如何在使用JDBC的SELECT查询中使用动态表名

Question

我有5或表来查询\

我的语法我喜欢这个

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
}

问题是,当我运行这个时,我得到一个错误,说"你有SQL语法附近的错误吗？WHERE Patient_ID =？"

当我使用system.out.println(sql2)输出sql时;

sql2中未设置值

Answer 1

准备语句时,数据库会构造一个执行计划,如果表不存在,则无法执行该计划.换句话说,placehodlers只能用于值,而不能用于对象名称或保留字.在这种情况下,您必须依赖Java来构造字符串:

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

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