变量名"@Loan_id"已经声明.变量名称在查询批处理或存储过程中必须唯一. [英] The variable name '@Loan_id' has already been declared. Variable names must be unique within a query batch or stored procedure.

问题描述

String query = "insert into Installments(Loan_id,Date,Amount)values(@Loan_id,@Date,@Amount)";
            SqlCommand cmd = new SqlCommand(query, cn);
            cmd.Prepare();

            for (i = 0; i < dataGridView1.Rows.Count; i++)
            {
                cmd.Parameters.AddWithValue("@Loan_id", txtloanidofinstallmentform.Text); 
                cmd.Parameters.AddWithValue("@Date", dataGridView1.Rows[i].Cells["Date"].Value);
                cmd.Parameters.AddWithValue("@Amount", dataGridView1.Rows[i].Cells["Amount"].Value);
            }

            cmd.ExecuteNonQuery();
            MessageBox.Show("record stored");




        }

添加了代码块[/编辑]

Code block added[/Edit]

推荐答案

您需要在循环内发出一件事的查询，并且每次都需要清除参数循环.

You need to issue the query inside the loop for one thing, and you need to clear the parameters each time round the loop.

String query = "insert into Installments(Loan_id,Date,Amount)values(@Loan_id,@Date,@Amount)";
SqlCommand cmd = new SqlCommand(query, cn);
cmd.Prepare();

for (i = 0; i < dataGridView1.Rows.Count; i++)
    {
    cmd.Parameters.Clear();
    cmd.Parameters.AddWithValue("@Loan_id", txtloanidofinstallmentform.Text);
    cmd.Parameters.AddWithValue("@Date", dataGridView1.Rows[i].Cells["Date"].Value);
    cmd.Parameters.AddWithValue("@Amount", dataGridView1.Rows[i].Cells["Amount"].Value);
    cmd.ExecuteNonQuery();
    }

MessageBox.Show("record stored");

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