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;
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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