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7 Advanced JDBC Connector Functionality : 7.2 Using PreparedStatements to Send SQL Commands

Many applications execute the same SQL statement over and over again, changing one or more of the data values in the statement between each iteration. If you use a Statement object to repeatedly execute a SQL statement, the server must parse, plan, and optimize the statement every time. JDBC offers another Statement derivative, the PreparedStatement to reduce the amount of work required in such a scenario.
Listing 1.6 demonstrates invoking a PreparedStatement that accepts an employee ID and employee name and inserts that employee information in the emp table:
Instead of hard-coding data values in the SQL statement, you insert placeholders to represent the values that will change with each iteration. Listing 1.6 shows an INSERT statement that includes two placeholders (each represented by a question mark):
With the parameterized SQL statement in hand, the AddEmployee() method can ask the Connection object to prepare that statement and return a PreparedStatement object:
At this point, the PreparedStatement has parsed and planned the INSERT statement, but it does not know what values to add to the table. Before executing the PreparedStatement, you must supply a value for each placeholder by calling a setter method. setObject() expects two arguments:
The AddEmployee() method prompts the user for an employee ID and name and calls setObject() with the values supplied by the user:
And then asks the PreparedStatement object to execute the statement:
If the SQL statement executes as expected, AddEmployee() displays a message that confirms the execution. If the server encounters an exception, the error handling code displays an error message.

7 Advanced JDBC Connector Functionality : 7.2 Using PreparedStatements to Send SQL Commands

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