frankies/0_call_custom_function.md

## 0_call_custom_function.md

      
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              0_call_custom_function.md
            
          
自定义一个函数calculate
创建脚本,

CREATE OR REPLACE FUNCTION calculate(IN x double precision, IN y double precision, OUT sum double precision) RETURNS double precision AS $BODY$ BEGIN sum = x + y; END; $BODY$ LANGUAGE plpgsql VOLATILE COST 100; 


在JPA 中调用

		TypedQuery<Book> q = em.createQuery(
			    "SELECT b "
			    + "FROM Book b "
			    + "WHERE :double2 > function('calculate', b.price, :double1)"
			    , Book.class);
Important


** WHERE :double2 > function('calculate', b.price, :double1)" **