Programmer Group

Recently, I learned to write crawlers with Scrapy framework. In short, crawlers are to grab web pages from the Internet, parse web pages, and then store and analyze data, which will be transformed from web page analysis to data storage. The parsing technology used in the learning process, the use and advancement of each module of Scrapy to the ...

1. Stored procedure structure 1.1 First stored procedure create or replace procedure proc1( p_para1 varchar2, p_para2 out varchar2, p_para3 in out varchar2 )as v_name varchar2(20); begin v_name := 'Zhang Sanfeng'; p_para3 := v_name; dbms_output.put_line('p_pa ...

First Experience of SQL On Linux Note: Blog is timeliness. Content changes with updates. The time is May 22, 2017. The version of SQL On Linux will be officially released soon. This article has been installed and operated in common use. It feels good. Say less nonsense, please see. Installation: Installing SQL Services and Related Com ...

1. Batch Data Operation 1.1. Batch Generation Data 1.2. Batch insertion data 2. Batch generation script 3. Generating Data Dictionary 4. Common System Packages 4.1,DBMS_OUTPUT 4.2,DBMS_RANDOM 4.3. Other System Packages and Common Methods 5. Summary 1. Batch Data Operation 1.1. Batch Generation Data Generate integers between 1 and 5 SE ...

MySQL Learning Notes - Subqueries and Connections   Enter client into gbk encoding mode to display: mysql> SET NAMES gbk;   1. Subquery Definition of subqueries: Subquery refers to the SELECT clause that appears in other SQL statements. For example:   SELECT * FROM t1 WHERE col1 = (SELECT col2 FROM t2);   Where SELECT * FROM t1 is c ...

Summary: Labels PostgreSQL, PostGIS, box, grid, pointcloud, pgpointcloud, point aggregation, KNN, auto-driving, auto-distribution, scenes of science fiction movies with unmanned backgrounds are gradually changing from screen to reality with the development of technology. Label PostgreSQL, PostGIS, box, grid, pointcloud, pgpointcl ...

First, let's create a new temporary table for testing #country, which contains three fields: AreaNam, BelongTo, and Msg.Create table #country (AreaNam NVARCHAR(10),BelongTo Nvarchar(10),Msg varchar(100)) Let's insert a bunch of test data into this table: INSERT INTO #country SELECT 'China','China',null union all SELECT 'Jiangsu','China',null ...

Degraded dimension technology reduces the number of dimensions and simplifies the dimension data warehouse model. Simple schemas are easier to understand than complex ones and have better query performance.Sometimes, there is nothing in the dimension table except the business primary key. For example, in this sales order example, the order dime ...

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In actual enterprise usage scenarios, data, functions, computing resources in different projects may need to be used together. Then how to achieve this cross-project use, this paper uses practical examples to illustrate. Get ready Project space: grant_from, where authorized data, functions, and resources are in the project Project space: grant ...