spring-boot-demo/db-migrations-flyway-liquibase/src/test/java/com/ankurm/dbmigrations/DbDump.java

package com.ankurm.dbmigrations;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

/** Renders a JDBC query as a plain-text table for transcripts — no ORM, no formatting library. */
public final class DbDump {

    private DbDump() {
    }

    public static String table(Connection conn, String sql) {
        try (Statement st = conn.createStatement(); ResultSet rs = st.executeQuery(sql)) {
            ResultSetMetaData meta = rs.getMetaData();
            int cols = meta.getColumnCount();
            List<String> headers = new ArrayList<>();
            for (int i = 1; i <= cols; i++) {
                headers.add(meta.getColumnLabel(i));
            }
            List<List<String>> rows = new ArrayList<>();
            while (rs.next()) {
                List<String> row = new ArrayList<>();
                for (int i = 1; i <= cols; i++) {
                    Object v = rs.getObject(i);
                    row.add(v == null ? "NULL" : v.toString());
                }
                rows.add(row);
            }
            int[] widths = new int[cols];
            for (int i = 0; i < cols; i++) {
                widths[i] = headers.get(i).length();
            }
            for (List<String> row : rows) {
                for (int i = 0; i < cols; i++) {
                    widths[i] = Math.max(widths[i], row.get(i).length());
                }
            }
            StringBuilder sb = new StringBuilder();
            appendRow(sb, headers, widths);
            StringBuilder sep = new StringBuilder();
            for (int i = 0; i < cols; i++) {
                sep.append("-".repeat(widths[i])).append(i < cols - 1 ? "-+-" : "");
            }
            sb.append(sep).append(System.lineSeparator());
            for (List<String> row : rows) {
                appendRow(sb, row, widths);
            }
            sb.append("(").append(rows.size()).append(" row").append(rows.size() == 1 ? "" : "s").append(")");
            return sb.toString();
        }
        catch (SQLException ex) {
            return "query failed: " + ex.getMessage();
        }
    }

    private static void appendRow(StringBuilder sb, List<String> values, int[] widths) {
        for (int i = 0; i < values.size(); i++) {
            sb.append(pad(values.get(i), widths[i]));
            sb.append(i < values.size() - 1 ? " | " : "");
        }
        sb.append(System.lineSeparator());
    }

    private static String pad(String s, int width) {
        return s + " ".repeat(Math.max(0, width - s.length()));
    }
}