column not found !

Hello,
I am trying to retrive a record from pqsl DB using the
following steps.

First I prepare a String Buffer "prepareSql".

prepareSql.append("Select");

    if(req.getParameter("firstname") != null){
        prepareSql.append(" name,");
    }
    if(req.getParameter("city") != null){
        prepareSql.append(" city,");
    }
    if(req.getParameter("zip") != null){
        prepareSql.append(" zip,");
    }
    if(req.getParameter("country") != null){
        prepareSql.append(" country,");
    }
    if(req.getParameter("email") != null){
        prepareSql.append(" email,");
    }
    // Deleting the Coma at the end of an entity.
    int sbLength = prepareSql.length();
    prepareSql.deleteCharAt(sbLength - 1);

    prepareSql.append(" from Personal where immat = " +
Integer.parseInt(req.getParameter("immat")));
return prepareSql.toString();

Second I pass this string to a method thru a variable
"sql" and execute this statement.

stmt.executeQuery(sql);

To my information I did a System.out.println(sql);
and I got the result "Select name, zip, email from
Personal where immat = 500103"

I get the error "The column name immat not found." as
the SQL Execption.

I executed the same statement in the psql command line
it was executing it and displaying the record.

Can someone explain me what wrong I had made. I had
also attached the codes for your reference.

Thanks in advance.
Domnic

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