I have a database table with columns : name, residence, contact. and I want to retrieve only the values in the 'contact column' into an array. the following code is what I wrote:
List l = new ArrayList();
try {
String sql = "select * from members";
pst = conn.prepareStatement(sql);
rs = pst.executeQuery();
while (rs.next()) {
String con = rs.getString("Contact");
l.add(con);
System.out.println(l);
}
} catch (Exception e) {
e.getMessage();
}
but this generates the following result:
[0547615632]
[0547615632, 0246687643]
[0547615632, 0246687643, 0558581764]
whilst I have only 3 records in the table and each having a contact value.
please how do I write the code so that I can get only a single array displaying the result like this:
[0547615632, 0246687643, 0558581764]
thank you very much.
You should move the print command out of the while loop:
List l = new ArrayList();
try {
String sql = "select * from members";
pst = conn.prepareStatement(sql);
rs = pst.executeQuery();
while (rs.next()) {
String con = rs.getString("Contact");
l.add(con);
}
} catch (Exception e) {
e.getMessage();
}
System.out.println(l);
OR only print the current element in each iteration;
List l = new ArrayList();
try {
String sql = "select * from members";
pst = conn.prepareStatement(sql);
rs = pst.executeQuery();
while (rs.next()) {
String con = rs.getString("Contact");
l.add(con);
System.out.print(con + " ");
}
} catch (Exception e) {
e.getMessage();
}
I have following code,
private void trans_tabMouseClicked(java.awt.event.MouseEvent evt) {
try{
con = DriverManager.getConnection("jdbc:mysql://localhost:3306/online_store","poornima","mit1234");
if(con != null){
String query = "SELECT * FROM bill";
rs = stmt.executeQuery(query);
System.out.println("fffgg");
ResultSetMetaData rsmt = rs.getMetaData();
int c = rsmt.getColumnCount();
Vector row = new Vector();
DefaultTableModel model = (DefaultTableModel)expense_table.getModel();
while(rs.next())
{
row = new Vector(c);
for(int i = 1; i <= c; i++)
{
row.add(rs.getString(i));
}
model.addRow( row );
}
}
}catch(Exception ex){
System.out.println(ex);
}
}
in the above code query is not executed. Fired null pointer exception at rs = stmt.executeQuery(query); line. I tried hours, but I can't figure out where the issue is. Please help.
because stmt is null.
use this
String query = "SELECT * FROM bill";
stmt = con.createStatement();
rs = stmt.executeQuery(query);
instead of this
String query = "SELECT * FROM bill";
rs = stmt.executeQuery(query);
refer this
Hello I would like to print data from mysql query to my Jtable, I knw how to print the conventional data(String), but do not know how to do it with pictures. What I need is print the picture in the first cell of the table.
public void SearchMovie() throws SQLException {
try {
Connection con = null;
ResultSet rs = null;
Statement st = null;
String Genre = ComboGenero.getSelectedItem().toString();
String Era = ComboEra.getSelectedItem().toString();
String Clsssification = ComboClasification.getSelectedItem().toString();
String sql = "select Foto,Title,Year,Country ,Rating from movie where Genre ='" + Genre + "'";
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection("jdbc:mysql://localhost/whichmovie", "Asis", "dekrayat24");
st = con.createStatement();
rs = st.executeQuery(sql);
DefaultTableModel model = new DefaultTableModel();
this.jTable1.setModel(model);
jTable1.setDefaultRenderer(Object.class,new IconCellRenderer());
jTable1.setRowHeight(40);
ResultSetMetaData rsMD = rs.getMetaData();
int numcolumnas = rsMD.getColumnCount();
for (int x = 1; x <= numcolumnas; x++) {
model.addColumn(rsMD.getColumnLabel(x));
}
while (rs.next()) {
Object[] fila = new Object[numcolumnas];
for (int i = 0; i < numcolumnas; i++) {
fila[i] = rs.getObject(i + 1);
ResultadosLabel.setText(numcolumnas + "Movies found");
}
model.addRow(fila);
}
rs.close();
st.close();
con.close();
} catch (ClassNotFoundException ex) {
System.out.println(ex.getMessage());
}
}
Thanks .
I have tried different ways to get the row count in java JDBC, nut none seemed to be giving the correct result. Is there anything wrong that I am doing ?
