Oracle SQL in 10 Minutes - Asim Abbasi
CH1: SQL Basics | CH2: SQL Operators | CH3: SQL Built-in Functions | CH4: SQL Joins | CH5: UPDATE, INSERT & DELETE Statements | CH6: CREATE, ALTER & DROP Statements | CH7: Constraints | CH8: Linking Tables vs Joining Tables | CH9: SQL Statements for Other Database Objects | CH10: SQL Statements for Database Security
Chapter 7: Constraints
Constraints:
While creating tables we can assign constraints on each column wherever
we feel necessary. Constraints help in achieving data integrity. In
other words, before inserting or updating any information in database
Oracle instance makes sure that none of the constraints get violated.
For example if you have implemented UNIQUE constraint on one column and
if you try to insert a record with a duplicate value that was already
there in the column having UNIQUE constraint, you will get a “constraint
violation” error. Let’s study all of these constraints and their
applications one by one.
Figure 15: Data integrity constraints or simply
constraints.
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Chapter 7: Constraints
CH1: SQL Basics | CH2:
SQL Operators |
CH3: SQL Built-in Functions | CH4:
SQL Joins | CH5:
UPDATE, INSERT & DELETE Statements |
CH6: CREATE, ALTER & DROP Statements | CH7:
Constraints | CH8:
Linking Tables vs Joining Tables | CH9:
SQL
Statements for Other Database Objects | CH10:
SQL Statements for
Database Security Share with others: