java - 使用元数据在 mysql 中插入查询

Question

我有一个由表的列名组成的列表

String tableName="employee";
ResultSet rs = Statement.executeQuery("SELECT * FROM"+tableName);
    ResultSetMetaData   rmd = rs.getMetaData();
        int columnCount = rmd.getColumnCount();
        List columnsList = new ArrayList();
        for (int i = 1; i <= columnCount; i++) {
            columnsList.add(rmd.getColumnName(i));
        }

列出值=[一些值];

now columnsList =[emp_id, name, salary, department];

现在我想使用这些列名编写插入查询。但我不想对列名进行硬编码，我想从列表中获取这些名称并将它们传递给列名，例如

   String subQuery= "insert into"+tableName+......here i want to get column names from list.....+.......here values from another list......;

有什么办法可以得到这个吗

Answer 1

一直在谷歌搜索我的#@$寻找代码shippet来动态生成元数据形式的JDBC插入语句。引用generateInsertStatements()

private static void generateInsertStatements(Connection conn, String tableName)
throws Exception {
    log("Generating Insert statements for: " + tableName);
    Statement stmt = conn.createStatement();
    ResultSet rs = stmt.executeQuery("SELECT * FROM " + tableName); 
    ResultSetMetaData rsmd = rs.getMetaData();
    int numColumns = rsmd.getColumnCount();
    int[] columnTypes = new int[numColumns];
    String columnNames = "";
    for (int i = 0; i < numColumns; i++) {
        columnTypes[i] = rsmd.getColumnType(i + 1);
        if (i != 0) {
            columnNames += ",";
        }
        columnNames += rsmd.getColumnName(i + 1);
    }

    java.util.Date d = null; 
    PrintWriter p = new PrintWriter(new FileWriter(tableName + "_insert.sql"));
    p.println("set sqlt off");
    p.println("set sqlblanklines on");
    p.println("set define off");
    while (rs.next()) {
        String columnValues = "";
        for (int i = 0; i < numColumns; i++) {
            if (i != 0) {
                columnValues += ",";
            }

            switch (columnTypes[i]) {
                case Types.BIGINT:
                case Types.BIT:
                case Types.BOOLEAN:
                case Types.DECIMAL:
                case Types.DOUBLE:
                case Types.FLOAT:
                case Types.INTEGER:
                case Types.SMALLINT:
                case Types.TINYINT:
                    String v = rs.getString(i + 1);
                    columnValues += v;
                    break;

                case Types.DATE:
                    d = rs.getDate(i + 1); 
                case Types.TIME:
                    if (d == null) d = rs.getTime(i + 1);
                case Types.TIMESTAMP:
                    if (d == null) d = rs.getTimestamp(i + 1);

                    if (d == null) {
                        columnValues += "null";
                    }
                    else {
                        columnValues += "TO_DATE('"
                                  + dateFormat.format(d)
                                  + "', 'YYYY/MM/DD HH24:MI:SS')";
                    }
                    break;

                default:
                    v = rs.getString(i + 1);
                    if (v != null) {
                        columnValues += "'" + v.replaceAll("'", "''") + "'";
                    }
                    else {
                        columnValues += "null";
                    }
                    break;
            }
        }
        p.println(String.format("INSERT INTO %s (%s) values (%s)\n/", 
                                tableName,
                                columnNames,
                                columnValues));
    }
    p.close();
}

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