对于许多值，SQL Server IN子句的等效速度更快

Question

I'm using OrmLite .NET with SQL Server 12.0. I want to select entities where a certain integer column (not the primary key) has one of many values, which I have in an array. An OrmLite expression like this:

q => query.Where(r => myIntegers.Contains(r.TheColumn))

gets translated to

WHERE "TheColumn" IN (1, 2, 3, ...) -- my integers

This works fine with ~100, but times out with 1000. How do I achieve the same effect with a larger list? Can I pass an array to SQL Server somehow or a table parameter?

Answer 1

Similar to what @JoeTaras commented, you can put the acceptable values into a subquery, something like;

SELECT TheColumn from TheTable T
INNER JOIN (SELECT * from (VALUES(1),(2),(3),(4)) as V1(value)) V
ON T.TheColumn = V.value

Answer 2

In OrmLite you may build raw SQL query you need (for example, from @Sam cd answer) and pass it to db.Select method:

string joinedIds = string.Join("),(", new List<int> {1, 2, 9});

string command =
    $"SELECT * from Employee AS E INNER JOIN (SELECT * from (VALUES( {joinedIds} )) as TV(value)) V ON E.Id = V.value";

List<Employee> employers = db.Select<Employee>(command);

Answer 3

I ended up using a temporary table for this, ie:

CREATE TABLE #ParamTempTable (Id BIGINT NOT NULL PRIMARY KEY);

INSERT INTO #ParamTempTable (Id) VALUES ((1), (2), (3));

SELECT *
FROM MyTable
WHERE Id IN (SELECT * FROM #ParamTempTable);

DROP TABLE #ParamTempTable;

I do this only when I have > 1000 values, otherwise I just use SQL IN (1, 2, 3) .

To implement this on OrmLite I had to subclass SqlServerExpression<T> and override VisitStaticArrayMethodCall and VisitEnumerableMethodCall to change how it handled Contains expressions. This class stores the commands to create and drop the temp tables separately and I have to run separate a SqlCommand for each of those. ( CREATE TABLE doesn't work in SqlCommand.ExecuteReader , unfortunately.) So this ended up being quite complicated, but it does work and is transparent to the caller. An added benefit is that I could eliminate duplicate parameters, so eg for o => ids.Contains(o.FromId) || ids.Contains(o.ToId) o => ids.Contains(o.FromId) || ids.Contains(o.ToId) the list ids gets sent to SQL server only once.