java - How to use dynamic table name in SELECT query using JDBC

Question

I have 5 or table table to query from

my syntax i like this

String sql2 = "SELECT * FROM ? WHERE Patient_ID = ?";

pst = conn.prepareStatement(sql2);

        System.out.println("SQL before values are set "+sql2);
        System.out.println("The values of table/test name recieved in TestPrint stage 1 "+tblName);
        System.out.println("The values of test name recieved in TestPrint stage 1 "+key);
        // values are outputted correctly but are not getting set in the query

        pst.setString(1, tblName);
        pst.setLong(2, key);
ResultSet rs2 = pst.executeQuery(sql2);

        while(rs2.next()){

            String ID = rs2.getString("ID");

            jLabel35.setText(ID);
            jLabel37.setText(ID);
            jLabel38.setText(ID);
       // them print command is initiated to print the panel
}

The problem is when i run this i get an error saying ".....you have and error in SQL syntax near ? WHERE Patient_ID = ?"

When i output the sql using system.out.println(sql2);

values are not set in sql2

Answer 1

When you prepare a statement, the database constructs an execution plan, which it cannot do if the table is not there. In other words, placehodlers can only be used for values, not for object names or reserved words. You'd have to rely on Java to construct your string in such a case:

String sql = "SELECT * FROM `" + tblName + "` WHERE Patient_ID = ?";

pst = conn.prepareStatement(sql);
pst.setLong(1, key);
ResultSet rs = pst.executeQuery(sql);