JDBC connection mode and steps
1. Register driver
Diver dirver =new com.mysql.jdbc.Diver(); In this way, the interface of Sun company is implemented first. mysql manufacturers implement it according to the interface. Dirver on the left is the interface, and interface implementation classes on the right DiverManager.registerDirver(dirver); ...
Posted by wxflint on Sat, 23 Oct 2021 07:33:34 -0700
Title: submit sql script file with flynk sql client Date: twenty 21-10-22 22:11:34 Tag: [Flink, SQL client] Category: flink
We know that sql-client.sh can provide us with an SQL interactive interface, so that we can see the execution results or interactive query table results without executing an SQL.
In fact, we can also submit sql scripts t ...
Posted by Drannon on Fri, 22 Oct 2021 07:39:30 -0700
Hi Wen Ledao's large TV series "when is davinci updated" finally came to an end in the early autumn of 21 years, followed by the official release of the popular new product datart (Digital Art). This year, we can see that there are many such people in the group
And so on..
Posted by xXx_Hobbes_xXx on Fri, 22 Oct 2021 00:16:58 -0700
MySQL advanced - Notes - 01
Video of this article: Dark horse MySQL advanced
1, MySQL architecture
1-1 overview of MySQL architecture
The entire MySQL Server consists of the following components:
Connection Pool: Connection Pool componentManagement services & Utilities: management services and tools componentsSQL interface: SQL i ...
Posted by GoncaloF on Wed, 20 Oct 2021 23:07:31 -0700
1, Operation database: CRUD
C (Create): Create
create database Database name; Create a database. When it is judged that it does not exist, create it again:
create datsbase if not exists Database name; Create the database and specify the character set:
create database Database name character set ...
Posted by hank9481 on Wed, 20 Oct 2021 22:00:14 -0700
All query statements must be; End with a semicolon
Display database show databases;
Use database use database_name;
Table showing the database show tables;
Display column information of database table show columns from table_name;
Retrieve data SELECT
-- Retrieve all data from multiple columns ...
Posted by rushdot on Tue, 19 Oct 2021 11:59:48 -0700
1. Insert data INSERT INTO
1.1 insert complete line
INSERT INTO customers
This example inserts a new customer into the customers table. Each column of data stored in the table is given by VALUES, and each column must be provided with a value. If a column has no value, NULL is u ...
Posted by Rick Corbett on Sun, 17 Oct 2021 11:21:42 -0700
mysql8.0 official website: processing group by
1. Initial conditions
Now there is a table with two pairs of name = pants
Execute the following sql to get the data grouped by name: GROUP BY name
SELECT name,author,SUM(price) FROM `t_book`
GROUP BY name
1055 exception occurred while executing sql
SELECT name,author,SUM ...
Posted by bpops on Sat, 16 Oct 2021 10:01:08 -0700
1) What is a federated index?
A federated index refers to indexing multiple columns in a table. In other words, multiple columns on the table add up to form an index for fast query.
2) How do I use federated indexes?
First, add an index to the table Add to table when creating table:
CREATE TABLE t(
Posted by Bit343 on Fri, 15 Oct 2021 14:42:37 -0700