markzzz markzzz - 1 year ago 80
MySQL Question

Java & MySql - How to escape query before execute it

I'm using Java for a web application, and I'm working with a MySql database. I need to escape the query before execute it. This is my actual code :

db_result=mydb.selectQuery("SELECT nickname FROM users WHERE nickname='"+log_check_user+"' AND password='"+log_check_pass+"'");

public Vector selectQuery(String query) {
Vector v = null;
String [] record;
int colonne = 0;
try {
Statement stmt = db.createStatement();
ResultSet rs = stmt.executeQuery(query);
v = new Vector();
ResultSetMetaData rsmd = rs.getMetaData();
colonne = rsmd.getColumnCount();

while( {
record = new String[colonne];
for (int i=0; i<colonne; i++) record[i] = rs.getString(i+1);
v.add( (String[]) record.clone() );
} catch (Exception e) { e.printStackTrace(); errore = e.getMessage(); }

return v;

I need this, as you can believe, to avoid the SQL Injection problem! How can I do it?

Answer Source

Use a prepared statement:

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...

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. The advantage to this is that in most cases, this SQL statement is sent to the DBMS right away, where it is compiled. As a result, the PreparedStatement object contains not just a SQL statement, but a SQL statement that has been precompiled. This means that when the PreparedStatement is executed, the DBMS can just run the PreparedStatement SQL statement without having to compile it first...

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