Even though the customer table is empty and I should be getting the rowcount as 0, I don't understand why I get a non zero rowcount value.
Method 1 -
query = "SELECT * FROM customer WHERE username ='"+username+"'";
rs = stmt.executeQuery(query);
ResultSetMetaData metaData = rs.getMetaData();
rowcount = metaData.getColumnCount();
Method 2 -
query = "SELECT * FROM customer WHERE username ='"+username+"'";
rs = stmt.executeQuery(query);
rowcount = rs.last() ? rs.getRow() : 0;
See this snippet of code:
import java.io.*;
import java.sql.*;
public class CountRows{
public static void main(String[] args) {
System.out.println("Count number of rows in a specific table!");
Connection con = null;
int count = 0;
try {
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbctutorial","root","root");
try {
Statement st = con.createStatement();
BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter table name:");
String table = bf.readLine();
ResultSet res = st.executeQuery("SELECT COUNT(*) FROM "+table);
while (res.next()){
count = res.getInt(1);
}
System.out.println("Number of row:"+count);
}
catch (SQLException s){
System.out.println("SQL statement is not executed!");
}
}
catch (Exception e){
e.printStackTrace();
}
}
}
This the way I use to get the row count in Java:
String query = "SELECT * FROM yourtable";
Statement st = sql.createStatement( ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY );
ResultSet rs = st.executeQuery(query);
int rows = 0;
rs.last();
rows = rs.getRow();
rs.beforeFirst();
System.out.println("Your query have " + rows + " rows.");
When you working with JDBC that does not support TYPE_FORWARD_ONLY use this method to get rowcount.
Statement s = cd.createStatement();
ResultSet r = s.executeQuery("SELECT COUNT(*) AS rowcount FROM TableName");
r.next();
int count = r.getInt("rowcount");
r.close();
System.out.println("MyTable has " + count + " row(s).");
You can Get Row count using above method.
Thanks..
In Android, having no results returns an error. So check this case before incrementing count in while(resultset.next())
if(resultset!=null)
{
//proceed with incrementing row count function
}
else
{
// No resultset found
}
Just iterate and count
ResultSet result = sta.executeQuery("SELECT * from A3");
int k=0;
while(result.next())
k++;
System.out.print(k); //k is the no of row
As method name specifies metaData.getColumnCount() will return total number of columns in result set but not total no of rows (count).
With java.sql.ResultSet is there a way to get a column's name as a String by using the column's index? I had a look through the API doc but I can't find anything.
You can get this info from the ResultSet metadata. See ResultSetMetaData
e.g.
ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
ResultSetMetaData rsmd = rs.getMetaData();
String name = rsmd.getColumnName(1);
and you can get the column name from there. If you do
select x as y from table
then rsmd.getColumnLabel() will get you the retrieved label name too.
In addition to the above answers, if you're working with a dynamic query and you want the column names but do not know how many columns there are, you can use the ResultSetMetaData object to get the number of columns first and then cycle through them.
Amending Brian's code:
ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
ResultSetMetaData rsmd = rs.getMetaData();
int columnCount = rsmd.getColumnCount();
// The column count starts from 1
for (int i = 1; i <= columnCount; i++ ) {
String name = rsmd.getColumnName(i);
// Do stuff with name
}
You can use the the ResultSetMetaData (http://java.sun.com/javase/6/docs/api/java/sql/ResultSetMetaData.html) object for that, like this:
ResultSet rs = stmt.executeQuery("SELECT * FROM table");
ResultSetMetaData rsmd = rs.getMetaData();
String firstColumnName = rsmd.getColumnName(1);
This question is old and so are the correct previous answers. But what I was looking for when I found this topic was something like this solution. Hopefully it helps someone.
// Loading required libraries
import java.util.*;
import java.sql.*;
public class MySQLExample {
public void run(String sql) {
// JDBC driver name and database URL
String JDBC_DRIVER = "com.mysql.jdbc.Driver";
String DB_URL = "jdbc:mysql://localhost/demo";
// Database credentials
String USER = "someuser"; // Fake of course.
String PASS = "somepass"; // This too!
