0901_Java : JDBC : Metadata 메타데이터

메타데이터 ?

- 부가적인 정보로, 컬럼명, 컬럼 타입, 컬럼폭, 등을 의미하여 ResultSet에서 얻어온다.

package metaEx;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;

import db_util.DBConn;

public class Ex001_MetaData {

	public static void main(String[] args) {
		Connection conn = null;
		PreparedStatement pstmt = null;
		ResultSet rs = null;
		ResultSetMetaData rsmd = null;

		try {
			conn = DBConn.getConnection();

			String sql = "SELECT * FROM score";

			pstmt = conn.prepareStatement(sql);
			rs = pstmt.executeQuery();
			rsmd = rs.getMetaData();

			// 컬럼수
			int cols = rsmd.getColumnCount();
			System.out.println("전체 컬럼 수 : " + cols);

			for (int i = 1; i <= cols; i++) {
				System.out.print("컬럼명 : " + rsmd.getColumnName(i) + "\t");
				System.out.print("컬럼타입명 : " + rsmd.getColumnTypeName(i) + "\t");
				System.out.println("컬럼폭 : " + rsmd.getPrecision(i));
			}
			System.out.println();

			// 데이터
			// 테이블의 숫자, 날짜 형등은 문자열로 가져올 수 있다.
			while (rs.next()) {
				for (int i = 1; i <= cols; i++) {
					System.out.print(rs.getString(i) + "\t");
				}
				System.out.println();
			}

		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (rs != null) {
				try {
					rs.close();
				} catch (Exception e2) {
				}
			}
			if (pstmt != null) {
				try {
					pstmt.close();
				} catch (Exception e2) {
				}
			}
		}

	}

}

---

package metaEx;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;

import db_util.DBConn;

public class Ex002_Matadata {

	public static void main(String[] args) {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		Connection conn = DBConn.getConnection();
		Statement stmt = null;
		ResultSet rs = null;
		ResultSetMetaData rsmd = null;

		String sql;

		try {
			System.out.print("쿼리 ? ");
			sql = br.readLine();
			sql = sql.trim();

			if (!sql.toUpperCase().startsWith("SELECT")) {
				System.out.println("SELECT 문만 가능합니다.");
				return;
			}

			stmt = conn.createStatement();
			rs = stmt.executeQuery(sql);
			rsmd = rs.getMetaData();

			int cols = rsmd.getColumnCount();
			for (int i = 1; i <= cols; i++) {
				System.out.print(rsmd.getColumnName(i) + "\t");
			}
			
			System.out.println();
			
			while (rs.next()) {
				for (int i = 1; i <= cols; i++) {
					System.out.print(rs.getString(i) + "\t");
				}
				System.out.println();
			}

		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (rs != null) {
				try {
					rs.close();
				} catch (Exception e2) {
				}
			}
			if (stmt != null) {
				try {
					stmt.close();
				} catch (Exception e2) {
				}
			}
		}

	}

}