查詢表達式中缺少語法錯誤運算符

Question

當我運行以下查詢時，查詢表達式中出現語法錯誤。

private void button8_Click(object sender, EventArgs e)
{
    connection.Open();
    OleDbCommand command = new OleDbCommand();
    command.Connection = connection;
    string query1 = "UPDATE Points SET PNTS = 
                    (case when EmpName = '" + comboBox1.Text + 
                    "' then  '" + label15.Text + "' when EmpName = '" +
                    comboBox2.Text + "' then '" + label16.Text + 
                    "' when EmpName = '" + comboBox3.Text + "' then '" +
                    label17.Text + "' end) WHERE EmpName in ('" +
                    comboBox1.Text + "', '" + comboBox2.Text + "', '" +
                    comboBox3.Text + "')";

    command.CommandText = query1;
    command.ExecuteNonQuery();
    connection.Close();
}

錯誤是：

查詢表達式“（（當EmpName ='Sam'然后是5.6'，當EmpName ='shane'然后是'1.6'，當EmpName ='Mike'然后'0.8'結束時的情況））語法錯誤（缺少運算符）。

Answer 1

您的sql中有語法錯誤（ms Access不包含大小寫表達式）。 如下重寫源代碼行：

string query1 =
      "UPDATE Points SET PNTS = "
    + "SWITCH ("
        + "  EmpName = '" + comboBox1.Text + "', '" + label15.Text + "'"
        + ", EmpName = '" + comboBox2.Text + "', '" + label16.Text + "'"
        + ", EmpName = '" + comboBox3.Text + "', '" + label17.Text + "'"
        + ", true, ''"
    + ")"
    + " WHERE EmpName in ('" + comboBox1.Text + "', '" + comboBox2.Text + "', '" + comboBox3.Text + "')"
;

為了應對sql注入的風險，請考慮使用參數化的sql，因為一些注釋者建議：

OleDbParameter parameter;

// The n-th generic placeholder in the sql string will be set to the n-th registered Parameter Value.
// '12' represents the data size, adjustment may be needed ( can possibly be dropped altogether ) 
parameter = command.Parameters.Add("@InputParm", OleDbType.VarChar, 12);
parameter.Value = comboBox1.Text;
parameter = command.Parameters.Add("@InputParm", OleDbType.VarChar, 12);
parameter.Value = label15.Text;
parameter = command.Parameters.Add("@InputParm", OleDbType.VarChar, 12);
parameter.Value = comboBox2.Text;
parameter = command.Parameters.Add("@InputParm", OleDbType.VarChar, 12);
parameter.Value = label16.Text;
parameter = command.Parameters.Add("@InputParm", OleDbType.VarChar, 12);
parameter.Value = comboBox3.Text;
parameter = command.Parameters.Add("@InputParm", OleDbType.VarChar, 12);
parameter.Value = label17.Text;
parameter = command.Parameters.Add("@InputParm", OleDbType.VarChar, 12);
parameter.Value = comboBox1.Text;
parameter = command.Parameters.Add("@InputParm", OleDbType.VarChar, 12);
parameter.Value = comboBox2.Text;
parameter = command.Parameters.Add("@InputParm", OleDbType.VarChar, 12);
parameter.Value = comboBox3.Text;

string query1 =
      "UPDATE Points SET PNTS = "
    + "SWITCH ("
        + "  EmpName = ?, ?"
        + "  EmpName = ?, ?"
        + "  EmpName = ?, ?"
        + ", true, ''"
    + ")"
    + " WHERE EmpName in (?, ?, ?)"
;

警告

未經測試的代碼，源自文檔。

Answer 2

（如果EmpName ='Sam'然后是'5.6'.....）

您不必對數值使用引號。 數據庫中的“ PNTS”是字符串嗎？ 如果沒有，請嘗試刪除這些值的引號。