如何在DataGridView中显示多个表中的数据

Question

Curriculum table
===
CurriculumID (PK, auto-increment)
CurriculumName Varchar(255)

GradeLevel table
===
GradeLevelID (PK, auto-increment)
GradeLevel Varchar(255)
CurriculumID (foreign key to Curriculum)

SubjectCreator table
===
SubjectID(PK, auto-increment)
SubjectName Varchar(255)
SubjectDescription Varchar(255)
GradeLevelID (foreign key to GradeLevel)

到目前为止，这些是我的代码，我不知道用来显示3个表的查询。仅尝试了2个表。这些是两个表的代码。string sql = "select GradeLevelID，GradeLevelName，CurriculumName from GradeLevelCreator inner join CurriculumCreator on GradeLevelCreator.CurriculumID = CurriculumCreator.CurriculumID"；

string connectionString = "Data Source=TOSHIBA-PC\\KENNETH;Initial Catalog=HSPAEnrollmentSystem;Integrated Security=True";
string sql = "";
SqlConnection connection = new SqlConnection(connectionString);
SqlDataAdapter dataadapter = new SqlDataAdapter(sql, connection);
DataSet ds = new DataSet();
connection.Open();
dataadapter.Fill(ds, "GradeLevelCreator");
connection.Close();
dataGridView1.DataSource = ds;
dataGridView1.DataMember = "GradeLevelCreator";

我想我只需要查询来显示多个或3个表。提前谢谢你！

Answer 1

查询时可以连接2个以上的表。

https://technet.microsoft.com/en-us/library/ms191430%28v=sql.105%29.aspx

Answer 2

尝试执行以下SQL语句：

SELECT s.SubjectID, s.SubjectName, s.SubjectDescription,
g.GradeLevel, c.CurriculumName FROM SubjectCreator s
INNER JOIN GradeLevel g ON s.GradeLevelID = g.GradeLevelID
INNER JOIN Curriculum c ON g.CurriculumID = c.CurriculumID