SQL - Lecture 3 - Default Expression & Check Constraints - Oracle - Practical Demonstrations

This video demonstrates step by step implementation of default expression and check constraints in details.

Lecture Summary

*DEFAULT* is used to insert the default value.

If default is set into column then we can insert it in 2 ways.
1. Using Default keyword
2. By skipping the column at time of insert.

*Check constraint*
It is used to put validation on column for each row.

Syntax:
CHECK (condition)

Example
*1.* CHECK(CITY = 'RAJKOT')
*2.* CHECK(LENGTH(MOBILE)=10)
*3.* CHECK(EMAILID LIKE '___%@__%.__%')
*4.* CHECK(SUBSTR(NAME,1,1) BETWEEN 'A' AND 'P')
*5* CHECK (CITY IN ('AHM', 'RJT', 'SURAT'))

*Note*
CONSTRAINT constraint_name is recommended for each constraints to identify constraints at the time of violations.

Constraint name is unique within the database.

*Syntax of table*
CREATE TABLE table_name(
col1 data_type [default expr] [ [constraint constraint_name] constraint_type ],

col2 data_type [default expr] [ [constraint constraint_name] constraint_type ],
.
.
colN data_type [default expr] [ [constraint constraint_name] constraint_type ], [table_level_constraint]
)

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[ousmanekaba]

thank you so much sir .i wish your classes will be liked by many students who really want to know oracle like me .since i started taking your classes i haven't met any problem .you are genus .keep up being there for people in need

[sanamoughal]

Thanks a lot sir. Feels as if I am doing hands-on.

[khalidalmohammadi]

Thank you so much, I’ve learned a lot
Could you please tell me how I add check constraint for date (end_date> start_date) ?