SQL 在 oledb 中查询（插入），在 VB.NET 中没有重复项

Question

我想要 oledb 中的 SQL 查询命令（插入）而不重复，有没有最好的推荐？

谢谢杰克

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Try
            connectionString = cn
            con = New OleDbConnection(connectionString)
            con.Open()
            Dim sql As String = "INSERT INTO EXAMPLE2 SELECT * FROM EXAMPLE1"
            cmd = New OleDbCommand(sql, con)
            cmd.ExecuteNonQuery()
            MessageBox.Show("Successfully Updated...", "Update")
            con.Close()
            Me.fillDataGridView1()
            Me.fillDataGridView2()
        Catch myerror As OleDbException
            MessageBox.Show("Error: " & myerror.Message)
        Finally
        End Try
    End Sub

Answer 1

要仅插入 EXAMPLE1 中不存在于 EXAMPLE2 中的行，您需要比较不想重复的行中每一列的值。

INSERT INTO EXAMPLE2 SELECT * FROM EXAMPLE1 EX1
WHERE NOT EXISTS
(SELECT * FROM EXAMPLE2 EX2 WHERE 
EX2.CODE = EX1.CODE AND
EX2.NOD = EX1.NOD AND
EX2.QTY = EX1.QTY AND
EX2.PRICE = EX1.PRICE AND
EX2.REMARK = EX1.REMARK
)

Answer 2

我根据下面的 link 得到了答案解决方案 (Avoid duplicates in INSERT INTO SELECT query in SQL Server)

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Try
            connectionString = cn
            con = New OleDbConnection(connectionString)
            con.Open()
            Dim sql As String = "INSERT INTO EXAMPLE2 (CODE,NOD,QTY,PRICE) SELECT t1.CODE, t1.NOD,t1.QTY, t1.PRICE FROM EXAMPLE1 t1 WHERE NOT EXISTS(SELECT CODE FROM EXAMPLE2 t2 WHERE t2.CODE = t1.CODE)"
            cmd = New OleDbCommand(sql, con)
            cmd.ExecuteNonQuery()
            MessageBox.Show("Successfully Updated...", "Update")
            con.Close()
            Me.fillDataGridView1()
            Me.fillDataGridView2()
        Catch myerror As OleDbException
            MessageBox.Show("Error: " & myerror.Message)
        Finally
        End Try
    End Sub

SQL 在 oledb 中查询（插入），在 VB.NET 中没有重复项

SQL query (insert into) in oledb without duplicates in VB.NET

sql

vb.net

oledb

oledbcommand

sql-insert