1.創(chuàng)建數(shù)據(jù)表：
(1)顯示當下所有數(shù)據(jù)庫：SHOW DATABASES；
(2)創(chuàng)建數(shù)據(jù)庫：CREATE DATABASE name;
(3)使用數(shù)據(jù)庫：USE test;
(4)查看當前打開的數(shù)據(jù)庫：SELECT DATABASE();
(5)創(chuàng)建數(shù)據(jù)表:
CREATE TABLE tb1(
username ,VARCHAR(20),
age TINYINT UNSIGNED,
salary FLOAT(8,2) UNSIGNED
);
(6)顯示數(shù)據(jù)表：SHOW TABLES;
(顯示當下數(shù)據(jù)庫下的數(shù)據(jù)表)
(7)顯示所有數(shù)據(jù)庫下的數(shù)據(jù)表：SHOW TABLES FROM mysql;
(8)查看數(shù)據(jù)表結(jié)構(gòu)：SHOW COLUMNS FROM tb1;
(9)往數(shù)據(jù)表中插入記錄：
INSERT tablename VALUES('TOM',25,7863.25);
INSET tb1(username,salary) VALUES('JOHN',45)；
給某幾個列賦值；
(此處當前插入了兩條在數(shù)據(jù)表中)
(10)查看數(shù)據(jù)表：
SELECT *FROM ?tb1;
(11)指定數(shù)據(jù)表數(shù)據(jù)非空：
NULL 字段值可以為空
NOT NULL 字段值禁止為空
CREATE TABLE tb2(
username VARCHAR(20) ?NOT NULL,
age TINYINT UNSIGNED NULL
);
SHOW COLUMNS FROM tb2;
INSET ?tb2 VALUES('TOM',NULL);
SELECT *FROM tb2;
INSET tb2 VALUES(NULL,NULL);
