Tag:Data sheet

  • Memorandum of Common Database Command (Continuous Incremental Updates)


    Modify column names in tables alter table <tablename> change [column] <old column name> <new column name> <column definition> alter table test change name account varchar(30); How to get specific rows when querying data tables If you need to achieve the specific content of the first or last rows of the data table, you need to […]

  • Python batch deletes tens of millions of levels of MySQL data


    Scene description On-linemysqlThere is a table in the database with daily statistical results. There are more than 10 million items in the database every day. This is unexpected for us. How many statistical results are there? Operations and Maintenance Find, Disk Occupied200GFinally, we asked about the operation, we can only retain the last three days, […]

  • MySQL Connection Use


    In MySQL query, we can read data in one table by sorting, grouping, etc. This is relatively simple, but in real applications, we often need to read data from multiple tables. Next, I’ll introduce this method, link query join. INNER JOIN (Internal Connection, or Equivalent Connection): Gets records of field matching relationships in two tables. […]

  • Initial experience of MySQL / MariaDB


    It has been nine months since I applied for this blog number. I’d better deposit my knowledge here after thinking about it. But at first, like me, it’s still’I would like to use this article to witness the results’. If you are interested, you are also welcome to visit my CSDN blog. The following is […]

  • MySQL Added, Deleted and Amended Query Statements


    Create database: CREATE DATABASE database name; Create data table: CREATE TABLE table_name (column_name column_type); Insert data: INSERT INTO table_name         ( field1, field2,…fieldN )         VALUES          ( value1, value2,…valueN ); Note: If the inserted data is character type, single or double quotation marks must be used.   Delete database: DROP DATABASE < database name >; Delete […]

  • Views in SQL (Geek Time)


    view Views are virtual tables. They don’t have data. They’re a reddish concept in SQL. Figure 1 Views can help us use part of a table, not all tables. On the other hand, different query views can be formulated for different users. Create, update, and delete views View, as a virtual table, helps us encapsulate […]

  • SQL Server 2005 automatically creates data tables and automatically adds a field index


    The SQL statement for creating the data table is as follows: String tatlename = T_useruid; // Define a variable. Name for automatically creating data tables, current table name: T_useruid string sql = “CREATE TABLE [dbo].[” + tatlename + “]([Cid] [int] IDENTITY(1,1) NOT NULL,[Uid] [nchar](32) COLLATE Chinese_PRC_CI_AS NULL,CONSTRAINT [PK_” + tatlename + “] PRIMARY KEY CLUSTERED […]

  • 03. MySQL – Data Table Operation


    1. Creating data tables Basic grammar: create table table table table name (field name field type [field attribute], field name field type [field attribute],… ) [Table Options] Example: Creating data tables   The above error shows that tables must be placed in the corresponding database: there are two ways to upload tables to the designated […]

  • RBAC Privilege Management in PHP


    1. RBAC Concept and Principle RBAC: The full name is Role-Based Access Control. The Chinese translation is called role-based access control. Its main function is to realize the control of project authority. Effect: Different administrators can access different pages. For example, operators can only see the operation-related modules. Financial personnel can only see financial related […]

  • MySQL and Python Interaction in Database


    Preparing data Create data tables create database jing_dong charset=utf8; use jing_dong; create table goods( id int unsigned primary key auto_increment not null, name varchar(150) not null, cate_name varchar(40) not null, brand_name varchar(40) not null, price decimal(10,3) not null default 0, is_show bit not null default 1, is_saleoff bit not null default 0 ); insert data […]

  • PostgreSQL Tutorial (1): Data Table Explanation


    Definition of tables: For any relational database, tables are the core and basic object units of data storage. Now let’s start from here.  1. Create tables:   Copy codeThe code is as follows:     CREATE TABLE products (         product_no integer,         name text,         price numeric     );     2. Delete the table:   […]

  • SQLite Tutorial (3): Introduction to Datasheets and Views


    1. Create data tables: The command’s grammatical rules and usage are basically the same as most relational databases, so we also demonstrate the rules for creating tables in SQLite in an example way. But for some of the rules that are unique to SQLite, we will give additional instructions. Note: All of the following examples […]