I'am trying to update table from multiple columns names(lo1,lo2,...) that are to be taken dynamically. But the values are not getting updated in database.
column names are co1,co2....
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
Connection conn = null;
PreparedStatement pstmt = null;
try{
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost/netbeans","root","");
Statement st = conn.createStatement();
ResultSet rs = st.executeQuery("SELECT * FROM colo");
rs = st.executeQuery("SELECT COUNT(*) FROM colo");
// get the number of rows from the result set
rs.next();
int rowCount = rs.getInt(1);
//txt_ans.setText(String.valueOf(rowCount));
int num_1 =300;
int num_2 =200;
int num_3 =300;
int num_4 =400;
String value = null;
int value1 ;
for(int i=1;i<=rowCount;i++)
{
String sql =("SELECT * FROM colo WHERE id = '"+i+"'");
pstmt = conn.prepareStatement(sql);
rs = pstmt.executeQuery(sql);
while(rs.next())
value = rs.getString("co1");
//txt_ans.setText(String.valueOf(value));
String x = "co2";
if(value.equals("lo1"))
{
// value1= 1;
// txt_ans.setText(String.valueOf(value1));
String sql1 =("update colo set '"+x+"' = '"+num_1+"' where id = '"+i+"'");
pstmt = conn.prepareStatement(sql1);
int r = pstmt.executeUpdate(sql1);
txt_ans.setText(String.valueOf(r));
}
else if(value.equals("lo2"))
{
// value1= 1;
// txt_ans.setText(String.valueOf(value1));
String sql1 =("update colo set '"+ x +"' = '"+num_2+"' where id = '"+i+"'");
pstmt = conn.prepareStatement(sql1);
int r = pstmt.executeUpdate(sql1);
txt_ans.setText(String.valueOf(r));
}
else
{
value1 = 9009;
txt_ans.setText(String.valueOf(value1));
}
}
The problem is with using single quotes for column name i.e, like 'x', so just remove them as shown below:
String sql1 =("update colo set " + x + " = ? where id = ?");//no single quote for x
pstmt = conn.prepareStatement(sql1);
pstmt.setString(1, num_1);
pstmt.setString(2, i);
int r = pstmt.executeUpdate(sql1);
Also, always use prepareStatement's setString, etc.. methods for setting the values which is recommended.
Apply the same concept for the other query inside the else if(value.equals("lo2")) block as well.
I have two loops in the code shown below. The problem is that the first loop iterates only once. It doesn't display all the data.
st = conn.createStatement();
rs = st.executeQuery("SELECT * from geopools");
while(rs.next()){
System.out.println(rs.getInt("id"));
rs = st.executeQuery("SELECT * from Geofields where id_pool='"+rs.getInt("id")+"'");
while (rs.next()) {
System.out.println(rs.getString("name")+"//");
}
}
It is because you use the same ResultSet. Use a separate ResultSet for the second iteration:
st = conn.createStatement();
rs = st.executeQuery("SELECT * from geopools");
while(rs.next()){
System.out.println(rs.getInt("id"));
ResultSet rs2 = st.executeQuery("SELECT * from Geofields where id_pool='"+rs.getInt("id")+"'");
while (rs2.next()) {
System.out.println(rs2.getString("name")+"//");
}
}
Yes. Your second loop consumes the ResultSet.
Imagine you are looping from 1 to 10:
int i = 1;
for(; i <= 10; ++i) {
doStuff();
}
It should be obvious that doStuff() is executed 10 times. Now we change that to your loop:
int i = 1;
for(; i <= 10; ++i) {
doStuff();
for(; i <= 10; ++i) {
doOtherStuff();
}
}
Now doStuff is executed once, then we enter the inner loop. That executes 10 times and increments i. When the inner loop exits, i is 11 and the outer loop condition is met, it exits immediately.
You are doing (almost) exactly the same thing, instead of i you have a ResultSet which has a number of rows. The first loop takes one row, and prints the id from that row. Then the inner loop consumes the rest of the rows.
it works very well, but when I added a third loop I get the same problem and this is my source code:
st = conn.createStatement();
rs = st.executeQuery("SELECT * from geopools");
int idPool=0;
int idField =0;
while(rs.next()){
DefaultMutableTreeNode treeNode = new DefaultMutableTreeNode("Pool : "+rs.getString("name"));
poolNode.add(treeNode);
idPool = rs.getInt("id");
st2 = conn.createStatement();
rs2 = st2.executeQuery("SELECT * from Geofields where id_pool='"+idPool+"'");
while (rs2.next()) {
DefaultMutableTreeNode fieldsNode = new DefaultMutableTreeNode("Field : "+rs2.getString("name"));
treeNode.add(fieldsNode);
idField = rs2.getInt("id");
st3 = conn.createStatement();
rs3 = st3.executeQuery("SELECT * from geofieldsproject where id_pool='"+idPool+"'");
while (rs3.next()) {
DefaultMutableTreeNode projectsNode = new DefaultMutableTreeNode("Field : "+rs3.getString("name"));
treeNode.add(projectsNode);
}
}
}
st = null;
rs = null;
st2 = null;
rs2 = null;
st3 = null;
rs3 = null;
I'm new to java.I have a SQL Query that gives the following output
logtime 2014-09-02 16:05:10.0
BL1_data_SS_ST 2
BL2_data_SS_ST 2
BL3_data_SS_ST 2
BL4_data_SS_ST 1
BL5_data_SS_ST 0
BL6_data_SS_ST 2
/* continues till BL27_data_SS_ST */
st1_prmt_status_p45 1
beam_current 110.58
beam_energy 2500.0635
I have only one row in my output and 31 columns. I'm using Java and JSP .