Statement stmt = null;
ResultSet rs = null;
Connection conn = null;
Vector<String> columnNames = new Vector<String>();
try {
// Register JDBC driver
Class.forName(JDBC_DRIVER);
// Open a connection
conn = DriverManager.getConnection(DB_URL, USER, PASS);
// Execute SQL query
stmt = conn.createStatement();
rs = stmt.executeQuery(sql);
if (rs != null) {
ResultSetMetaData columns = rs.getMetaData();
int i = 0;
while (i < columns.getColumnCount()) {
i++;
System.out.print(columns.getColumnName(i) + "\t");
columnNames.add(columns.getColumnName(i));
}
System.out.print("\n");
while (rs.next()) {
for (i = 0; i < columnNames.size(); i++) {
System.out.print(rs.getString(columnNames.get(i))
+ "\t");
}
System.out.print("\n");
}
}
} catch (Exception e) {
System.out.println("Exception: " + e.toString());
}
finally {
try {
if (rs != null) {
rs.close();
}
if (stmt != null) {
stmt.close();
}
if (conn != null) {
conn.close();
}
} catch (Exception mysqlEx) {
System.out.println(mysqlEx.toString());
}
}
}
}
SQLite 3
Using getMetaData();
DatabaseMetaData md = conn.getMetaData();
ResultSet rset = md.getColumns(null, null, "your_table_name", null);
System.out.println("your_table_name");
while (rset.next())
{
System.out.println("\t" + rset.getString(4));
}
EDIT: This works with PostgreSQL as well
import java.sql.*;
public class JdbcGetColumnNames {
public static void main(String args[]) {
Connection con = null;
Statement st = null;
ResultSet rs = null;
try {
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/komal", "root", "root");
st = con.createStatement();
String sql = "select * from person";
rs = st.executeQuery(sql);
ResultSetMetaData metaData = rs.getMetaData();
int rowCount = metaData.getColumnCount();
System.out.println("Table Name : " + metaData.getTableName(2));
System.out.println("Field \tDataType");
for (int i = 0; i < rowCount; i++) {
System.out.print(metaData.getColumnName(i + 1) + " \t");
System.out.println(metaData.getColumnTypeName(i + 1));
}
} catch (Exception e) {
System.out.println(e);
}
}
}
Table Name : person
Field DataType
id VARCHAR
cname VARCHAR
dob DATE
while (rs.next()) {
for (int j = 1; j < columncount; j++) {
System.out.println( rsd.getColumnName(j) + "::" + rs.getString(j));
}
}
When you need the column names, but do not want to grab entries:
PreparedStatement stmt = connection.prepareStatement("SHOW COLUMNS FROM `yourTable`");
ResultSet set = stmt.executeQuery();
//store all of the columns names
List<String> names = new ArrayList<>();
while (set.next()) { names.add(set.getString("Field")); }
NOTE: Only works with MySQL
The SQL statements that read data from a database query return the data in a result set. The SELECT statement is the standard way to select rows from a database and view them in a result set. The **java.sql.ResultSet** interface represents the result set of a database query.
Get methods: used to view the data in the columns of the current row
being pointed to by the cursor.
Using MetaData of a result set to fetch the exact column count
ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
ResultSetMetaData rsmd = rs.getMetaData();
int numberOfColumns = rsmd.getColumnCount();
boolean b = rsmd.isSearchable(1);
http://docs.oracle.com/javase/7/docs/api/java/sql/ResultSetMetaData.html
and further more to bind it to data model table
public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
try {
//STEP 2: Register JDBC driver
Class.forName("com.mysql.jdbc.Driver");
//STEP 3: Open a connection
System.out.println("Connecting to a selected database...");
conn = DriverManager.getConnection(DB_URL, USER, PASS);
System.out.println("Connected database successfully...");
//STEP 4: Execute a query
System.out.println("Creating statement...");
stmt = conn.createStatement();
String sql = "SELECT id, first, last, age FROM Registration";
ResultSet rs = stmt.executeQuery(sql);
//STEP 5: Extract data from result set
while(rs.next()){
//Retrieve by column name
int id = rs.getInt("id");
int age = rs.getInt("age");
String first = rs.getString("first");
String last = rs.getString("last");
//Display values
System.out.print("ID: " + id);
System.out.print(", Age: " + age);
System.out.print(", First: " + first);
System.out.println(", Last: " + last);
}
rs.close();
} catch(SQLException se) {
//Handle errors for JDBC
se.printStackTrace();
} catch(Exception e) {
//Handle errors for Class.forName
e.printStackTrace();
} finally {
//finally block used to close resources
try {
if(stmt!=null)
conn.close();
} catch(SQLException se) {
} // do nothing
try {
if(conn!=null)
conn.close();
} catch(SQLException se) {
se.printStackTrace();
} //end finally try
}//end try
System.out.println("Goodbye!");
}//end main
//end JDBCExample
very nice tutorial here : http://www.tutorialspoint.com/jdbc/
ResultSetMetaData meta = resultset.getMetaData(); // for a valid resultset object after executing query
Integer columncount = meta.getColumnCount();
int count = 1 ; // start counting from 1 always
String[] columnNames = null;
while(columncount <=count) {
columnNames [i] = meta.getColumnName(i);
}
System.out.println (columnNames.size() ); //see the list and bind it to TableModel object. the to your jtbale.setModel(your_table_model);
#Cyntech is right.
