Optimize data calling in JDBC onto JTable - java

currently I have data in MySQL server and I am calling the datas onto the JTable through JDBC. However there are 1369 rows and it seems that it has too much data for it to load. It usually takes 5 minutes to load. Are there anyways to optimize the process? This is my code(I apologize in advance for a messy code):
public class DataTable {
private String databaseName = "*****";
private String tableName = "******";
public void showDatabase(){
Connection conn = null;
DatabaseMetaData meta = null;
Statement stmt = null;
ResultSet rs = null;
int k = 0;
try{
Class.forName("com.mysql.jdbc.Driver").newInstance();
String connectionUrl = "jdbc:mysql://localhost:3306/" + databaseName;
String connectionUser = "*****";
String connectionPassword = "*****";
conn = DriverManager.getConnection(connectionUrl, connectionUser, connectionPassword);
stmt = conn.createStatement();
meta = conn.getMetaData();
dataSets(stmt, meta);
}catch(Exception e){
e.printStackTrace();
} finally{
try { if (rs != null) rs.close(); } catch (SQLException e) { e.printStackTrace(); }
try { if (stmt != null) stmt.close(); } catch (SQLException e) { e.printStackTrace(); }
try { if (conn != null) conn.close(); } catch (SQLException e) { e.printStackTrace(); }
}
}
//return the column size of the table
public int getColumnNumber(DatabaseMetaData meta, Statement stmt) throws SQLException
{
//ResultSet rs = meta.getColumns(null, null, "practiceexample", null);
ResultSet rs = stmt.executeQuery("SELECT * FROM " + tableName);
ResultSetMetaData rsmd = rs.getMetaData();
int columnsNumber = rsmd.getColumnCount();
return columnsNumber;
}
//return the rowNumber of the tables
public int getRowNumber(Statement stmt) throws SQLException
{
ResultSet rs = stmt.executeQuery("SELECT COUNT(*) FROM " + tableName);
int rowCount = 0;
while(rs.next()){
rowCount = rs.getInt(1);
}
return rowCount;
}
public void dataSets(Statement stmt, DatabaseMetaData meta) throws SQLException
{
String[] columnNames = new String[getColumnNumber(meta, stmt)];
String[][] dataSets = new String[getRowNumber(stmt)][columnNames.length];
ResultSet column = meta.getColumns(null, null, tableName, null);
int i = 0;
while(column.next())
{
columnNames[i] = column.getString("COLUMN_NAME");
//columnNames.add(i, column.getString("COLUMN_NAME"));
i++;
}
for(int j = 0; j < dataSets.length; j++)
{
String[] singleRowData = new String[columnNames.length];
ResultSet data = null;
for(int k = 0; k < columnNames.length; k++)
{
String columnName = columnNames[k];
data = stmt.executeQuery("SELECT " + columnName +
" FROM " + tableName + " LIMIT " + j + ", " + 1);
while(data.next())
{
singleRowData[k] = data.getString(columnName);
}
}
dataSets[j] = singleRowData;
}
SimpleTable table = new SimpleTable(columnNames, dataSets);
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
table.createAndShowGUI();
}
});
}
class SimpleTable{
String[] columns;
String[][] dataSets;
public SimpleTable(String[] columns, String[][] dataSets){
this.columns = columns;
this.dataSets = dataSets;
}
public void createAndShowGUI(){
JPanel gui = new JPanel(new BorderLayout(3, 3));
final JTable table = new JTable(new DefaultTableModel(dataSets, columns));
final JScrollPane scrollPane = new JScrollPane(table, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED
, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
Dimension dimension = table.getPreferredSize();
scrollPane.setPreferredSize(new Dimension(dimension.width, table.getRowHeight() * 30));
JPanel navigation = new JPanel(new FlowLayout(FlowLayout.CENTER));
JButton next = new JButton(">");
next.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
{
int height = table.getRowHeight() * (20-1);
JScrollBar bar = scrollPane.getVerticalScrollBar();
bar.setValue(bar.getValue() + height);
}
});
JButton previous = new JButton("<");
previous.addActionListener( new ActionListener(){
public void actionPerformed(ActionEvent ae) {
int height = table.getRowHeight()*(20-1);
JScrollBar bar = scrollPane.getVerticalScrollBar();
bar.setValue( bar.getValue()-height );
}
} );
navigation.add(previous);
navigation.add(next);
gui.add(scrollPane, BorderLayout.CENTER);
gui.add(navigation, BorderLayout.SOUTH);
JOptionPane.showMessageDialog(null, gui);
}
}
}

