For simplicity, we will reuse the student information table previously created under the database xiaohaizi_ Info and student transcript_ Score, you may have forgotten what these two tables look like. Let's review the structure of the two tables first:
Structure of students' basic information table
CREATE TABLE student_info (
number INT P ...
Posted on Thu, 11 Nov 2021 17:01:04 -0500 by hbalagh
The resource usage statistics of each sql statement in the database is often the most troublesome part and the most effective way to locate the problem. In addition, the resource usage can help the DBA to confirm whether the business concurrency increases, whether the hardware resources meet the existing requirements, and whether the parameters ...
Posted on Wed, 10 Nov 2021 20:32:21 -0500 by evanesq
The application scenario is - the data in the web page [must be in mysql] must be paged
-- Get the top in the table m Row data.
-- limit m
mysql> select * from s_emp limit 3;
-- limit m,n
-- m Represents a row subscript,Start from 0
-- n Represents the number of items displayed
-- Start on line 3,Display 5
Posted on Tue, 09 Nov 2021 22:17:56 -0500 by spags
creating a database in oracle is usually called creating a tablespace, and users of the tablespace need to be created
– create tablespaces
create tablespace jwxt datafile 'jwxt.ora' size 500m
autoextend on --Automatic extension
next 50m maxsize 20480m --Each automatic expansion 50 M，Up to 20480 M
Posted on Tue, 09 Nov 2021 20:05:11 -0500 by rhiza
Just understand - it's definitely not used in development
Single line function - string function, number function, date function
Multiline function (group function)
In fact, the database can be programmed
If you are using mysql8.x, you need to set it to allow custom functions
1. stay my.ini Add under file: log-bin ...
Posted on Tue, 09 Nov 2021 19:35:18 -0500 by adamhhh1
1, Performance_ Introduction to schema
schema: a diagram (table) that represents a plan or theory in the form of an outline or model.
MySQL's performance schema is used to monitor the resource consumption and resource waiting of MySQL server during a low-level operation.
1. It provides a method to che ...
Posted on Tue, 09 Nov 2021 04:41:20 -0500 by angeljyt
The main contents of this chapter are as follows:
1, Table constraint
in order to ensure that the database is inserted according to the specified rules, table constraints are introduced in the database. Common table constraints are 1. The primary key constraint primary key (cannot be empty or duplicate) if it is ...
Posted on Mon, 08 Nov 2021 20:56:54 -0500 by bubazoo
This article mainly introduces the use of MongoDB's bulkWrite() method by comparing batch and non batch operations. Incidentally, it is compared with relational database MySQL to compare the efficiency of these two different types of databases. If you just want to learn how to use bulkWrite(), just look at the first part.Test environment: win7 ...
Posted on Mon, 08 Nov 2021 17:13:00 -0500 by David4321
What connection query?
In the actual development, in most cases, the data is not queried from a single table. Generally, multiple tables are queried jointly to get the final result.
In actual development, a business usually corresponds to multiple tables. For example, students and classes have to save at least two tables. Of cour ...
Posted on Mon, 08 Nov 2021 00:39:19 -0500 by jengle52