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Tommy
Tommy

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Hibernate - @Formula

Formula Annotation

The @Formula annotation is used to calculate the dynamic value of a property. @Formula takes an expression (this could be simple expression or a complex query) as a parameter. During fetch time, it evaluates the expression and assigns the evaluated value to the property.

Examples

// ex 1
@Formula("lower(datediff(curdate(), birth_date / 365)")
private int age;

// ex 2
@Formula("(select min(s.survey) from statistics s) ")
private float total;

// ex 3
private int num1;
private int num2;
private int num3;

@Formula(" num1 + num2 + num3")
private float totalSum;

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Note:
-This is only inserted in a SELECT clause!
-Be careful when using this because the SQL command you may be using may be vendor specific. In other words, this will create coupling with a particular SQL vendor.

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