CallableStatement interface is used to call the stored procedures and functions.
We can have business logic on the database by the use of stored procedures and functions that will make the performance better because these are precompiled.
Suppose you need the get the age of the employee based on the date of birth, you may create a function that receives date as the input and returns age of the employee as the output.
The differences between stored procedures and functions are given below:
is used to perform business logic.
must not have the return type.
may return 0 or more values.
We can call functions from the procedure.
Procedure supports input and output parameters.
Exception handling using try/catch block can be used in stored procedures.
is used to perform calculation.
must have the return type.
may return only one values.
Procedure cannot be called from function.
Function supports only input parameter.
Exception handling using try/catch can't be used in user defined functions.
The prepareCall() method of Connection interface returns the instance of CallableStatement. Syntax is given below:
To call the stored procedure, you need to create it in the database. Here, we are assuming that stored procedure looks like this.
In this example, we are calling the sum4 function that receives two input and returns the sum of the given number. Here, we have used the registerOutParameter method of CallableStatement interface, that registers the output parameter with its corresponding type. It provides information to the CallableStatement about the type of result being displayed. The Types class defines many constants such as INTEGER, VARCHAR, FLOAT, DOUBLE, BLOB, CLOB etc. Let's create the simple function in the database first.
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