PREPARED STATEMENT

• It is an interface.
• It is a sub-type of Statement.
• It is implemented by JDBC driver developers.
• An object that represents a pre-compiled SQL statements.
• A SQL statement is pre-compiled and stored in a PreparedStatement object. This object can then be used to efficiently execute this statement multiple times.
• PreparedStatement allows SQL statement with parameters.

How to create PreparedStatement object

Connection provide the following method which return PreparedStatement object.

• PreparedStatement prepareStatement(String sql) - creates a PreparedStatement object for sending parameterized SQL statements to the database.
• Example - PreparedStatement ps = con.prepareStatement(select * from emp);

What is the difference between Statement and PreparedStatement

1. A standard Statement is used to create java representation of a literal SQL statement and execute it on the database, A PreparedStatement is a pre-compiled Statement. This means that when the PreparedStatement is executed, the RDBMS can just run the PreparedStatement SQL statement without having to compile it first.
2. Statement has to verify its metadata against the database every-time, While a PreparedStatement has to verify its metadata against the database only once.
3. If we want to execute the SQL statement once then we should go for Statement, If we want to execute a single SQL statement multiple number of times, then we should go for PreparedStatement. PreparedStatement objects can be reused with passing different values to the queries.

How to define Parameters

• Parameter is a place-holder which receive value after compiling SQL statement.
• Each parameter is represented using a special symbol  " ? ".
• It is identified with index number.
• This index number starts with 1.
• PreparedStatement provides setter methods to define the value of each parameter.
• For each datatype it provide one setter method.

PreparedStatement provides the following methods -

• void setInt(int paramIndex, int value);
• void setFloat(int paramIndex, float value);
• void setDouble(int paramIndex, double value);
• void setString(int paramIndex, String value);