SQL Server - Join only when the condition is number












0















I have a table EmployeeLeave



  CREATE TABLE EmployeeLeave (

  EmployeeId INT,

  LeaveType VARCHAR()

  );


LeaveType can have numbers as well as string. 



  CREATE TABLE MST_LeaveReason (

  ReasonId INT,

  Reason VARCHAR()

  );



  SELECT * FROM EmployeeLeave EL

  LEFT JOIN MST_LeaveReason LR ON LR.ReasonId = EL.LeaveType


Above query will not work as LeaveType is not always number. I want this join to work only if the LeaveType is number. How can i implement it. Please help.



Thanks in advance.






sql sql-server join







share|improve this question























  • If your varchar is only going to have a length of 1, why not use char(1) and save the overhead of having a "variable" length?

    – Larnu
    Nov 22 '18 at 11:48













  • @Larnu: VARCHAR() is (fortunately?) not legal syntax. It's probably not shorthand for VARCHAR-with-no-length-which-is-implicitly-1 in this case.

    – Jeroen Mostert
    Nov 22 '18 at 11:51


















0















I have a table EmployeeLeave



  CREATE TABLE EmployeeLeave (

  EmployeeId INT,

  LeaveType VARCHAR()

  );


LeaveType can have numbers as well as string. 



  CREATE TABLE MST_LeaveReason (

  ReasonId INT,

  Reason VARCHAR()

  );



  SELECT * FROM EmployeeLeave EL

  LEFT JOIN MST_LeaveReason LR ON LR.ReasonId = EL.LeaveType


Above query will not work as LeaveType is not always number. I want this join to work only if the LeaveType is number. How can i implement it. Please help.



Thanks in advance.






sql sql-server join







share|improve this question























  • If your varchar is only going to have a length of 1, why not use char(1) and save the overhead of having a "variable" length?

    – Larnu
    Nov 22 '18 at 11:48













  • @Larnu: VARCHAR() is (fortunately?) not legal syntax. It's probably not shorthand for VARCHAR-with-no-length-which-is-implicitly-1 in this case.

    – Jeroen Mostert
    Nov 22 '18 at 11:51
















0












0








0








I have a table EmployeeLeave



  CREATE TABLE EmployeeLeave (

  EmployeeId INT,

  LeaveType VARCHAR()

  );


LeaveType can have numbers as well as string. 



  CREATE TABLE MST_LeaveReason (

  ReasonId INT,

  Reason VARCHAR()

  );



  SELECT * FROM EmployeeLeave EL

  LEFT JOIN MST_LeaveReason LR ON LR.ReasonId = EL.LeaveType


Above query will not work as LeaveType is not always number. I want this join to work only if the LeaveType is number. How can i implement it. Please help.



Thanks in advance.






sql sql-server join







share|improve this question














I have a table EmployeeLeave



  CREATE TABLE EmployeeLeave (

  EmployeeId INT,

  LeaveType VARCHAR()

  );


LeaveType can have numbers as well as string. 



  CREATE TABLE MST_LeaveReason (

  ReasonId INT,

  Reason VARCHAR()

  );



  SELECT * FROM EmployeeLeave EL

  LEFT JOIN MST_LeaveReason LR ON LR.ReasonId = EL.LeaveType


Above query will not work as LeaveType is not always number. I want this join to work only if the LeaveType is number. How can i implement it. Please help.



Thanks in advance.






sql sql-server join




sql sql-server join






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 22 '18 at 11:46









ErmaErma

104313




104313













  • If your varchar is only going to have a length of 1, why not use char(1) and save the overhead of having a "variable" length?

    – Larnu
    Nov 22 '18 at 11:48













  • @Larnu: VARCHAR() is (fortunately?) not legal syntax. It's probably not shorthand for VARCHAR-with-no-length-which-is-implicitly-1 in this case.

    – Jeroen Mostert
    Nov 22 '18 at 11:51





















  • If your varchar is only going to have a length of 1, why not use char(1) and save the overhead of having a "variable" length?

    – Larnu
    Nov 22 '18 at 11:48













  • @Larnu: VARCHAR() is (fortunately?) not legal syntax. It's probably not shorthand for VARCHAR-with-no-length-which-is-implicitly-1 in this case.

