Interested to Buy Any Domain ? << Click Here >> for more details...
What are various constraints used in SQL?
- 1 Answers
- 3835 Views
- Polaris, I also Faced
- E-Mail Answers
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 ? | 2 Yes | 0 No |
What is Read-Only Transaction ?
How would you best determine why your MVIEW couldnt FAST REFRESH?
What is a initialization parameter file in oracle?
what is the syntax of UPDATE command?
What spfile/init.ora file parameter exists to force the CBO to make the execution path of a given statement use an index, even if the index scan may appear to be calculated as more costly?
how many outer joins are used in a single sql query? is there any limitations for using of outer joins?
2 Answers BOB Technologies, Cap Gemini, IBM,
Explain the use of show option in imp command.
Can a Tablespace hold objects from different Schemes ?
how to get last monday of a month?
What is a Segment ?
What is the effect of setting the value "ALL_ROWS" for OPTIMIZER_GOAL parameter of the ALTER SESSION command ?
How to use an explicit cursor without open statements?
Oracle General 