Incase your table is empty and you still need to get table column names you can get your column as type Vector,see the following:
ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
ResultSetMetaData rsmd = rs.getMetaData();
int columnCount = rsmd.getColumnCount();
Vector<Vector<String>>tableVector = new Vector<Vector<String>>();
boolean isTableEmpty = true;
int col = 0;
while(rs.next())
{
isTableEmpty = false; //set to false since rs.next has data: this means the table is not empty
if(col != columnCount)
{
for(int x = 1;x <= columnCount;x++){
Vector<String> tFields = new Vector<String>();
tFields.add(rsmd.getColumnName(x).toString());
tableVector.add(tFields);
}
col = columnCount;
}
}
//if table is empty then get column names only
if(isTableEmpty){
for(int x=1;x<=colCount;x++){
Vector<String> tFields = new Vector<String>();
tFields.add(rsmd.getColumnName(x).toString());
tableVector.add(tFields);
}
}
rs.close();
stmt.close();
return tableVector;
ResultSet rsTst = hiSession.connection().prepareStatement(queryStr).executeQuery();
ResultSetMetaData meta = rsTst.getMetaData();
int columnCount = meta.getColumnCount();
// The column count starts from 1
String nameValuePair = "";
while (rsTst.next()) {
for (int i = 1; i < columnCount + 1; i++ ) {
String name = meta.getColumnName(i);
// Do stuff with name
String value = rsTst.getString(i); //.getObject(1);
nameValuePair = nameValuePair + name + "=" +value + ",";
//nameValuePair = nameValuePair + ", ";
}
nameValuePair = nameValuePair+"||" + "\t";
}
If you want to use spring jdbctemplate and don't want to deal with connection staff, you can use following:
jdbcTemplate.query("select * from books", new RowCallbackHandler() {
public void processRow(ResultSet resultSet) throws SQLException {
ResultSetMetaData rsmd = resultSet.getMetaData();
for (int i = 1; i <= rsmd.getColumnCount(); i++ ) {
String name = rsmd.getColumnName(i);
// Do stuff with name
}
}
});
U can get column name and value from resultSet.getMetaData();
This code work for me:
Connection conn = null;
PreparedStatement preparedStatement = null;
try {
Class.forName("com.mysql.cj.jdbc.Driver");
conn = MySQLJDBCUtil.getConnection();
preparedStatement = conn.prepareStatement(sql);
if (params != null) {
for (int i = 0; i < params.size(); i++) {
preparedStatement.setObject(i + 1, params.get(i).getSqlValue());
}
ResultSet resultSet = preparedStatement.executeQuery();
ResultSetMetaData md = resultSet.getMetaData();
while (resultSet.next()) {
int counter = md.getColumnCount();
String colName[] = new String[counter];
Map<String, Object> field = new HashMap<>();
for (int loop = 1; loop <= counter; loop++) {
int index = loop - 1;
colName[index] = md.getColumnLabel(loop);
field.put(colName[index], resultSet.getObject(colName[index]));
}
rows.add(field);
}
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
if (preparedStatement != null) {
try {
preparedStatement.close();
}catch (Exception e1) {
e1.printStackTrace();
}
}
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
return rows;
I know, this question is already answered but probably somebody like me needs to access a column name from DatabaseMetaData by label instead of index:
ResultSet resultSet = null;
DatabaseMetaData metaData = null;
try {
metaData = connection.getMetaData();
resultSet = metaData.getColumns(null, null, tableName, null);
while (resultSet.next()){
String name = resultSet.getString("COLUMN_NAME");
}
}