    – Jeroen Mostert
    Nov 22 '18 at 11:51



















If your varchar is only going to have a length of 1, why not use char(1) and save the overhead of having a "variable" length?

– Larnu
Nov 22 '18 at 11:48







If your varchar is only going to have a length of 1, why not use char(1) and save the overhead of having a "variable" length?

– Larnu
Nov 22 '18 at 11:48















@Larnu: VARCHAR() is (fortunately?) not legal syntax. It's probably not shorthand for VARCHAR-with-no-length-which-is-implicitly-1 in this case.

– Jeroen Mostert
Nov 22 '18 at 11:51







@Larnu: VARCHAR() is (fortunately?) not legal syntax. It's probably not shorthand for VARCHAR-with-no-length-which-is-implicitly-1 in this case.

– Jeroen Mostert
Nov 22 '18 at 11:51














1 Answer
1






active

oldest

votes


















3














Use try_convert():



SELECT *

FROM EmployeeLeave EL LEFT JOIN

     MST_LeaveReason LR

     ON LR.ReasonId = TRY_CONVERT(INT, EL.LeaveType);


You can also do this in the other direction:



SELECT *

FROM EmployeeLeave EL LEFT JOIN

     MST_LeaveReason LR

     ON CONVERT(VARCHAR(255), LR.ReasonId) = EL.LeaveType;


Then, work on fixing the data model. JOIN keys should be of the same type. Such conversions have a drastic affect on performance.






share|improve this answer























    Your Answer






    StackExchange.ifUsing("editor", function () {
    StackExchange.using("externalEditor", function () {
    StackExchange.using("snippets", function () {
    StackExchange.snippets.init();
    });
    });
    }, "code-snippets");

    StackExchange.ready(function() {
    var channelOptions = {
    tags: "".split(" "),
    id: "1"
    };
    initTagRenderer("".split(" "), "".split(" "), channelOptions);

    StackExchange.using("externalEditor", function() {
    // Have to fire editor after snippets, if snippets enabled
    if (StackExchange.settings.snippets.snippetsEnabled) {
    StackExchange.using("snippets", function() {
    createEditor();
    });
    }
    else {
    createEditor();
    }
    });

    function createEditor() {
    StackExchange.prepareEditor({
    heartbeatType: 'answer',
    autoActivateHeartbeat: false,
    convertImagesToLinks: true,
    noModals: true,
    showLowRepImageUploadWarning: true,
    reputationToPostImages: 10,
    bindNavPrevention: true,
    postfix: "",
    imageUploader: {
    brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
    contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
    allowUrls: true
    },
    onDemand: true,
    discardSelector: ".discard-answer"
    ,immediatelyShowMarkdownHelp:true
    });


    }
    });














    draft saved

    draft discarded


















    StackExchange.ready(
    function () {
    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53430313%2fsql-server-join-only-when-the-condition-is-number%23new-answer', 'question_page');
    }
    );

    Post as a guest















    Required, but never shown

























    1 Answer
    1






    active

    oldest

    votes








    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    3














    Use try_convert():



    SELECT *
    
FROM EmployeeLeave EL LEFT JOIN
    
     MST_LeaveReason LR
    
     ON LR.ReasonId = TRY_CONVERT(INT, EL.LeaveType);


    You can also do this in the other direction:



    SELECT *
    
FROM EmployeeLeave EL LEFT JOIN
    
     MST_LeaveReason LR
    
     ON CONVERT(VARCHAR(255), LR.ReasonId) = EL.LeaveType;


    Then, work on fixing the data model. JOIN keys should be of the same type. Such conversions have a drastic affect on performance.






    share|improve this answer




























      3














      Use try_convert():



      SELECT *
      
FROM EmployeeLeave EL LEFT JOIN
      
     MST_LeaveReason LR
      
     ON LR.ReasonId = TRY_CONVERT(INT, EL.LeaveType);


      You can also do this in the other direction:



      SELECT *
      
FROM EmployeeLeave EL LEFT JOIN
      
     MST_LeaveReason LR
      
     ON CONVERT(VARCHAR(255), LR.ReasonId) = EL.LeaveType;


