existing column. Adding a new column to an existing table If the column is being added to an existing table and has a default definition available, then the ALTER TABLE statement allows us to use the WITH VALUES clause to store the default value in each existing record of the table
sql server 2008 - Quickly change NULL column to NOT NULL - Database Administrators Stack Exchange
One problem with this is that even if you know the column in fact has no NULLs the constraint is not trusted by the query optimiser which means that the plans can be sub optimal. Adding the constraint with NOCHECK means that no rows will need to be read to verify it, and if you are starting from a position where the column does not contain NULL values (and if you know none will be added between checking and adding the constraint) then, as the constraint prevents NULL values being created from future INSERT or UPDATE operations, this will work
Instead, Enterprise Manager creates a new table that has the new schema with the changed nullability setting, uses an INSERT INTO statement to move the data into the new table, then deletes the old table. If you use SQL Server Profiler to trace the activity of Enterprise Manager, you'll see that Enterprise Manager can issue more than 150 commands that change the nullability of a column
sql server - Why does ALTER COLUMN to NOT NULL cause massive log file growth? - Database Administrators Stack Exchange
But it's clear that - while both the update operation and the addition of the NOT NULL constraint undeniably write to the page - the latter does so in an entirely different way. On databases with one of the snapshot isolation options enabled then the versioning information in each row is updated (@SQL Kiwi points out that this can also occur in databases without SI enabled as described here)
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