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.
Primary key not null in SQL Server. A Jr. Developer asked me why a primary key not null in SQL Server. A primary key uniquely identifies a row in a table and a NULL canât identify any row. Moreover, a primary key is used to find rows in a table and is essential for indexing and maintaining data. Letâs see what happens if we try to add a primary key constraint on a null able column. As shown in above image, the SQL Server terminates with error when creating primary key on a null able column. Letâs see the behavior when defining composite primary key. The SQL Server again terminates with error.