BUSINESS ADMINISTRATION
BUSINESS ANALYTICS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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NOT NULL
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Primary key
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Check
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unique
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Detailed explanation-1: -A foreign key (FK) is a column or combination of columns that is used to establish and enforce a link between the data in two tables to control the data that can be stored in the foreign key table.
Detailed explanation-2: -The CHECK constraint is used to limit the value range that can be placed in a column. If you define a CHECK constraint on a column it will allow only certain values for this column.
Detailed explanation-3: -A NOT NULL constraint is a rule that prevents null values from being entered into one or more columns within a table. A unique constraint (also referred to as a unique key constraint) is a rule that forbids duplicate values in one or more columns within a table.
Detailed explanation-4: -A foreign key is a column (or combination of columns) in a table whose values must match values of a column in some other table. FOREIGN KEY constraints enforce referential integrity, which essentially says that if column value A refers to column value B, then column value B must exist.