      Then, work on fixing the data model. JOIN keys should be of the same type. Such conversions have a drastic affect on performance.






      share|improve this answer


























        3












        3








        3







        Use try_convert():



        SELECT *
        
FROM EmployeeLeave EL LEFT JOIN
        
     MST_LeaveReason LR
        
     ON LR.ReasonId = TRY_CONVERT(INT, EL.LeaveType);


        You can also do this in the other direction:



        SELECT *
        
FROM EmployeeLeave EL LEFT JOIN
        
     MST_LeaveReason LR
        
     ON CONVERT(VARCHAR(255), LR.ReasonId) = EL.LeaveType;


        Then, work on fixing the data model. JOIN keys should be of the same type. Such conversions have a drastic affect on performance.






        share|improve this answer













        Use try_convert():



        SELECT *
        
FROM EmployeeLeave EL LEFT JOIN
        
     MST_LeaveReason LR
        
     ON LR.ReasonId = TRY_CONVERT(INT, EL.LeaveType);


        You can also do this in the other direction:



        SELECT *
        
FROM EmployeeLeave EL LEFT JOIN
        
     MST_LeaveReason LR
        
     ON CONVERT(VARCHAR(255), LR.ReasonId) = EL.LeaveType;


        Then, work on fixing the data model. JOIN keys should be of the same type. Such conversions have a drastic affect on performance.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Nov 22 '18 at 11:48









        Gordon LinoffGordon Linoff

        781k35310414




        781k35310414
































            draft saved

            draft discarded




















































            Thanks for contributing an answer to Stack Overflow!


            • Please be sure to answer the question. Provide details and share your research!

            But avoid …



            • Asking for help, clarification, or responding to other answers.

            • Making statements based on opinion; back them up with references or personal experience.


            To learn more, see our tips on writing great answers.




            draft saved


            draft discarded














            StackExchange.ready(
            function () {
            StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53430313%2fsql-server-join-only-when-the-condition-is-number%23new-answer', 'question_page');
            }
            );

            Post as a guest















            Required, but never shown





















































            Required, but never shown














            Required, but never shown












            Required, but never shown







            Required, but never shown

































            Required, but never shown














            Required, but never shown












            Required, but never shown







            Required, but never shown







            Popular posts from this blog

            'app-layout' is not a known element: how to share Component with different Modules

            Image
            0 My application was working fine until I decided to go with lazy loading: So, my shared component looks like this: import { Component, Renderer2 } from '@angular/core'; export interface FormModel { captcha?: string; } @Component({ selector: 'app-layout', templateUrl: './app-layout.component.html', styleUrls: ['./app-layout.css'] }) export class FullLayoutComponent { } app-layout.component.ts I am using this component in my Another component say school-home.component.html like this: <app-layout> </app-layout> and it was working fine until I created a Module school-home.module.ts like this: import { NgModule } from '@angular/core'; import { CommonModule } from '@angular/common'; import { SchoolhomeRoutingModule ...
            Read more

            android studio warns about leanback feature tag usage required on manifest while using Unity exported app?

            Image
            .everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty{ height:90px;width:728px;box-sizing:border-box; } 0 This is a simple project showing cubes on Unity, exported to android project and imported on Android studio. On maifest file it showed following warning: Expecting <uses-feature android:name="android.software.leanback" android:required="false" /> tag I have no information about it. And also on default emptyview android project does not use/mention this feature. I know it is required by TV's and such but why its not added by default? Why is this? And Should I concern about it? android unity3d ...
            Read more

            WPF add header to Image with URL pettitions [duplicate]

            Image
            up vote 0 down vote favorite This question already has an answer here: Image source URI requiring authorization 3 answers Add header to all* HTTP requests on a machine 1 answer first of all sorry for my english. Recently I added some security in the backend of my project, and now I need to send a validation code(apiKey) inside the headers to retrieve the images. I have a problem with ALL images in my project that I had attached in my UI. For example, before I had: <Image Height="90" Source="{Binding Video.Thumbnail}"/> Now I need to change my code to create a CUSTOM petition add the apiKey in the header:...
            Read more