IMHO the root of the bad permormance is you unnecessarily query the database mutliple times to get the data (columns, rows, rows number, columns number, etc) you need:
To get columns number:
ResultSet rs = stmt.executeQuery("SELECT * FROM " + tableName);
To get rows number:
ResultSet rs = stmt.executeQuery("SELECT COUNT(*) FROM " + tableName);
To get rows (this is the worst beacuse it's inside a loop):
data = stmt.executeQuery("SELECT " + columnName + " FROM " + tableName + " LIMIT " + j + ", " + 1);
How to solve it
Just query the database once. A single ResultSet and its associated ResultSetMetaData should be enough to accomplish your goal. Additionaly, and as already suggested, use a SwingWorker to do database calls in a separate thread. For example:
final JTable table = new JTable();
SwingWorker<Void, TableModel> worker = new SwingWorker<Void, TableModel> () {
#Override
protected Void doInBackground() throws Exception {
ResultSet resultSet = stmt.executeQuery("SELECT * FROM " + tableName);
ResultSetMetaData metaData = resultSet.getMetaData();
int columnCount = metaData.getColumnCount(); // columns number
String[] columnNames = new String[columnCount];
for (int i = 1; i <= columnCount; i++) {
columnNames[i] = metaData.getColumnName(i); // fill columns names
}
resultSet.last();
int rowCount = resultSet.getRow(); // get rows number
resultSet.beforeFirst();
Object[][] data = new Object[rowCount][columnCount];
int currentRow = 0;
while (resultSet.next()) {
for (int currentColumn = 1; currentColumn <= columnCount; currentColumn++) {
data[currentRow][currentColumn - 1] = resultSet.getObject(currentColumn); // fill data set
}
currentRow++;
}
TableModel model = new DefaultTableModel(data, columnNames);
publish(model);
return null;
}
#Override
protected void process(List<TableModel> chunks) {
TableModel model = chunks.get(0);
table.setModel(model);
}
}
worker.execute();

Related

How to not duplicate when adding data in JTable

How to not duplicate when adding data in JTable because when I am adding in JTable it always duplicate the same data.
public void buyproduct() {
String name = code_cart1.getText();
try {
con = Connector.getConnection();
PreparedStatement pst = con.prepareStatement("SELECT `Code`, `Category`, `ProductName`, `Size`, `Quantity`, `Price`, `Sub-Total` FROM `product_table` WHERE Code = ?");
pst.setString(1, name);
rs = pst.executeQuery();
while (rs.next()) {
int currentqty = rs.getInt("Quantity");
int pricenew = Integer.parseInt(price_cart1.getText());
int qtynew = Integer.parseInt(quantity_cart1.getText());
int tot = pricenew * qtynew;
if (qtynew > currentqty || qtynew == 0) {
JOptionPane.showMessageDialog(this, "Out of Stock!");
} else {
DefaultTableModel model = (DefaultTableModel) cart_Display.getModel();
model.addRow(new Object[]{code_cart1.getText(),
category_cart1.getText(),
productname_cart1.getText(),
size_cart1.getText(),
quantity_cart1.getText(),
price_cart1.getText(),
tot});
int sum = 0;
for (int i = 0; i < cart_Display.getRowCount(); i++) {
sum = sum + Integer.parseInt(cart_Display.getValueAt(i, 6).toString());
}
SubTotal_Cart_text.setText(Integer.toString(sum));
SubTotal_Cart_text1.setText(Integer.toString(sum));
code_cart1.setText("");
category_cart1.setText("");
productname_cart1.setText("");
size_cart1.setText("");
quantity_cart1.setText("");
price_cart1.setText("");
}
}
} catch(Exception ex) {
}
}

How to paint an image in Jtable with Mysql

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 .

Unable to display header for jTable

These are my codes for my jTable in java swing.
private JTable getJTable() {
if (jTable == null) {
Vector columnNames = new Vector(); //Vector class allows dynamic array of objects
Vector data = new Vector();
JPanel panel = new JPanel();
panel.setSize(new Dimension(198, 106));
try {
DBController db = new DBController();
db.setUp("IT Innovation Project");
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance();
String dsn = "IT Innovation Project";
String s = "jdbc:odbc:" + dsn;
Connection con = DriverManager.getConnection(s, "", "");
String sql = "Select * from forumTopics";
java.sql.Statement statement = con.createStatement();
ResultSet resultSet = statement.executeQuery(sql);
ResultSetMetaData metaData = resultSet.getMetaData();
int columns = metaData.getColumnCount();
for (int i = 1; i <= columns; i++) {
columnNames.addElement(metaData.getColumnName(i));
}
while (resultSet.next()) {
Vector row = new Vector(columns);
for (int i = 1; i <= columns; i++) {
row.addElement(resultSet.getObject(i));
}
data.addElement(row);
}
resultSet.close();
((Connection) statement).close();
} catch (Exception e) {
System.out.println(e);
}
jTable = new JTable(data, columnNames);
TableColumn column;
for (int i = 0; i < jTable.getColumnCount(); i++) {
column = jTable.getColumnModel().getColumn(i);
column.setMaxWidth(250);
}
String header[] = {"description", "title", "category", "posted by"};
for(int i=0;i<jTable.getColumnCount();i++) {
TableColumn column1 = jTable.getTableHeader().getColumnModel().getColumn(i);
column1.setHeaderValue(header[i]);
}
jTable.setBounds(new Rectangle(82, 218, 736, 292));
jTable.setEnabled(false);
jTable.setRowHeight(50);
jTable.getRowHeight();
}
return jTable;
}
I set an array for the header of my table. However, the program only shows the data inside my database without any header. Can somebody please enlighten me? Thanks in advance.
Put your JTable in JScrollPane like
add(new JScrollPane( getJTable() ) );

