How can I check if a string is available in a table?

mmuncada Published at Dev

mmuncada

Here's the table (tblemployees) How can I convert my code that used text files to a code that will use database (tables).

int intcurrentLine = -1;
String[] strLineSplit = (sb.toString()).split("\\r?\\n"); // converts sb to string then splits it by line
int intNumElements = strLineSplit.length; // number of elements
while (intcurrentLine != (intNumElements - 1)) {
    intcurrentLine++;
    String[] strWords = (strLineSplit[intcurrentLine]).split(" ", 2); // splits the current line by the first instance(space)
    if (strEmpID.equals(strWords[0])) { // checks if the employee ID is available
        JOptionPane.showMessageDialog(null, "Welcome " + strWords[1] + ", you have successfully logged in.");
        strCheck = 1; // to confirm and go to time in and out process
        break;
    }
    if ((intcurrentLine + 1) == intNumElements) { // condition to state that ID cant be found from the employee list
        JOptionPane.showMessageDialog(null, "No such employee, please check the ID No. that you entered.");
    }
}

Now I would like to search a column if it contains an Employee number. How do I put it to a condition, I've been searching but unable to find a clear answer. They only put how to search like this

String queryCheck = "SELECT * from messages WHERE EmpIDNo = 'COMSCI0001'";
ResultSet res = st.executeQuery(queryCheck);

then I'm lost, how to make a condition where if the employee no. doesn't exists something would happen else something would happen. I'm just confuse how to make a condition for that.

janos

You can do like this:

String queryCheck = "SELECT * FROM messages WHERE EmpIDNo = 'COMSCI0001' LIMIT 1";
ResultSet res = st.executeQuery(queryCheck);
boolean exists = res.next();

The boolean variable exists will indicate whether a matching record exists or not.

Notice that I added LIMIT 1 at the end of the SQL as an optimization to avoid fetching more data than you really need.

Collected from the Internet

Please contact [email protected] to delete if infringement.