检索列表中每个 ID 的最新时间戳 - MySQL

Question

I'm running a command to retrieve all rows for today with IDs matching 1, 2, 3, etc.

I want to retrieve the latest entry for these IDs for today though.

So rather than getting:

BinID | Timestamp |

2 | 29/04/2021 3:49pm

2 | 29/04/2021 4:41pm

3 | 29/04/2021 2:24pm

I want:

BinID | Timestamp |

2 | 29/04/2021 4:41pm

3 | 29/04/2021 2:24pm

Is this possible?

This is the command I'm running at the moment.

MySqlCommand mysqlcom = new MySqlCommand("SELECT * FROM realtime_gpses WHERE BinId IN (" + binIdsCSVString + ") AND Timestamp >= CURDATE() AND Timestamp < CURDATE() + INTERVAL 1 DAY", mysqlcon);

where binIdsCSVString in this cases is just 2, 3.

Answer 1

You can try this

Select binid, max(timestamp) from table where ... Group by binid

As an alternative to in (1, 2...) you can generate:

where (binid = @binid1 or binid=@binid2.....)

You then add the parameters accordingly. All of this can be generated dynamically, yet it is parameterized.

See SQL select only rows with max value on a column to get row with max value.

and maybe even better: Retrieving the last record in each group - MySQL