mysql脚本可以放在一个文件里(filename.sql)在mysql执行这个文件就OK
执行命令:/. 文件路径
create database mydata;
use mydata;
--mysql常用数据类型
int,double,char,varchar,datetime,longtext
创建表
use mydata;
create table dept
(
deptno int primary key,
dname varchar(14),
loc varchar(13)
);
create table emp
(
empno int primary key,
ename varchar(10),
job varchar(10),
mgr int,
hiredate datetime,
sal double,
comm double,
deptno int,
foreign key (deptno) references dept(deptno)
);
show databases;
show tables;
desc dept;
insert into dept values (10,'a','a');
insert into dept values (20,'b','b');
insert into dept values (30,'c','c');
insert into dept values (40,'d','d');
insert into dept values (50,'e','e');
commit;
--mysql 分页
select * from dept order by deptno desc limit 3,2;//从第三条往后数两条
--mysql 自增(auto_increment)
create table article
(
id int primary key auto_increment,
title varchar(255)
);
insert into article values (null,'a');
insert into article values (null,'b');
insert into article (title) values ('c');
--mysql 日期处理
select now();
select date_format(now(),'%y-%m-%d %h:%i:%s');
insert into emp values (9999,'test','clerk',7369,'1981-12-23 12:23:23',8000,80,10);

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MySQLstringtypesincludeVARCHAR,TEXT,CHAR,ENUM,andSET.1)VARCHARisversatileforvariable-lengthstringsuptoaspecifiedlimit.2)TEXTisidealforlargetextstoragewithoutadefinedlength.3)CHARisfixed-length,suitableforconsistentdatalikecodes.4)ENUMenforcesdatainte

MySQLoffersvariousstringdatatypes:1)CHARforfixed-lengthstrings,2)VARCHARforvariable-lengthtext,3)BINARYandVARBINARYforbinarydata,4)BLOBandTEXTforlargedata,and5)ENUMandSETforcontrolledinput.Eachtypehasspecificusesandperformancecharacteristics,sochoose

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ToaddusersinMySQLeffectivelyandsecurely,followthesesteps:1)UsetheCREATEUSERstatementtoaddanewuser,specifyingthehostandastrongpassword.2)GrantnecessaryprivilegesusingtheGRANTstatement,adheringtotheprincipleofleastprivilege.3)Implementsecuritymeasuresl

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The string data types in MySQL include CHAR, VARCHAR, BINARY, VARBINARY, BLOB, and TEXT. The collations determine the comparison and sorting of strings. 1.CHAR is suitable for fixed-length strings, VARCHAR is suitable for variable-length strings. 2.BINARY and VARBINARY are used for binary data, and BLOB and TEXT are used for large object data. 3. Sorting rules such as utf8mb4_unicode_ci ignores upper and lower case and is suitable for user names; utf8mb4_bin is case sensitive and is suitable for fields that require precise comparison.

The best MySQLVARCHAR column length selection should be based on data analysis, consider future growth, evaluate performance impacts, and character set requirements. 1) Analyze the data to determine typical lengths; 2) Reserve future expansion space; 3) Pay attention to the impact of large lengths on performance; 4) Consider the impact of character sets on storage. Through these steps, the efficiency and scalability of the database can be optimized.


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