prestatement방식 , statement방식 차이.

DAO

package dao;

import java.sql.Connection;
import java.sql.DriverManager;

public class DAO {
	Connection con;
	
	public void getCon() {
		try {
			Class.forName("com.mysql.cj.jdbc.Driver");
			String url="jdbc:mysql://localhost:3306/p2";
			String user="root";
			String password="1111";
			
			con = DriverManager.getConnection(url, user, password);
			
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

MemberDAO

	Statement stmt;
	PreparedStatement pstmt;
	ResultSet rs;
		
	DAO d = new DAO();
    
    public Vector<Member> listAllMember(int startRow, int endRow, String field, String search ) {
		d.getCon();
		
		Vector<Member> list = new Vector<Member>();
		
		String str = "";
		if(search != null) { // 검색어 존재시
			str = " and "+field+" like '%"+search+"%' ";
		}
		
		try {
			String sql = "select * from member4 where (1) "+str+" limit ?,?";
			pstmt = d.con.prepareStatement(sql);
			pstmt.setInt(1, startRow);
			pstmt.setInt(2, endRow);
			rs = pstmt.executeQuery();
			
			while(rs.next()) {
				Member m = new Member();
				
				m.setId(rs.getString("id"));
				m.setPass(rs.getString("pass"));
				m.setName(rs.getString("name"));
				m.setAge(rs.getInt("age"));
				m.setGender(rs.getString("gender"));
				m.setEmail(rs.getString("email"));
				m.setLevel(rs.getString("level"));
				m.setFile1(rs.getString("file1"));
				
				list.add(m);
			}
			rs.close();
			pstmt.close();
			d.con.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
		return list;
	}

Statement방식

	String sql_counts = "(select "+s+" from free "+c+") UNION (select "+s+" from meet4 "+c+") UNION (select "+s+" from meet3 "+c+") UNION (select "+s+" from meet2 "+c+") UNION (select "+s+" from meet1 "+c+") UNION (select "+s+" from meet "+c+") UNION (select "+s+" from infor4 "+c+") UNION (select "+s+" from infor3 "+c+") UNION (select "+s+" from infor2 "+c+") UNION (select "+s+" from infor1 "+c+") UNION (select "+s+" from infor "+c+") UNION (select "+s+" from gallery4 "+c+") UNION (select "+s+" from gallery3 "+c+") UNION (select "+s+" from gallery2 "+c+") UNION (select "+s+" from gallery1 "+c+") UNION (select "+s+" from gallery "+c+") UNION (select "+s+" from qna4 "+c+") UNION (select "+s+" from qna3 "+c+") UNION (select "+s+" from qna2 "+c+") UNION (select "+s+" from qna1 "+c+") UNION (select "+s+" from qna "+c+") UNION (select "+s+" from free1 "+c+") UNION (select "+s+" from free2 "+c+") UNION (select "+s+" from free3 "+c+") UNION (select "+s+" from free4 where id = '"+session_id+"')";
//	out.print(sql_count);
	
	Connection con_counts = DriverManager.getConnection(url, user, password);
	Statement stmt_counts = con_counts.createStatement();
	ResultSet rs_counts = stmt_counts.executeQuery(sql_counts);
	int total_records = 0;
	int a = 0;
	while(rs_counts.next()){
		a = rs_counts.getInt("count");
		total_records += a;
	}
	rs_counts.close();
	stmt_counts.close();
	con_counts.close();