Why have to append spaces when data type is char?

Question

I have a tabe MyTable which has tow columns(code char(8),name varchar2(16)) and there is one record ('003','mike') in the table,I retrieve the table use the code :
......//get database connection
String sql = "SELECT * FROM MyTable where code = ?";
PreparedStatement st = conn.prepareStatement(sql);
st.setString(1,"003");
ResultSet rs = st.executeQuery();
......//other code
I cann't retrieve the record,I have to append 5 space to the parameter to get data: st.setString(1,"003 ").
When column's data type is char , I have to append spaces to the parameter values? why?

Answer 1

or if you want to do it at the API level, you can use the Oracle extension
OraclePreparedStatement.setFixedCHAR
public void setFixedCHAR(int paramIndex,
                         java.lang.String x)
                  throws java.sql.SQLException
    Use this method when binding to a CHAR column in the
where clause of a Select statement. A non padded
comparision will be done unlike in setCHAR and setString
case. Not particularly needed for an insert as the
database will pad it.
Parameters:
paramIndex - index of the bind variablex - the literal/variable to be bound.like..,
String sql = "SELECT * FROM MyTable where code = ?";
PreparedStatement st = conn.prepareStatement(sql);
((oracle.jdbc.OraclePreparedStatement)st).setFixedCHAR(1, "003");
pstmt.executeQuery();Regards
Elango.