How to COUNT(*) in Slick 2.0?

问题:

According to the Slick 2.0 documentation, to get the count of rows in a table:

val q1 = coffees.length
// compiles to SQL (simplified):
//   select count(1) from "COFFEES"

However, it turns out that coffees.length is of type Column[Int].

How does one execute the query and get the value?

回答1:

I just had this same problem upgrading to slick 2.0. I forget where the exact method lives, but the generic .run seems to work for me, i.e.

coffees.length.run

回答2:

StaticQuery.queryNA[Int]("select count(*) from \"" + TableName + "\"").first

Quotes are needed if your table name is not upper case.

回答3:

Try coffees.length.first should execute and return Int

Sorry, indeed, in the slick 1.0 there was first method to do this, in Slick 2.0 they get rid of it in favor of more generic run.

The function to execute query is

coffees.length.run