I have the following SQL
SELECT Tag , COUNT(*) , MAX(CreatedDate)
FROM dbo.tblTags
GROUP BY Tag
Which outputs the following:
+-----------------+------------------+-------------------------+
| Tag | (No column name) | (No column name) |
+-----------------+------------------+-------------------------+
| a great tag | 1 | 2015-04-01 18:30:31.623 |
| not a test | 1 | 2015-04-01 17:46:09.360 |
| test | 5 | 2015-04-01 18:13:17.920 |
| test2 | 1 | 2013-03-07 16:53:54.217 |
+-----------------+------------------+-------------------------+
I'm trying to replicate the output of that query using EntityFramework.
I have the following logic which works:
var GroupedTags = Tags.GroupBy(c => c.Tag)
.Select(g => new
{
name = g.Key,
count = g.Count(),
date = g.OrderByDescending(gt => gt.CreatedDate).FirstOrDefault().CreatedDate
})
.OrderBy(c => c.name);
But takes horribly long to execute compared to the raw SQL query. Any suggestions on how to optimise my approach? It somehow feels wrong.
If you want a max, use the Max()
Linq method:
var GroupedTags = Tags.GroupBy(c => c.Tag)
.Select(g => new
{
name = g.Key,
count = g.Count(),
date = g.Max(x => x.CreatedDate)
})
.OrderBy(c => c.name);
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