使用ManagedDataAccess.dll构建增删改查语句

使用ManagedDataAccess.dll可以很方便地构建增删改查语句，以下是一些示例代码：

1. 插入数据：

string connectionString = "Data Source=myServerAddress;Initial Catalog=myDataBase;User ID=myUsername;Password=myPassword;";
string insertQuery = "INSERT INTO myTable (column1, column2, column3) VALUES (@val1, @val2, @val3)";

using (OracleConnection connection = new OracleConnection(connectionString))
{
    using (OracleCommand command = new OracleCommand(insertQuery, connection))
    {
        command.Parameters.Add("@val1", OracleDbType.Varchar2).Value = "value1";
        command.Parameters.Add("@val2", OracleDbType.Varchar2).Value = "value2";
        command.Parameters.Add("@val3", OracleDbType.Varchar2).Value = "value3";

        connection.Open();
        command.ExecuteNonQuery();
    }
}

2. 更新数据：

string connectionString = "Data Source=myServerAddress;Initial Catalog=myDataBase;User ID=myUsername;Password=myPassword;";
string updateQuery = "UPDATE myTable SET column1 = @val1 WHERE column2 = @val2";

using (OracleConnection connection = new OracleConnection(connectionString))
{
    using (OracleCommand command = new OracleCommand(updateQuery, connection))
    {
        command.Parameters.Add("@val1", OracleDbType.Varchar2).Value = "new_value";
        command.Parameters.Add("@val2", OracleDbType.Varchar2).Value = "old_value";

        connection.Open();
        command.ExecuteNonQuery();
    }
}

3. 删除数据：

string connectionString = "Data Source=myServerAddress;Initial Catalog=myDataBase;User ID=myUsername;Password=myPassword;";
string deleteQuery = "DELETE FROM myTable WHERE column1 = @val1";

using (OracleConnection connection = new OracleConnection(connectionString))
{
    using (OracleCommand command = new OracleCommand(deleteQuery, connection))
    {
        command.Parameters.Add("@val1", OracleDbType.Varchar2).Value = "value_to_delete";

        connection.Open();
        command.ExecuteNonQuery();
    }
}

4. 查询数据：

string connectionString = "Data Source=myServerAddress;Initial Catalog=myDataBase;User ID=myUsername;Password=myPassword;";
string selectQuery = "SELECT * FROM myTable WHERE column1 = @val1";

using (OracleConnection connection = new OracleConnection(connectionString))
{
    using (OracleCommand command = new OracleCommand(selectQuery, connection))
    {
        command.Parameters.Add("@val1", OracleDbType.Varchar2).Value = "value_to_select";

        connection.Open();

        using (OracleDataReader reader = command.ExecuteReader())
        {
            while (reader.Read())
            {
                // do something with the data
            }
        }
    }
}

注意：以上示例代码中的 OracleDbType.Varchar2 是 Oracle 数据库中的一种数据类型，如果你使用的是其他数据库，需要根据该数据库的数据类型来修改。另外，示例代码中的 SQL 语句都是简单的语句，如果你需要构建更复杂的 SQL 语句，需要使用更高级的技巧，比如使用存储过程、使用动态 SQL 等。