JDBC PreparedStatement with ? for Columnname won't work

Question

In a university task I'm using JDBC to access a database. I wrote a finder-method that could find objects in a table by any value in any column that has integer values.

public ResultSet findSampleByAnyCol(String colName, Integer sampleId, Connection con) {
    ResultSet rs = null;
    String sql = "SELECT * FROM sample WHERE ? = ?"; 

    try(PreparedStatement pstmt = con.prepareStatement(sql)) {
        pstmt.setString(1, colName);
        pstmt.setInt(2, sampleId);
        rs = pstmt.executeQuery();          

    }catch(SQLException e) {
        e.printStackTrace();
    }

    return rs;
  }

I tested it and I'm sure the problem is that "?" for the colum nname doesn't work. The stack trace says "invalid number". But if I change the SQL statement to SELECT * FROM sample WHERE sampleid = ? it works fine.

score 0 · Accepted Answer · answered May 12 '18 at 09:35

0

Just found the answer here, it´s not possible to do that. The "?" is just for values. To have variable columnnames it´s inevitable to do it with an own string manipulation.

answered May 12 '18 at 09:35

Severus0191

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JDBC PreparedStatement with ? for Columnname won't work

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