• Dynamic splicing expression


    Will we encounter the following query requirements in the project? For example, you need to find members that meet the following conditions:  Condition group 1: male members aged 30-40 Condition group 2: female members aged 20-30 Condition group 3: members aged 60-80 with Unknown Gender There are and relationships within condition groups, but there are […]

  • Springboot integration spring data mongodb operation mongodb details


    quote:www.mydlq.club/article/85/ 1、 Introduction to mongodb Mongodb is a product between relational database and non relational database. It has the richest functions among non relational databases and is most similar to that of relational database. The data structure it supports is very loose. It is a JSON like bson format, so it can store more complex […]

  • JS beware of empty array trap


    Today, when I was writing code, I accidentally thought of trying the judgment condition of empty array. My requirement is that when the user enters the page for the first time, the “XXX” part displays “please enter the user name” to remind the user to enter some values I know I now have an array […]

  • Conditional types of typescript


    preface The official documents of typescript have long been updated, but the Chinese documents I can find are still in the older version. Therefore, some newly added and revised chapters are translated and sorted out. This article is compiled from “typescript Handbook”Conditional Types“Chapter. This article is not translated strictly according to the original text, and […]

  • Typescript official manual translation plan [9]: type manipulation – condition type


    explain: at present, there is no Chinese translation of the latest official documents of typescript on the Internet, so there is such a translation plan. Because I am also a beginner of typescript, I can’t guarantee the 100% accuracy of translation. If there are errors, please point them out in the comment area; Translation content: […]

  • Delete the current row in the loop


     LOOP AT IT_035ALV INTO DATA(LS_035).        IF LS_035-ANZFB NE ‘OA approved’.*          DELETE  IT_035ALV INDEX sy-tabix.*          DELETE  IT_ 035ALV FROM LS_ 035. “Delete current workspace”          DELETE  IT_035ALV . Best practice of “delete current workspace” – delete the condition row. It is recommended to copy it to another table and do not delete it in recycling        ENDIF.      ENDLOOP.

  • oracle sql


    View Oracle database version Any of the following commands select * from v$version; select version from v$instance; Select version FROM Product_component_version Where SUBSTR(PRODUCT,1,6)=’Oracle’;   1.dual The smallest worksheet provided by Oracle has only one row and one column, which has some special functionsDual is a pseudo table because it does not store dataWhen we don’t […]

  • Improve the ES search module, query es like query database, with complete small cases


    Some time ago, the writing requirements were written into the search module. With more and more conditions, the combination of various conditions became more and more complex, and it was difficult to maintain in the later stage. Therefore, the previous search writing method was improved. I wrote a small case in my spare time to […]

  • Python basic loop


    Python has two ways to loop While loop. When the condition is true, cycle forever. If the condition is false, jump out of the cycle or not.Syntax: While condition: When you execute the following code, the program will always print Hello world. That’s because the condition a < B holds. a = 1 b = […]

  • Wan Da #20, how to filter data in index push down


    The original content of greatsql community cannot be used without authorization. Please contact Xiaobian and indicate the source for reprint. Experimental environment GreatSQL 8.0.25 InnoDB 1. Introduction to index push down 1. Index condition pushdown is short for ICP. 2.MySQL5. Version 6 introduces the function for optimizing queries. 3. Under some specific index conditions, ICP […]

  • Similarities and differences between Oracle and MySQL indexes in processing null fields


    ORACLE: SQL> create table tab2(c1 number, c2 number, c3 varchar2(10)); The table is made into a table. SQL> declare a number; begin a := 1; for i in 1 .. 500 loop for j in 1 .. 1000 loop insert into tab2 values(a,j,’a’); commit; a := a+1; end loop; end loop; end; / PL / […]

  • [little knowledge] querywrapper loop or condition


    background The project uses mybatis plus, which needs to traverse a grid of arraysorAssociation, but other conditions outside the array areand, similar select 1 from t where a = 1 and (b like ‘%2’ or b = ‘%3’ or b = ‘%4’) solution queryWrapper.and(qw -> { for (int i = 0; i < values.length; i++) […]