what is Constraint? How many types of constraints in SQL ?
Answers were Sorted based on User's Feedback
Answer / pramod tiwari,mba-it,lpu
SQL Constraints-
Constraints are used to limit the type of data that can go
into a table.
Constraints can be specified when a table is created (with
the CREATE TABLE statement) or after the table is created
(with the ALTER TABLE statement).
We will focus on the following constraints:
•NOT NULL
•UNIQUE
•PRIMARY KEY
•FOREIGN KEY
•CHECK
•DEFAULT
Is This Answer Correct ? | 9 Yes | 1 No |
Answer / nambi rajan
A constraint is a property assigned to a column or the set
of columns in a table that prevents certain types of
inconsistent data values from being placed in the columns.
There are 4 Types of Constraints.
• Entity Integrity - Primary and Unique
• Domain Integrity - Default, Check and Not Null
• Referential integrity – Foreign Key
• User-Defined Integrity - enforces some specific
business rules that do not fall into entity, domain, or
referential integrity categories
Is This Answer Correct ? | 13 Yes | 7 No |
Answer / rohit nanda
A constraint is a property assigned to a column or the set
of columns in a table that prevents certain types of
inconsistent data values from being placed in the columns.
There are 4 Types of Constraints.
• Entity Integrity - Primary and Unique
• Domain Integrity - Default, Check and Not Null
• Referential integrity – Foreign Key
• User-Defined Integrity - enforces some specific
Is This Answer Correct ? | 7 Yes | 3 No |
Answer / ramesh.n
constraints are the restrictions or limitations that are
being imposed on the columns of a table to validate the data
either for insertion or updation constraints can be imposed
either during the process of table creation of a level.
There are 8 types of constraints
1.unique
2.Not null
3.Primary key
4.Check
5.Default
6.Foreign key
7.composite primary key
8.composite unique key
Is This Answer Correct ? | 6 Yes | 2 No |
Answer / seshu
constraint is a mechanism it is used to prevent the invalid
data entry in to the table is called constraint.
constraints are 5 types they are,
1 Primary Key Constraint
2 Foreign Key Constraint
3 Unique Constraint
4 Not Null Constraint
5 Check Constraint
Is This Answer Correct ? | 5 Yes | 1 No |
Answer / sivanagireddy.k
constraints nothing but condition on column in the table by using constraint checking process or validation pprocess has been done.
constraints are 6 tyes
1.unique
2.Not null
3.Primary key
4.Check
5.Default
6.Foreign key
types of level in constraints
column level
table level
send ur queries to this mail id rsivanagireddy@gmail.com
Is This Answer Correct ? | 4 Yes | 0 No |
Answer / shelly
Constraints are used to limit the type of data that goes
into a table.Constraints can be declared at the time of
creating a table or by altering the already created table.
1)Not Null
2)Unique
3)Primary Key
4)Check
5)References
6)Default
Is This Answer Correct ? | 2 Yes | 0 No |
Answer / manoj kumar
Contraint is a provision to limit or enforce the data in
the sql tables. It is of five types:-
1 Primary Key Constraint
2 Foreign Key Constraint
3 Unique Constraint
4 Not Null Constraint
5 Check Constraint
Is This Answer Correct ? | 7 Yes | 6 No |
Answer / krishna
constraints are use to maintain the relation between the two tables. sql contains the 5 types of constraints
1.primary key
2.foreign key
3.unique key
4.Not null
5.check
Is This Answer Correct ? | 2 Yes | 1 No |
Answer / m arunachalam
Constraints are used to limit the type of data that can go
into a table.
Constraints can be specified when a table is created (with
the CREATE TABLE statement) or after the table is created
(with the ALTER TABLE statement).
We will focus on the following constraints:
NOT NULL
UNIQUE
PRIMARY KEY
FOREIGN KEY
CHECK
DEFAULT
Is This Answer Correct ? | 1 Yes | 0 No |
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