c# postgresql增删查改

在 C# 中操作 PostgreSQL 数据库，通常会使用 ADO.NET 或 Entity Framework 这样的 ORM (Object Relational Mapping) 框架。以下是一些基本的数据库操作步骤：

**连接到 PostgreSQL 数据库**:

using Npgsql;
string connectionString = "Host=localhost;Username=myuser;Password=mypassword;Database=mydatabase";
NpgsqlConnection connection = new NpgsqlConnection(connectionString);
connection.Open();

**插入数据 (Insert)**:

string sqlInsert = "INSERT INTO mytable (column1, column2) VALUES (@value1, @value2)";
NpgsqlCommand command = new NpgsqlCommand(sqlInsert, connection);
command.Parameters.AddWithValue("value1", value1);
command.Parameters.AddWithValue("value2", value2);
int rowsAffected = command.ExecuteNonQuery();

**查询数据 (Select)**:

string sqlQuery = "SELECT * FROM mytable WHERE condition";
NpgsqlCommand selectCommand = new NpgsqlCommand(sqlQuery, connection);
NpgsqlDataReader reader = selectCommand.ExecuteReader();
while(reader.Read())
{
   // 读取每一行数据
   string data1 = reader.GetString(0);
   int data2 = reader.GetInt32(1);
}
reader.Close();

**更新数据 (Update)**:

string sqlUpdate = "UPDATE mytable SET column1 = @newValue WHERE id = @id";
NpgsqlCommand updateCommand = new NpgsqlCommand(sqlUpdate, connection);
updateCommand.Parameters.AddWithValue("newValue", newValue);
updateCommand.Parameters.AddWithValue("id", id);
int rowsUpdated = updateCommand.ExecuteNonQuery();

**删除数据 (Delete)**:

string sqlDelete = "DELETE FROM mytable WHERE id = @id";
NpgsqlCommand deleteCommand = new NpgsqlCommand(sqlDelete, connection);
deleteCommand.Parameters.AddWithValue("id", id);
int rowsDeleted = deleteCommand.ExecuteNonQuery();

记得在每次操作完成后关闭连接和释放资源。