Develop Reference

MySQLSyntaxErrorException in JAVA

Somebody please help me.I am doing things right but i am getting an error.It is a JAVA application linked to MYSQL wamp server.
ERROR:
com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'Chege' at line 1
MY CODE:
public class MyQuery {
public Connection getConnection() {
Connection con = null;
try {
con = DriverManager.getConnection("jdbc:mysql://"
+ "localhost:3306/employee_certificate", "root", "");
} catch (SQLException ex) {
Logger.getLogger(Query.class.getName())
.log(Level.SEVERE, null, ex);
}
return con;
}
public ArrayList<Item> getData(String EmpName) {
ArrayList<Item> list = new ArrayList<Item>();
Connection con = getConnection();
Statement st;
ResultSet rs;
try {
st = con.createStatement();
rs = st.executeQuery("SELECT Emp_Id, Emp_Name, Department "
+ "FROM staff WHERE Emp_Name = " + EmpName + " ");
Item I;
while (rs.next()) {
I = new Item(
rs.getString("Emp_Id"),
rs.getString("Emp_Name"),
rs.getString("Department"));
list.add(I);
}
} catch (SQLException ex) {
Logger.getLogger(Query.class.getName()).log(Level.SEVERE, null, ex);
}
return list;
}
}

Your query string is not correct. Should be something like the following:
rs=st.executeQuery("SELECT Emp_Id, Emp_Name, Department "
+ "FROM staff WHERE Emp_Name = '"+EmpName+"'");
But I'd recommend to use a PreparedStatement object for sending SQL statements to the database.
String query = "SELECT Emp_Id, Emp_Name, Department FROM staff WHERE Emp_Name = ?";
PreparedStatement preStatement = conn.prepareStatement(query);
preStatement.setString(1, EmpName);
ResultSet result = preStatement.executeQuery();
This approach is safer and more convenient.

You have a little problem in your query:
try {
st = con.createStatement();
//Add quotes 'YourString'
rs = st.executeQuery("SELECT Emp_Id, Emp_Name, Department "
+ "FROM staff WHERE Emp_Name = '" + EmpName + "' ");
Item I;
while (rs.next()) {
I = new Item(rs.getString("Emp_Id"), rs.getString("Emp_Name"), rs.getString("Department"));
list.add(I);
}
} catch (SQLException ex) {
Logger.getLogger(Query.class.getName()).log(Level.SEVERE, null, ex);
}
or for a safety Query use prepared statement:
try {
PreparedStatement ps = connection.prepareStatement("SELECT Emp_Id, Emp_Name, Department FROM staff WHERE Emp_Name = ?");
ps.setString(1, EmpName);
rs = ps.executeUpdate();
Item I;
while (rs.next()) {
I = new Item(rs.getString("Emp_Id"), rs.getString("Emp_Name"), rs.getString("Department"));
list.add(I);
}
} catch (SQLException ex) {
Logger.getLogger(Query.class.getName()).log(Level.SEVERE, null, ex);
}

How to make one mySQL's table column invisible

I am running a query on ID column but I don't want it to be visible in my frame/pane. How can I achieve this? Shall I make another table, is there a function in sql/mysql which allows to hide columns? I tried to google it but havent found anything yet.
Here is the code:
public void tableChanged(TableModelEvent e) {
int row = e.getFirstRow();
int col = e.getColumn();
model = (MyTableModel) e.getSource();
String stulpPav = model.getColumnName(col);
Object data = model.getValueAt(row, col);
Object studId = model.getValueAt(row, 0);
System.out.println("tableChanded works");
try {
new ImportData(stulpPav, data, studId);
} catch (ClassNotFoundException e1) {
e1.printStackTrace();
} catch (SQLException e1) {
e1.printStackTrace();
}
}
public class ImportData {
Connection connection = TableWithBottomLine.getConnection();
public ImportData(String a, Object b, Object c)
throws ClassNotFoundException, SQLException {
Statement stmt = null;
try {
String stulpPav = a;
String duom = b.toString();
String studId = c.toString();
System.out.println(duom);
connection.setAutoCommit(false);
stmt = connection.createStatement();
stmt.addBatch("update finance.fin set " + stulpPav + " = " + duom
+ " where ID = " + studId + ";");
stmt.executeBatch();
connection.commit();
} catch (BatchUpdateException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally {
if (stmt != null)
stmt.close();
connection.setAutoCommit(true);
System.out.println("Data was imported to database");
}
}
}
public class MyTableModel extends AbstractTableModel{
int rowCount;
Object data [][];
String columnNames [];
public MyTableModel() throws SQLException{
String query ="SELECT ID, tbl_Date as Date, Flat, Mobile, Food, Alcohol, Transport, Outdoor, Pauls_stuff, Income, Stuff FROM finance.fin";
ResultSet rs ;
Connection connection = TableWithBottomLine.getConnection();
Statement stmt = null;
stmt = connection.createStatement();
rs = stmt.executeQuery(query);
rs.last();
rowCount = rs.getRow();
data = new Object[rowCount][11];
rs = stmt.executeQuery(query);
for (int iEil = 0; iEil < rowCount; iEil++){
rs.next();
data[iEil][0] = rs.getInt("ID");
data[iEil][1] = rs.getDate("Date");
data[iEil][2] = rs.getFloat("Flat");
data[iEil][3] = rs.getFloat("Mobile");
data[iEil][4] = rs.getFloat("Food");
data[iEil][5] = rs.getFloat("Alcohol");
data[iEil][6] = rs.getFloat("Transport");
data[iEil][7] = rs.getFloat("Outdoor");
data[iEil][8] = rs.getFloat("Pauls_stuff");
data[iEil][9] = rs.getFloat("Income");
data[iEil][10] = rs.getFloat("Stuff");
}
String[] columnName = {"ID", "Date","Flat","Mobile"
,"Food","Alcohol","Transport", "Outdoor", "Pauls_stuff", "Income", "Stuff"};
columnNames = columnName;
}

This has solved my problem:
table.removeColumn(table.getColumnModel().getColumn(0));
I placed this in my class contructor. This lets remove the column from the view of the table but column 'ID' is still contained in the TableModel. I found that many people looking for an option to exclude specific column (like autoincrement) from SELECT statement in sql / mysql but the language itself doesn't have that feature. So I hope this solution will help others as well.

