如何使用Postgresql将值添加到2表中，然后使用Postgresql将外键从一个表映射到实体框架核心中的另一个表？

// 创建表A和表B的SQL语句
string createTableASql = "CREATE TABLE TableA (Id SERIAL PRIMARY KEY, ValueA VARCHAR(50));";
string createTableBSql = "CREATE TABLE TableB (Id SERIAL PRIMARY KEY, ValueB VARCHAR(50), ForeignKeyA INT REFERENCES TableA(Id));";

// 添加值到表A的SQL语句
string insertTableASql = "INSERT INTO TableA (ValueA) VALUES ('Value A');";

// 添加值到表B的SQL语句，并将外键映射到表A
string insertTableBSql = "INSERT INTO TableB (ValueB, ForeignKeyA) VALUES ('Value B', (SELECT Id FROM TableA WHERE ValueA = 'Value A'));";

// 查询表A和表B的SQL语句
string selectDataSql = "SELECT * FROM TableA;";
string selectRelatedDataSql = "SELECT * FROM TableB WHERE ForeignKeyA = (SELECT Id FROM TableA WHERE ValueA = 'Value A');";

// 执行SQL语句
using (var connection = new NpgsqlConnection(connectionString))
{
    connection.Open();

    // 创建表A和表B
    using (var command = new NpgsqlCommand(createTableASql, connection))
    {
        command.ExecuteNonQuery();
    }

    using (var command = new NpgsqlCommand(createTableBSql, connection))
    {
        command.ExecuteNonQuery();
    }

    // 添加值到表A
    using (var command = new NpgsqlCommand(insertTableASql, connection))
    {
        command.ExecuteNonQuery();
    }

    // 添加值到表B，并映射外键到表A
    using (var command = new NpgsqlCommand(insertTableBSql, connection))
    {
        command.ExecuteNonQuery();
    }

    // 查询表A的数据
    using (var command = new NpgsqlCommand(selectDataSql, connection))
    {
        using (var reader = command.ExecuteReader())
        {
            while (reader.Read())
            {
                // 处理表A的数据
            }
        }
    }

    // 查询关联的表B的数据
    using (var command = new NpgsqlCommand(selectRelatedDataSql, connection))
    {
        using (var reader = command.ExecuteReader())
        {
            while (reader.Read())
            {
                // 处理关联的表B的数据
            }
        }
    }
}