Why prepared statement is called precompiled

The reason being it is compiled. When you use prepared statement i. So it becomes pre-compiled for successive calls. You generally use prepared statement with bind variables where you provide the variables at run time. Now what happens for successive execution of prepared statements, you can provide the variables which are different from previous calls.

From DB point of view, it does not have to compile the statement every time, will just insert the bind variables at rum time. So becomes faster. Precompilation is done by the database.

Some simpler databases don't precompile statements at all. Others might precompile it on the prepareStatement call, and yet others might do it when execute is first called on the statement, taking values of the parameters into account when compiling creating a plan for the statement. Databases that do precompile statements usually cache them, so in all probability ps1 won't be compiled again.

Some JDBC drivers eg. If you want to execute a Statement object many times, it usually reduces execution time to use a PreparedStatement object instead.

The main feature of a PreparedStatement object is that, unlike a Statement object, it is given a SQL statement when it is created. Although you can use PreparedStatement objects for SQL statements with no parameters, you probably use them most often for SQL statements that take parameters. The advantage of using SQL statements that take parameters is that you can use the same statement and supply it with different values each time you execute it. Examples of this are in the following sections.

However, the most important advantage of prepared statements is that they help prevent SQL injection attacks. SQL injection is a technique to maliciously exploit applications that use client-supplied data in SQL statements. Attackers trick the SQL engine into executing unintended commands by supplying specially crafted string input, thereby gaining unauthorized access to a database to view or manipulate restricted data.

SQL injection techniques all exploit a single vulnerability in the application: Incorrectly validated or nonvalidated string literals are concatenated into a dynamically built SQL statement and interpreted as code by the SQL engine. Prepared statements always treat client-supplied data as content of a parameter and never as a part of an SQL statement. Collectives on Stack Overflow. Learn more. What does it mean when I say Prepared statement is pre-compiled? Ask Question.

Asked 7 years, 5 months ago. Active 4 years, 3 months ago. Viewed 11k times. What do we mean by compiled? Improve this question. Lukas Kabrt 5, 4 4 gold badges 41 41 silver badges 58 58 bronze badges.

Add a comment. Active Oldest Votes. Other advantages of prepared statements are :- 1 protection against SQL-injection attack 2 Faster for successive calls of same statements How it works :- Precompilation is done by the database. Databases generally cache statements until something evicts them from the cache. Improve this answer. Buhake Sindi 84k 27 27 gold badges silver badges bronze badges. M Sach M Sach In the MySQL documentation, the compilation phase is mostly described as the optimization phase.

I don't have a good understanding of PreparedStatement. I know it is better to use PreparedStatement than Statement. The reason being it is compiled. When you use prepared statement i. So it becomes pre-compiled for successive calls. You generally use prepared statement with bind variables where you provide the variables at run time.

Now what happens for successive execution of prepared statements, you can provide the variables which are different from previous calls. From DB point of view, it does not have to compile the statement every time, will just insert the bind variables at rum time. So becomes faster.