EDIT
The above result is retrieved by the following method
public String[][] beamline_Status() {
int i = 0;
try {
con = getConnection();
stmt = con.createStatement();
String sql = "SELECT TOP 1 c.logtime, a.BL1_data_SS_ST,a.BL2_data_SS_ST,a.BL3_data_SS_ST,a.BL4_data_SS_ST,a.BL5_data_SS_ST,a.BL6_data_SS_ST,a.BL7_data_SS_ST,a.BL8_data_SS_ST,a.BL9_data_SS_ST,a.BL10_data_SS_ST,a.BL11_data_SS_ST, a.BL12_data_SS_ST,a.BL13_data_SS_ST,a.BL14_data_SS_ST,a.BL15_data_SS_ST,a.BL16_data_SS_ST,a.BL17_data_SS_ST,a.BL18_data_SS_ST,a.BL19_data_SS_ST,a.BL20_data_SS_ST,a.BL21_data_SS_ST,a.BL22_data_SS_ST,a.BL23_data_SS_ST,a.BL24_data_SS_ST,a.BL25_data_SS_ST,a.BL26_data_SS_ST,a.BL27_data_SS_ST,b.st1_prmt_status_p45,c.beam_current,c.beam_energy from INDUS2_BLFE.dbo.main_BLFE_status a inner join INDUS2_MSIS.dbo.main_MSIS_status b on a.logtime=b.logtime inner join INDUS2_BDS.dbo.DCCT c on b.logtime=c.logtime ORDER BY c.logtime DESC ";
stmt.executeQuery(sql);
rs = stmt.getResultSet();
while (rs.next()) {
for (int j = 0; j < 31; j++) {
a[i][j] = rs.getString(j + 1);
}
}
} catch (Exception e) {
System.out.println("\nException (String code):" + e);
} finally {
closeConnection(stmt, rs, con);
}
return a;
}
Now I wan to define a method which retrieve values from the ResultSet where column values are either 0 or 1. How to do that.
EDIT 2
I'm trying to retrieve the column values from resultset where column value is 1 by following code:-
public String[][] beam_CurrentStatus() {
int i = 0;
try
{
con = getConnection();
stmt = con.createStatement();
String sql = "SELECT TOP 1 c.logtime, a.BL1_data_SS_ST,a.BL2_data_SS_ST,a.BL3_data_SS_ST,a.BL4_data_SS_ST,a.BL5_data_SS_ST,a.BL6_data_SS_ST,a.BL7_data_SS_ST,a.BL8_data_SS_ST,a.BL9_data_SS_ST,a.BL10_data_SS_ST,a.BL11_data_SS_ST, a.BL12_data_SS_ST,a.BL13_data_SS_ST,a.BL14_data_SS_ST,a.BL15_data_SS_ST,a.BL16_data_SS_ST,a.BL17_data_SS_ST,a.BL18_data_SS_ST,a.BL19_data_SS_ST,a.BL20_data_SS_ST,a.BL21_data_SS_ST,a.BL22_data_SS_ST,a.BL23_data_SS_ST,a.BL24_data_SS_ST,a.BL25_data_SS_ST,a.BL26_data_SS_ST,a.BL27_data_SS_ST,b.st1_prmt_status_p45,c.beam_current,c.beam_energy from INDUS2_BLFE.dbo.main_BLFE_status a inner join INDUS2_MSIS.dbo.main_MSIS_status b on a.logtime=b.logtime inner join INDUS2_BDS.dbo.DCCT c on b.logtime=c.logtime ORDER BY c.logtime DESC ";
stmt.executeQuery(sql);
rs = stmt.getResultSet();
while (rs.next()) {
for (int j = 1; j < 31; j++) {
if ((rs.getString(j)) == "1")
a[i][j] = rs.getString(j + 1);
}
}
} catch (Exception e) {
System.out.println("\nException in:" + e);
} finally {
closeConnection(stmt, rs, con);
}
return a;
}
But the result I'm getting of above code is
[[Ljava.lang.String;#ea25c1
If you want entire table in the ResultSet and then obtain only the first and second column out of it you can do like:
Statement stmt=conn.createStatement();
ResultSet rs= stmt.executeQuery("select * from tableName");
rs.getInt(1); //assuming your column is of compatible type
rs.getInt(2);
or the other way is that you retrieve only the first two columns from the DB into your ResultSet
I have the following snippet code:
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("select * from books");
ResultSetMetaData resMetaData = rs.getMetaData();
int nCols = resMetaData.getColumnCount();
for (int kCol = 1; kCol <= nCols; kCol++) {
System.out.println(resMetaData.getColumnName(kCol));
}
while (rs.next()) {
for (int kCol = 1; kCol <= nCols; kCol++) {
String s = null;
if (kCol == nCols){
Statement stmt1 = conn.createStatement();
ResultSet rs1 = stmt1.executeQuery("select category_name from categories where category_id = " + rs.getString(kCol));
s = rs1.getString(2);
}
else{
s = rs.getString(kCol);
}
System.out.println(s);
}
}
In my data base I have two tables: books and categories. In both table I have a column *category_id*. The code selects records from the table books. The *category_id* from this table matches the *category_id* from table categories. In this table I have one more row: category_name. I want that the app to write the name from the *category_name* that matches the category_id in table books. I tried but I failed. So, could you give me any idea ?
