Performance difference between NOT Exists and LEFT JOIN IN SQL Server -

-

I can have the following questions to check the existing records in the target table. 

  * Choose from table 1 where the column is not 1 (Select column 2 from Table 2) Select from Table 1 * Join table 2, where Table 1 Column 1 = Table 2. Column 2 Where Table 2 ID column is zero

I want to know which query has a better performance.

Go to not present generally.

This is in not in , if columns are tapable on both sides (and you have the desired words that you probably want)

left Join ... The tap sometimes combines with the latter filter to preserve the matching rows and can be very less efficient.

An example showing this is below no scheme and the plan to be excluded for being included in more than 1 million rows in the filter How to blow in.

does not exist

enter image details here

External participant ... NULL

Enter image details here < / P>

no

Enter image details here

< Pre> create table table 1 (IDCOLM INT identity primary key, column 1 ENTNLL, filler CHAR (8000) zero, unique (column 1, IDC column)); Table Table 2 (IDCOLM INT Identity Primary Key, Column 2 INT Zero, Filler CHAR (8000) Zero, Unique (Column 2, ID Column)); Include in Table 2 (column2). Include in column 1. In column 1 (column1) Master's selection number% 5 from Master ... Automatically select * from Table 1 T1 where not present (selection * from Table 2 T2 where T2. Column 2 = T 1. Column 1) SELECT * FROM Select Table 1 where the column 1 is not (Select Table 2 to Table 2) Table 1 * 1 of Table 1 Add Table 2 to Table 2. Column 1 = Table 2. Column 2 Where Table 2 IDCollum Null Drop Table Table 1, Table 2

Comments

Post a Comment

Popular posts from this blog

java - org.apache.http.ProtocolException: Target host is not specified -

-
I have written a simple httprequest / response code and I am getting this error below: I used to type in my classpath httpclient, httpcore, common -Codecs and general logging. I am very new to Java and I do not know what's going on here. Please help me. code: import org.apache.http.client.HttpClient; Import org.apache.http.client.methods.HttpGet; Import org.apache.http.HttpResponse; Import org.apache.http.impl.client.HttpClientBuilder; Import org.apache.http.Header; Import org.apache.http.HttpHeaders; Public class UnshorteningUrl {public static zero main (string [] args throws exception {HttpGet request = zero; HTTP Client Client = HTTP ClientBuilder.credit (). Build (); Try {Request = New HTTP Gate ("trib.me/1lBFzSi"); HttpResponse httpResponse = client.execute (request); Header [] header = httpResponse.getHeaders (HttpHeaders.LOCATION); // Preconditions.checkState (headers.length == 1); String new url = header [0] .getValue (); System.out.println ("new url...
Read more

java - Gradle dependencies: compile project by relative path -

-
Is it possible to specify a dependency on another gradeal project in the granular (in android studios) outside the current project limits? For example, with a relative path like this: dependence {collection project ('../../ stdlib / dagger'}} MyApp (path / user / foo / workspace / mypad) The app (Path / User / Foo / Workspace / MyPass / App) And I have an Android Library Project with 3 subdomules: stdlib (path is / user / foo / Utilities (Path / User / Foo / Workspace / Stadlib / Utilis) http (Path / User / Foo / Workspace / Stadlib / HT) / Li> What I have to do is compile the Dagger, Util, http module in the MyApp project. The Stidelib Library module under heavy development And MyApp will grow in the form of Growth, so I do not want to push them into a Mewen repository. I am a little change. is likely to add another Gredle projects in some way? I will push the study library into the Maven repository after the source is in search of a temp...
Read more

ruby on rails - Object doesn't support #inspect when used with .include -

-
So I have participated in a glitch error that I do not even know how to debug. I am very new to the railing, so it has kicked my ass well when I use the .includes (school) seen by the student, it gives a blue box error, But when I look at any other model and .includes (school) , the school works just fine. class student & lt; ActiveRecord :: Base has has_many: relationships, foreign_key: "liker_id", dependent :: has_many: matches, foreign_key: "student_1_id", dependent :: deleted belong_to: school belong_to: conference belong_to: would_you_rather belong_to: home city belong_to: year is_to: Major and class school & lt; on the console activatecord :: Affiliate for the base: conference includes: respondent, class: "school", foreign_key: "rival_id" (e.g. For: School) Select SQL generated Select "School". * "School" from "school" "ID" IN (1) error message back NoMethodError: u...
Read more