Mikhail Gorbachev's policies of glasnost and perestroika had profound and unintended effects on the Soviet Union. In fact, many historians suggest these reforms led directly to the fall of communism and the breakup of the Soviet Union.
In SQL Server, you create a surrogate key by assigning an identity property to a column that has a number data type. A natural key is a naturally occurring descriptor of the data and one of a table's attributes that has no duplicate values. When you use a natural key as a table's primary key, each of the table's rows is uniquely identified.
and. unfortunately SQL does not permit a select count(distinct). You have duplicate records if the number of records returned by the second query is less than the number of records returned by the first. Unfortunately there is no way in SQL to delete one of these duplicates without deleting all of them.They are identical after all, so there is no SQL query that you could put together which could distinguish between them. What you can do is to copy all the distinct records into a new table:nfortunately there is no way in SQL to delete one of these duplicates without deleting all of them. They are identical after all, so there is no SQL query that you could put together which could distinguish between them.