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Hive sql programming interview questions Question 1 Table structure: uid,subject_id,score Ask: find out the students whose scores in all subjects are greater than the average score of a certain subject The data set is as follows 1001 01 90 1001 02 90 1001 03 90 1002 01 85 1002 02 85 1002 03 70 1003 01 70 1003 02 70 1003 03 85 1) Create t ...

The more you know, the more you don't know Friends who have used the Mybatis framework must have heard of PageHelper, a pagination artifact? In a simple sentence, PageHelper.startPage(pageNo,pageLimit) can help us realize paging! Did YYDS? No more nonsense, let's start exploring the mystery Daily use At present, many projects are based ...

Famous sayings and phrases "The easiest way to understand IQueryable is to think of it as a query that will produce a sequence of results when executed." - Jon Skeet What is the difference between LINQ to Object and LINQ to SQL? LINQ to SQL converts query expressions into SQL statements and executes them in the database. Instead of ...

Learning destination: PLSQL programming: Hello World, program structure, variables, process control, cursorStored procedure: concept, parameterless storage, parameterless storage (input, output)JAVA call stored procedure 1. PLSQL programming 1.1. Concept and purpose What is PL/SQL? PL/SQL(Procedure Language/SQL)PLSQL is a procedural ex ...

mysql login mysql -uroot -p password mysql -hip -uroot -p Password for connection target mysql --host=ip --user=root --password=Password for connection target MySQL exit exit quit DDL: operation database and table Create database create database Database name; Create a database, judge that it does not exist, a ...

1, Restraint· 1. Primary key constraint We can add constraints to a data table of a data table so that it can uniquely identify a data table. After being constrained, the data is not repeated and not unique: primary key mysql> use test; mysql> create table number( -> id int primary key, -> name varchar(20) -> ...

1 Introduction to MySQL database MySQL is a relational database. Due to its small size, fast speed, low total cost of ownership and open source, many small and medium-sized websites choose MySQL as the website database in order to reduce the total cost of ownership. Other advantages: it can be combined with other development languages, por ...

MyBatis if is similar to the if statement in Java. It is the most commonly used judgment statement in MyBatis. Using the if tag can save a lot of work in splicing SQL and focus on the maintenance of XML. The if statement is simple to use and is often used in combination with the test attribute. The syntax is as follows. When the judgment con ...

1. Special operation 1.1 fuzzy query Requirement: query the data containing "fine" in name, and arrange it in descending order by age @Test public void test9(){ SqlSession sqlSession = sqlSessionFactory.openSession(true); DemoUserMapper mapper = sqlSession.getMapper(DemoUserMapper.class); Map<String,O ...

I've been doing hive related work these days. Fortunately, I learned a little before and got started very quickly. Now I'm free, let's systematically review the syntax of hive sql again preface Hive is an application tool based on data warehouse. It is used to process structured data in Hadoop. It is based on Hadoop and operates the data th ...