MySQL Basic Learning_Lesson 016_Simple Query Statement

1. The grammatical format of the query statement

Syntax format:

select 字段名1,字段名2,字段名3,... from 表名;

note:

(1) any of a SQL statement in English semicolon " ; " at the end

(2) SQL statements are not case sensitive

 

2. Examples of query statements

Create a new students data table

CREATE TABLE students(
    id INT NOT NULL PRIMARY KEY,
    name VARCHAR(255) NOT NULL,
    score INT(10),
    class VARCHAR(255)
);

Insert the following data into the newly created students data table

INSERT INTO students VALUES
(1,'张小明',82,1),
(2,'李翠花',75,3),
(3,'王强平',90,4),
(4,'赵宝强',65,3),
(5,'邹华文',88,2),
(6,'杨坤华',98,1),
(7,'刘海明',56,4),
(8,'赵德明',45,2),
(9,'张嘉玲',100,3),
(10,'金亚蓉',79,2),
(11,'刘伟强',NULL,1),
(12,'柯炳超',0,3),
(13,'习明',59,2),
(14,'周_学',62,3);

The created students data table is shown in the figure below

Example 1: Query student's grades?

SELECT name,score FROM students;

Example 2: Query the result of multiplying all student scores by 10

SELECT name,score*10 FROM students;