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Constraints

NOT NULL CONSTRAINT -    Ensures that a column cannot have a null value. DEFAULT CONSTRAINT -    Provides a default value for a column when none is specified  UNIQUE CONSTRAINT -   Ensures that all values in columns are different  CHECK CONSTRAINT -   Makes sure that all values in a column satisfy certain criteria  PRIMARY KEY CONSTRAINT -   Used to uniquely identify a row in the table  FOREIGN KEY CONSTRAINT -   Used to ensure referential integrity of the data  Primary Key - is used uniquely to identify each row in a table . It can consist of one or more columns on a table . When Multiple columns are used on a table it is called composite key.  Foreign Key - Foreign key is a column or columns that references a column most often primary key of another table . The purpose of foreign key is to maintain referential integrity of the data. Pg admin  Data base - training - right click on training - query click  Always add semi colen to run the query  Int - integer  varchar - variable charact
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Difference between Investor and Speculation

 Investor is one who purchase of an asset with the expansion of getting returns is called investment .

Speculation is a risky transaction with an expectation of substantial profit. 

Investment is a longer planning horizon

Speculation is shorter planning horizon

Investor not take more than moderate risk 

Speculation expects higher return in exchange for the high risk 

Investor analysis based on the fundamental factors.

Speculator relies more than on the technical charts , market psychology .

Investor psychology attitude of investor are risk averse 

The psychological attitude of speculators are risk taker

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