JDBC 查询数据库增删改查

JDBC (Java Database Connectivity) 是一种 Java API，用于在 Java 应用程序中访问并操作关系型数据库。通过 JDBC，开发者可以实现数据库的 CRUD (Create, Read, Update, Delete) 操作。

**创建（Create）：**

Connection conn = DriverManager.getConnection(url, username, password);
Statement stmt = conn.createStatement();
String sql = "INSERT INTO table_name (column1, column2) VALUES (?, ?)";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setString(1, value1);
pstmt.setInt(2, value2);
pstmt.executeUpdate(); // 执行插入操作

**读取（Read）：**

ResultSet rs = stmt.executeQuery("SELECT * FROM table_name WHERE condition");
while (rs.next()) {
    String column1Value = rs.getString("column1");
    int column2Value = rs.getInt("column2");
    // 处理数据
}

**更新（Update）：**

String updateSql = "UPDATE table_name SET column1 = ?, column2 = ? WHERE id = ?";
pstmt.setString(1, newValue1);
pstmt.setInt(2, newValue2);
pstmt.setInt(3, id);
int rowsUpdated = pstmt.executeUpdate();

**删除（Delete）：**

String deleteSql = "DELETE FROM table_name WHERE id = ?";
pstmt.setInt(1, id);
int rowsDeleted = pstmt.executeUpdate();