Develop Reference

Syntax for SQL statement using mysql database

public void insertTags(Elements[] elements) {
Connection con = (Connection) DbConnection.getConnection();
try {
String sql = "insert into htmltags(source) values(?),(?),(?)";
PreparedStatement ps = (PreparedStatement) con.prepareStatement(sql);
ps.setString(1, elements[0].toString());
ps.setString(2, elements[1].toString());
ps.setString(3, elements[2].toString());
int rs = ps.executeUpdate(sql);
System.out.println("Data inserted" + rs);
} catch (SQLException e) {
e.printStackTrace();
}
}
is this a valid syntax for Prepared statement.

This is your problem:
int rs = ps.executeUpdate(sql);
From the JavaDoc we see that PreparedStatement#executeUpdate() does not take any parameters. The reason is that we already passed the query earlier when preparing the statement. Your code should be this:
int rs = ps.executeUpdate(); // no parameter
Also no need to cast the result of prepareStatement to PrepareStatement

To insert multiple values, I don't thing using values(?),(?),(?) is the right syntax, instead use a loop, or for better way you can use batch :
String sql = "insert into htmltags(source) values(?)";
try (PreparedStatement ps = con.prepareStatement(sql);) {
for (Elements element : elements) {
ps.setString(1, element.toString());
ps.addBatch();//Add a new batch for each Element
}
int[] result = ps.executeBatch();//Submits a batch of commands to the database
} catch (SQLException e) {
e.printStackTrace();
}

Java + SQL Server: Resultset is null?

I am new to using java with a database and I have been trying following code:
public int getDateDiff(int OrderID) {
Connection conn = DBConnection.getConnection();
Integer diff = null;
String getdiffSQL = "SELECT DATEDIFF( DAY , StartDate , EndDate ) FROM CarOrder WHERE OrderID = ?;";
try {
PreparedStatement pstm = conn.prepareStatement(getdiffSQL);
pstm.setInt(1, OrderID);
ResultSet rs = pstm.executeQuery(getdiffSQL);
while (rs.next()) {
diff = rs.getInt(1);
}
}
catch (SQLException ex) {
System.out.println("Error: " + ex.getMessage());
}
return diff;
}
I tried running this but i encounter this
"Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException"
and the the return diff is null. Please tell me what wrong in this and how do i fix this.

PreparedStatement#executeQuery() does not take a parameter and you should not be passing the query string. Instead use this pattern:
PreparedStatement pstm = conn.prepareStatement(getdiffSQL);
pstm.setInt(1, OrderID);
ResultSet rs = pstm.executeQuery(); // no parameter
This is a fairly common mistake made when using JDBC, partly because Statement#executeQuery() does take the query string as a parameter. Add to this tutorials like MkYong which make the same mistake as the OP and it is easy to see why this error is so prevalant.

PSQLException thrown when trying to execute SELECT query

I have problem with my SQL request, when I run my request, I receive this message error:
org.postgresql.util.PSQLException: A result was returned when none was expected.
Here is my request:
Connexion con = new Connexion();
try {
c = con.Connect();
stmt = c.createStatement();
int sqlCalcul = stmt.executeUpdate(
"SELECT inventaire FROM calcul WHERE designation='" + designation +
"' AND date=(SELECT MAX(date) FROM calcul)");
stmt.close();
// c.commit();
c.close();
} catch (Exception e) {
System.err.println(e.getClass().getName() + ": " + e.getMessage());
System.exit(0);
}
System.out.println("Records created successfully");

You should use executeQuery instead of executeUpdate:
ResultSet sqlCalcul = stmt.executeQuery("SELECT inventaire...")
executeUpdate is used for a INSERT, UPDATE, or DELETE statement, and will throw an exception if a ResultSet is returned. executeQuery should be used for SELECT statements.
Take a look at PostgreSQL's tutorial using the JDBC driver for more information.

Database Java Bean SQL Statement

In my database bean I have a section of code which is below :
public Integer getTotalOrgPoints() {
try {
PreparedStatement stmt = ConnectionHandler.getConnection().prepareStatement(QUERY_TOTAL_ORG_SCORE);
ResultSet rs = stmt.executeQuery();
while (rs.next()) {
totalOrgPoints = rs.getInt(1);
}
} catch (SQLException e) {
System.out.println(e.getMessage());
}
return totalOrgPoints;
}
For the statement QUERY_TOTAL_ORG_SCORE if I use
SELECT SUM(users.score)
FROM user_organisation_relationships
INNER JOIN users
ON user_organisation_relationships.user_id = users.id
WHERE organisation_id = 1
It will return the value for that organisation but if I use
SELECT SUM(users.score)
FROM user_organisation_relationships
INNER JOIN users
ON user_organisation_relationships.user_id = users.id
WHERE organisation_id = ?
I get nothing does anyone know why this is happening for me?.

Add this line to bind values for prepared statement before executequery
stmt.setInt(1, 1);
Modified:-
PreparedStatement stmt = ConnectionHandler.getConnection().prepareStatement(QUERY_TOTAL_ORG_SCORE);
stmt.setInt(1, 1);
ResultSet rs = stmt.executeQuery();

How to call Stored Procedure and prepared statement

In the below code I want to call one stored procedures and execute one Query. I am facing error at statement.executeUpdate(); Please help in fixing it. I am not sure where it going wrong.
public void Dbexe() {
Connection connection;
connection = DatabaseConnection.getCon();
CallableStatement stmt;
try {
stmt = connection.prepareCall("{CALL optg.Ld_SOpp}");
stmt.executeUpdate();
stmt.close();
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
System.out.println("Stored Procedure executed");
//PreparedStatement statement = null;
// ResultSet rs = null;
try{
PreparedStatement statement;
try {
statement = connection.prepareStatement("MERGE INTO OPTG.R_VAL AS TARGET USING" +
........... +
"");
statement.executeUpdate(); //Here the exception is thrown
statement.close();
connection.commit();
connection.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// statement = connection.prepareStatement(query);
//statement.close();
}
finally{
System.out.println("Data is copied to the Table");
}
}

Little off-topic: You should use CallableStatement instead if you want to call a store procedure (see documentation):
CallableStatement callableStatement = connection.prepareCall("{call opptymgmt.Load_SiebelOpportunity}");
ResultSet rs = callableStatement.executeQuery();
I would also suggest you check this topic How to properly clean up JDBC resources in Java?. It was very helpful to me.
Update: based on this stack trace:
com.ibm.db2.jcc.am.mo: DB2 SQL Error: SQLCODE=-104, SQLSTATE=42601, SQLERRMC=MERGE INTO OPPTYMGMT.REVENUE_VALIDAT;BEGIN-OF-STATEMENT;<variable_set>, DRIVER=4.7.85
The problem seems to be in the sql sentence you're trying to execute. I mean, is an error from DB2, not java. You should check your sql statement.

I got it working in this method:
PreparedStatement myStmt = conn.prepareStatement(sqlQuery);
myStmt.setInt(1, id); //position of parameter (1,2,3....) , value
ResultSet rs = myStmt.executeQuery();
while (rs.next()) {
int jobId = rs.getInt("jobId"); ....... }