Thank you
In the below code I am copying resultset content to arraylist. First part of the wile loop i.e while(RS.next()) is returing the results but when cursor moves to
Next while loop i.e while(SR.next()) I am getting "result set is closed". Please help me where I am doing mistake.
String SSQ = "select DISTINCT S_NUMBER from OTG.S_R_VAL" +
" WHERE R_TS = (SELECT MAX(R_TS) FROM OTG.S_R_VAL) order by S_NUMBER";
String SDS = "SELECT DISTINCT S_NUMBER FROM OTG.S_R_VAL AS STG WHERE S_NUMBER NOT IN" +
"(SELECT S_NO FROM OTG.R_VAL AS REV WHERE STG.S_NUMBER = REV.S_NO )";
String SSR = "SELECT DISTINCT S_NO FROM OTG.R_VAL where S_NO != 'NULL' order by S_NO";
String SSO = "Select O_UID from OTG.OPTY where C_S_NO IN" +
"( SELECT DISTINCT S_NUMBER FROM OTG.S_R_VAL AS STG WHERE S_NUMBER NOT IN(SELECT S_NO FROM OTG.R_VAL AS REV WHERE STG.S_NUMBER = REV.S_NO ))";
//Statement statement;
try {
connection = DatabaseConnection.getCon();
statement = connection.createStatement();
statement1 = connection.createStatement();
statement2 = connection.createStatement();
statement3 = connection.createStatement();
statement4 = connection.createStatement();
ResultSet RS = statement1.executeQuery(selectQuery);
ResultSet DS = statement2.executeQuery(Distinct_SiebelNo);
ResultSet SR = statement3.executeQuery(SiebelNo_Rev);
ResultSet SO = statement4.executeQuery(selected_OppId);
ArrayList<String> RSList = new ArrayList<String>();
ArrayList<String> SRList = new ArrayList<String>();
/* ResultSetMetaData resultSetMetaData = RS.getMetaData();
int count = resultSetMetaData.getColumnCount();*/
int count=1;
System.out.println("******count********"+count);
while(RS.next()) {
int i = 1;
count=1;
while(i < count)
{
RSList.add(RS.getString(i++));
}
System.out.println(RS.getString("SIEBEL_NUMBER"));
RSList.add( RS.getString("SIEBEL_NUMBER"));
}
/* ResultSetMetaData resultSetMetaData1 = SR.getMetaData();
int count1 = resultSetMetaData1.getColumnCount();*/
int count1=1;
while(SR.next()) {
int i = 1;
while(i < count1)
{
SRList.add(SR.getString(i++));
}
System.out.println(SR.getString("SIEBEL_NO"));
SRList.add( SR.getString("SIEBEL_NO"));
}SR.close();
connection.commit();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
The logic of each loop is flawed.
int count=1;//Count is being set to one
while(RS.next()) {
int i = 1;//i is being set to one
count=1;//count again set to one
while(i < count) //condition will always fail as one is never less than one
{
RSList.add(RS.getString(i++));//Code is never Reached
}
System.out.println(RS.getString("SIEBEL_NUMBER"));
RSList.add( RS.getString("SIEBEL_NUMBER"));
}
The second while is not needed. Just use this:
int count = 1;
while(RS.next()) {
RSList.add(RS.getString(count++));
System.out.println(RS.getString("SIEBEL_NUMBER"));
RSList.add( RS.getString("SIEBEL_NUMBER"));
}
EDIT
int count1=1;
while(SR.next()) {
SRList.add(SR.getString(count1++));
System.out.println(SR.getString("SIEBEL_NO"));
SRList.add( SR.getString("SIEBEL_NO"));
}
EDIT 2:
for (String s : RSList)
for(String s1 : SRList)
if (s.equals(s1))
//Do what you need
You are using the first resultset (RS) in the second loop (System.out.println line)