What are various constraints used in SQL?
SQL constraints are used to specify rules for the data in a table.
NOT NULL - Indicates that a column cannot store NULL value
UNIQUE - Ensures that each row for a column must have a unique value
PRIMARY KEY - A combination of a NOT NULL and UNIQUE. Ensures that a column (or combination of two or more columns) have an unique identity which helps to find a particular record in a table more easily and quickly
FOREIGN KEY - Ensure the referential integrity of the data in one table to match values in another table
CHECK - Ensures that the value in a column meets a specific condition
DEFAULT - Specifies a default value when specified none for this column
Is This Answer Correct ? | 1 Yes | 0 No |
What is tns service name?
How to convert character types to numeric types?
Can we convert a date to char in oracle and if so, what would be the syntax?
how the Oracle Prepares the Execution Plan and how it chooses the Optimal one?
waht is the difference between primary key and super key?
What would you do with an in-doubt distributed transaction?
How much memory your 10g xe server is using?
How can we find out the current date and time in oracle?
Explain the use of show option in imp command.
What is format trigger?
what are the database links ?
What is SAVE POINT ?