COMPUTER SCIENCE AND ENGINEERING
SQL
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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hat is the one thing we need to pay attention to when we need to use constraints?
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Can be used with both Insert and Delete.
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Can be used with only Insert.
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Can only be used with the Create clause.
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Can be used with Create, Insert and Delete.
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Explanation:
Detailed explanation-1: -You use the CONSTRAINT clause in ALTER TABLE and CREATE TABLE statements to create or delete constraints. There are two types of CONSTRAINT clauses: one for creating a constraint on a single field and one for creating a constraint on more than one field.
Detailed explanation-2: -The NOT NULL constraint can be created at either the column level or the table level.
Detailed explanation-3: -Explanation: Constraints are Primary key, Foreign Key, Unique Key, Not Null, Check, Default.
Detailed explanation-4: -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.
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