Don't put ID in the select part of the query
String query ="SELECT tbl_Date as Date, Flat, Mobile, Food, Alcohol, Transport,
Outdoor, Pauls_stuff, Income, Stuff FROM finance.fin";

Result set returns 3 rows but i am only able to print 2?

The code below gets the information i require from my database but is not printing out all of the information. Firstly i know it is getting all of the correct information from the table because i have tried the query in sql developer.
public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try {
conn = getConnection();
String query = "SELECT menu.menu_id, menu_title, dish.dish_id, dish_name, dish_description, dish_price, menu.week_no "
+ "FROM menu, dish, menu_allocation "
+ "WHERE menu.active = '1' "
+ "AND menu.menu_id = menu_allocation.menu_id "
+ "AND dish.dish_id = menu_allocation.dish_id "
+ "AND menu.week_no IN (09, 10, 11)";
stmt = conn.createStatement();
rs = stmt.executeQuery(query);
MenuList list = null;
while (rs.next()) {
list = new MenuList(rs);
System.out.println(rs.getRow());
}
for (int pos = 0; pos < list.size(); pos++) {
Menu menu = list.getMenuAt(pos);
System.out.println(menu.getDescription());
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
rs.close();
stmt.close();
conn.close();
} catch (SQLException e) {
}
}
}
The output from the terminal is as follows:
3 //Number of rows
Fish and Chips //3rd row
Chocolate Cake //2nd row
//Here should be 1st row
BUILD SUCCESSFUL (total time: 2 seconds)
Even though it says there are three rows it has only printed the two. Can anybody see if there is a problem with the above?

It's hard to be sure without seeing the code for the MenuList class but I don't think you need to loop over the ResultSet as MenuList does that for you.
As the MenuList constructor takes the ResultSet in rs as a parameter it probably loops over the ResultSet to create its entries. As you've already called rs.next() in the while of your loop the MenuList misses the first result.
I think you should replace all this:
MenuList list = null;
while (rs.next()) {
list = new MenuList(rs);
System.out.println(rs.getRow());
}
With:
MenuList list = new MenuList(rs);

I would suggest you use a debugger so you understand what your progam is doing.
You appear to be only keeping the last row loaded, so while you have 3 rows, you only keep the last. It appears you are getting two values from the last row.

public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try {
conn = getConnection();
String query = "SELECT menu.menu_id, menu_title, dish.dish_id, dish_name, dish_description, dish_price, menu.week_no "
+ "FROM menu, dish, menu_allocation "
+ "WHERE menu.active = '1' "
+ "AND menu.menu_id = menu_allocation.menu_id "
+ "AND dish.dish_id = menu_allocation.dish_id "
+ "AND menu.week_no IN (09, 10, 11)";
stmt = conn.createStatement();
rs = stmt.executeQuery(query);
MenuList[3] list = null;
int idx = 0; //Add index
while (rs.next()) {
list[idx] = new MenuList(rs); //use index
idx++; //increment index
System.out.println(rs.getRow());
}
for (int pos = 0; pos < list.size(); pos++) {
Menu menu = list.getMenuAt(pos);//Don't know that
//get menu by index
System.out.println(menu.getDescription());
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
rs.close();
stmt.close();
conn.close();
} catch (SQLException e) {
}
}
}

Can we use two queries using prepared statement in one method

Can we use two queries in one method while using prepared statement, I have tried using this but invalid column name exception is coming.
My code snippets is as follows.
public double getPayroll(){
ResultSet rs = null;
ResultSet rs2 = null;
Connection conn = null;
PreparedStatement pstmt = null;
try {
conn = getDBConnection();
int employeeId;
String q1 = "select e_salary,e_house_rent,e_conv_allow,e_id
from employee";
pstmt = conn.prepareStatement(q1);
rs = pstmt.executeQuery();
double dailyPay=0,basicPay=0,payroll2=0;
int houseRent=0,convAllow=0;
while (rs.next()) {
dailyPay = rs.getInt(1)*.03;
houseRent=rs.getInt(2);
convAllow=rs.getInt(3);
employeeId=rs.getInt(4);
}
String q2="select att_status from attendance where
e_id=employeeId";
pstmt = conn.prepareStatement(q2);
rs2 = pstmt.executeQuery();
int noOfPresents = 0;
while(rs2.next()){
noOfPresents+=1;
}
basicPay=dailyPay*noOfPresents;
payroll2+=basicPay+houseRent+convAllow;
return payroll2;
} catch (Exception e) {
e.printStackTrace();
return 0.0;
} finally {
try {
rs.close();
pstmt.close();
conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}

Your problem is that the sql in q2 assumes that there is a column named employeeId, but I suspect you want to insert the value of the variable employeeId.
Change it to
select att_status from attendance where e_id=?
Then execute
pstmt.setString(1, employeeId);
before executing pstmt.executeQuery();

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");
}
}