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Delete column from table

When we delete a column from a table, it and all the data it contains are deleted from the database. This action cannot be undone.
We cannot delete a column that has a CHECK constraint. You must first delete the constraint.we cannot delete a column that has PRIMARY KEY or FOREIGN KEY constraints or other dependencies except when using the Table Designer. When using Object Explorer or Transact-SQL, we must first remove all dependencies on the column.
ALTER TABLE dbo.TableName DROP COLUMN column_b ;


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