Constraints can be enforced at two levels:
* Column level
* Table level
A constraint can be created with either of the following statements:
* CREATE TABLE
* ALTER TABLE
With the ALTER TABLE statement, you can disable or enable the imposed constraint without dropping it or re-creating it:
* Disable a constraint by using the DISABLE clause.
* Enable a constraint by using the ENABLE clause.
Creating Constraints
Sunday, January 31, 2010
by
Abdul Majid Niazi
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2010
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January
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- Creating Groups: Part 1
- Using the Grouping Functions
- Group Functions: Part 2
- Group Functions: Part 1
- Group Functions: Part 1
- Working with Groups of Data
- Using the NVL Function
- Using the NVL Function
- Formatting Dates
- Formatting Dates
- Using Date Functions
- Date Functions: Part 2
- Date Functions: Part 1
- Using Numeric Functions
- Number Functions
- Using Character Functions
- Character Functions: Part 2
- Character Functions: Part 1
- Using Functions to Customize Reports
- Joining Multiple Tables
- Joining Multiple Tables
- Applying Additional Conditions to a Join
- Applying Additional Conditions to a Join
- Joining Tables and Identifying Columns
- Joining Tables and Identifying Columns
- Simple Joins
- Simple Joins
- Joining Tables
- Retrieving Rows
- Retrieving Rows
- Retrieving Columns
- Retrieving Columns
- Writing a Basic Query
- Writing a Basic Query
- Building Queries
- Building Queries: Part 2
- Building Queries
- Accessing Data
- Removing a Copy of a Table
- Removing Tables
- Implementing Business Rules
- Creating Constraints
- Identifying Constraints
- Managing Constraints
- Adding a New Column
- Modifying Tables
- Creating a Copy of a Table
- Creating Tables Using SQL
- Creating Tables by Using the Object Browser
- Creating Tables
- Working with Database Objects
- Relational data base
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