A prepared statement is a feature used to execute the same (or similar) SQL statements repeatedly with high efficiency. 
The Prepared property can be used when executing a statement with multiple parameter sets. An application can execute a parameterized statement more than once by supplying a different parameter set at each execution instead of reconstructing the statement whenever the parameter set is different. The SQL Server relational engine introduces full support for preparing SQL statements before they are executed. If an application has to execute an SQL statement several times, it can use the database API to do the following: Prepare the statement once. This compiles the SQL statement into an execution plan. Overview of Prepared Statements. Sometimes it is more convenient to use a PreparedStatement object for sending SQL statements to the database. This special type of statement is derived from the more general class, Statement, that you already know. SQL syntax for prepared statements is distinct from using prepared statement API calls. For example, you cannot use the mysql_stmt_prepare() C API function to prepare a PREPARE, EXECUTE, or DEALLOCATE PREPARE statement. The MySQL database supports prepared statements. A prepared statement or a parameterized statement is used to execute the same statement repeatedly with high efficiency. Basic workflow. The prepared statement execution consists of two stages: prepare and execute. At the prepare stage a statement template is sent to the database server. The server performs a syntax check and initializes server internal resources for later use. Prepared Statements and Bound Parameters. A prepared statement is a feature used to execute the same (or similar) SQL statements repeatedly with high efficiency. Prepared statements basically work like this: 1  Prepare: An SQL statement template is created and sent to the database.
https://technet.microsoft.com/en-us/library/aa905910(v=sql.80).aspx https://technet.microsoft.com/en-us/library/ms175528(v=sql.105).aspx http://docs.oracle.com/javase/tutorial/jdbc/basics/prepared.html http://dev.mysql.com/doc/refman/5.6/en/sql-syntax-prepared-statements.html http://php.net/manual/en/mysqli.quickstart.prepared-statements.php http://www.w3schools.com/php/php_mysql_prepared_statements.asp
what is a prepared statement