Which of the following is NOT a type of SQL constraint?
A. PRIMARY KEY
B. ALTERNATE KEY
C. FOREIGN KEY
D. UNIQUE
Answer: Option B
Solution(By Examveda Team)
An ALTERNATE KEY is not a type of SQL constraint. The other options, PRIMARY KEY, FOREIGN KEY, and UNIQUE, are all types of constraints used in SQL:PRIMARY KEY ensures that a column or set of columns uniquely identifies each row in a table.
FOREIGN KEY establishes a link between two tables, enforcing referential integrity between them.
UNIQUE constraint ensures that values in a column (or set of columns) are unique across the table, but it doesn't require that the column(s) be the primary means of identifying rows.
Option B, ALTERNATE KEY, is not a standard SQL constraint term.
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There is no such term "ALTERNATE KEY" exists in SQL