有什么方法可以从 SQLDatabase C# 检索一年中任何一个月的所有记录

Question

I have succeeded in getting all record of sales transaction for today on just clicking a button. Below is my codes

con.Open();
string query = "select Date Transactioncode, Productname, Total FROM Stock WHERE Date >= CAST(GETDATE() AS DATE) ORDER BY Date DESC";
SqlDataAdapter SDA = new SqlDataAdapter(query, con);
DataTable dt = new DataTable();
SDA.Fill(dt);
dataGridView1.DataSource = dt;
con.Close(); 

The problem I am having is how to get all sales transaction for the month or any month and year that i wish to search. I am using 2 comboBoxes to select month and year in order to get records from the SQLDatabase. Below the codes i had tried which kept producing error.

con.Open();
string query = "SELECT * FROM Stock WHERE Month(Date) = '"+comboMonth.Text+"' AND Year(Date) = '"+comboYear.Text+"'";
SqlDataAdapter SDA = new SqlDataAdapter(query, con);
DataTable dt = new DataTable();
SDA.Fill(dt);
dataGridView1.DataSource = dt;
con.Close();

this is the error i got: Conversion failed when converting the varchar value 'January' to data type int"

kindly help please

Answer 1

I would do this on the SQL side, as there are functions there to render date in any form, which you can compare to. It might not make for the most efficient query.

Either rendering the date as a string would allow use of 'like' and an index (I always liked the ISO YYYY-MM-DD HH:MM:SS.ssssss), or indexing the function expression is also allowed now.

For just one year one month, you should calculate the first and last second/day of date-times and do a range scan on the date-time value, which is both more efficient and non-hash (ordered) index friendly. Some Date types are of day granularity, some are date-time. https://docs.microsoft.com/en-us/sql/t-sql/functions/date-and-time-data-types-and-functions-transact-sql?view=sql-server-ver15 And of course the exact ends of days vary with Daylight Savings and the like, a real mess doing queries by shift on 3 shifts a day!