How to display search result in jtable?

I am using netbeans IDE. I like to check how canni actually search from a jtable which is mapped to a table using netbeans binding. I want to refresh the jtable showing records that matches my search criteria
DefaultTableModel model = new DefaultTableModel( results from your search );
table.setModel( model );
Edit: See Table From Database.
First i get the field names in a Jcombo box.
private void Text1KeyReleased(java.awt.event.KeyEvent evt) {
JTetclear();
Connection con = null;
Statement stmt = null;
try {
con = javaconnect.MySqlServer();
stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("SELECT * FROM `" + Combo1.getSelectedItem() + "` where `" + Combo2.getItemAt(0).toString() + "` Like '%" + Text1.getText() + "%' or `" + Combo2.getItemAt(1).toString() + "` Like '%" + Text1.getText() + "%' or `" + Combo2.getItemAt(2).toString() + "` Like '%" + Text1.getText() + "%' or `" + Combo2.getItemAt(0).toString() + "` Like '%" + Text1.getText() + "%' order by PARTNO;");
ResultSetMetaData md = rs.getMetaData();
DefaultTableModel tm = (DefaultTableModel) Table1.getModel(); // for changing column and row model
Combo2.removeAllItems();
tm.setColumnCount(0); tm.setRowCount(0); // clear existing columns and clear existing rows
for (int i = 1; i <= md.getColumnCount(); i++) {
tm.addColumn(md.getColumnName(i));
Combo2.addItem(md.getColumnName(i));//l load the column name in the combobox
}
tm.setRowCount(0); // clear existing rows
while (rs.next()) { // Get row data
Vector row = new Vector(md.getColumnCount());
for (int i = 1; i <= md.getColumnCount(); i++) {
row.addElement(rs.getObject(i));
}
tm.addRow(row);
Table1.getColumnModel().getColumn(0).setPreferredWidth(160);
Table1.getColumnModel().getColumn(1).setPreferredWidth(380);
}
rs.close();
stmt.close();
} catch (Exception ex) {
JOptionPane.showMessageDialog(this, ex, ex.getMessage(), WIDTH, null);
}
}
This is how i did it. Not an expert.
A method that returns result set:
public ResultSet actualInventoryInCencos(int idCencos) throws SQLException {
try {
SQL sql = new SQL();
PreparedStatement selectPS = sql.createPStatement(cf.SELECT_INVENTORY_BY_CENCOS);
selectPS.setInt(1, idCencos);
ResultSet resultSet = selectPS.executeQuery();
return resultSet;
} catch (SQLException | NullPointerException e) {
System.out.println(cf.ERROR_SQL + e);
cf.e(1);
return null;
}
}
Method in TableDAO that accepts the result set and make and returns a DefaultTableModel with all the query data.
public DefaultTableModel createTable(ResultSet rs) throws SQLException {
ResultSetMetaData metaData = rs.getMetaData();
int columnCount = metaData.getColumnCount();
//ColumnsNames
Vector<String> columnsNames = new Vector<>();
columnsNames.add("Column1");
columnsNames.add("Column2");
columnsNames.add("Column3");
Vector<Vector<Object>> tableData = new Vector<>();
while (rs.next()) {
Vector<Object> vector = new Vector<>();
for (int columnIndex = 1; columnIndex <= columnCount; columnIndex++) {
vector.add(rs.getObject(columnIndex));
}
tableData.add(vector);
}
return new DefaultTableModel(tableData, columnsNames);
}
And the line to set the New Model to your JTable:
yourJTable.setModel(tableDAO.createTable(inventory.actualInventoryInCencos(userData.getUserId())));

Retrieve column names from java.sql.ResultSet

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");
}
}

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