Java - Getting Data from MySQL database
Here you go :
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con = DriverManager.getConnection("jdbc:mysql://localhost/t", "", "");
Statement st = con.createStatement();
String sql = ("SELECT * FROM posts ORDER BY id DESC LIMIT 1;");
ResultSet rs = st.executeQuery(sql);
if(rs.next()) {
int id = rs.getInt("first_column_name");
String str1 = rs.getString("second_column_name");
}
con.close();
In rs.getInt
or rs.getString
you can pass column_id
starting from 1
, but i prefer to pass column_name
as its more informative as you don't have to look at database table
for which index
is what column
.
UPDATE : rs.next
boolean next() throws SQLException
Moves the cursor froward one row from its current position. A ResultSet cursor is initially positioned before the first row; the first call to the method next makes the first row the current row; the second call makes the second row the current row, and so on.
When a call to the next method returns false, the cursor is positioned after the last row. Any invocation of a ResultSet method which requires a current row will result in a SQLException being thrown. If the result set type is TYPE_FORWARD_ONLY, it is vendor specified whether their JDBC driver implementation will return false or throw an SQLException on a subsequent call to next.
If an input stream is open for the current row, a call to the method next will implicitly close it. A ResultSet object's warning chain is cleared when a new row is read.
Returns: true if the new current row is valid; false if there are no more rows Throws: SQLException - if a database access error occurs or this method is called on a closed result set
reference
Something like this would do:
public static void main(String[] args) {
Connection con = null;
Statement st = null;
ResultSet rs = null;
String url = "jdbc:mysql://localhost/t";
String user = "";
String password = "";
try {
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection(url, user, password);
st = con.createStatement();
rs = st.executeQuery("SELECT * FROM posts ORDER BY id DESC LIMIT 1;");
if (rs.next()) {//get first result
System.out.println(rs.getString(1));//coloumn 1
}
} catch (SQLException ex) {
Logger lgr = Logger.getLogger(Version.class.getName());
lgr.log(Level.SEVERE, ex.getMessage(), ex);
} finally {
try {
if (rs != null) {
rs.close();
}
if (st != null) {
st.close();
}
if (con != null) {
con.close();
}
} catch (SQLException ex) {
Logger lgr = Logger.getLogger(Version.class.getName());
lgr.log(Level.WARNING, ex.getMessage(), ex);
}
}
}
you can iterate over the results with a while
like this:
while(rs.next())
{
System.out.println(rs.getString("Colomn_Name"));//or getString(1) for coloumn 1 etc
}
There are many other great tutorial out there like these to list a few:
- http://www.vogella.com/articles/MySQLJava/article.html
- http://www.java-samples.com/showtutorial.php?tutorialid=9
As for your use of Class.forName("com.mysql.jdbc.Driver").newInstance();
see JDBC connection- Class.forName vs Class.forName().newInstance? which shows how you can just use Class.forName("com.mysql.jdbc.Driver")
as its not necessary to initiate it yourself
References:
- http://zetcode.com/databases/mysqljavatutorial/