Catalog

WHERE

LIKE Operator instance

NOT keyword  

IN The operator  

 AND & OR Operator  

AND Operator

 OR Operator

AND & OR 

ORDER BY 

ORDER BY Multiple columns

SQL BETWEEN The operator  

SQL sentence

WHERE

WHERE Clause to filter records （ Finally get the specified content ）

Be careful ：

SQL Use single quotes around the text value （ Most database systems also accept double quotes ）.

In the previous example 'CN' The text field uses single quotation marks .

If it is a numeric field , Please don't use quotation marks .

LIKE Operator instance

LIKE The operator is used in WHERE Search for the specified pattern in the column .

NOT keyword  

IN The operator  

 AND & OR Operator  

AND Operator

 OR Operator

Below SQL Statements from "Websites" The countries selected in the table are "USA" perhaps "CN" All of our customers  

AND & OR 

Below SQL Statements from "Websites" Select in the table alexa Ranking higher than "15" And the country is "CN" or "USA" All websites of

ORDER BY 

ORDER BY By default, the keyword sorts the records in ascending order . If you need to sort records in descending order , You can use DESC keyword .

Below SQL Statements from "Websites" Select all sites in the table , And in accordance with the "alexa" Column sorting

Below SQL Statements from "Websites" Select all sites in the table , And in accordance with the "alexa" Sort columns in descending order  

ORDER BY Multiple columns

SELECT * FROM Websites

ORDER BY country,alexa; 

SQL BETWEEN The operator  

Below SQL Sentence selection alexa Be situated between 1 and 20 Between all websites

SELECT * FROM Websites
WHERE alexa BETWEEN 1 AND 20;

Below SQL Sentence selection alexa Be situated between 1 and 20 But country Not for USA and IND All websites of

SELECT * FROM Websites
WHERE (alexa BETWEEN 1 AND 20)
AND country NOT IN ('USA', 'IND');

SQL sentence

Mysql -uroot -p  enter   password   # Get into mysql Commands for managing the command line 

create database test1222; # Create database 

show databases; # Display all current databases 

drop database if exists test122202; # Delete database test122202, If the database exists 

drop table table_name;  # Delete a table ;
​
show tables;  # Display all data tables in the current library ;
​
desc student;  # Look at the data sheet student All fields in ;
​
alter table student add company varchar(50); # by student Add a field to the table ;