ç®å½
1ãSQLè¯è¨çæ¦å¿µï¼
2ãsqlçåç±»
3ãDDLæä½ï¼æ°æ®å®ä¹è¯è¨
3.1ãæ°æ®åºæä½
å建æ°æ®åºï¼
éæ¯(å é¤)æ°æ®åºï¼
3.2ãæ°æ®ç±»åå表æä½
æ°æ®ç±»åï¼
å建表ï¼
ä¿®æ¹è¡¨ç»æï¼
4ãæ°æ®å®æ´æ§
4.1 å®ä½å®æ´æ§
主é®çº¦æ(primary key)
å¯ä¸çº¦æ(unique)
主é®èªå¢(auto_increment)
4.2 åå®æ´æ§
é空约æ(not null)
é»è®¤å¼(default)
4.3 å¼ç¨å®æ´æ§
å¤é®çº¦æ(foreign key)
5ãSQLè¿ç®ç¬¦ãåé æä½ç¬¦ï¼èµå¼æä½ç¬¦ï¼
5.1 ç®æ¯è¿ç®ç¬¦
5.2 æ¯è¾è¿ç®ç¬¦
5.3 é»è¾è¿ç®ç¬¦
5.4 ä½è¿ç®ç¬¦
5.5ãåé æä½ç¬¦ï¼èµå¼æä½ï¼
6ãDMLæä½ï¼æ°æ®æä½è¯è¨
6.1ãæå ¥æ°æ®insert into tablename(col1,col2...) values(val1,val2...)
6.2ãå¤å¶è¡¨ç»æåæ°æ®(å¤å¶è¡¨ç»æãå¤å¶è¡¨æ°æ®ãå¤å¶è¡¨ç»æ+æ°æ®)
6.3 ãä¿®æ¹æ°æ®update tablename set col1=val1,col2=val2... [where...]
6.4ãå é¤æ°æ®delete from tname [where...]
7ãDQLæä½ï¼æ°æ®æ¥è¯¢è¯è¨
8ãsqlå½æ°
1ãSQLè¯è¨çæ¦å¿µï¼
SQLæ¯ç»æåæ¥è¯¢è¯è¨(Structured Query Language),æ¯å ³ç³»åæ°æ®çä¸é¨éç¨è¯è¨,ç¨äºå®ç°å¯¹æ°æ®åºçæ¥è¯¢ï¼æ´æ°å管çã
2ãsqlçåç±»
- DDL(Data Definition Language),æ°æ®å®ä¹è¯è¨ï¼å®ç¨æ¥å®ä¹æ们çæ°æ®åºå¯¹è±¡ï¼å æ¬æ°æ®åºãæ°æ®è¡¨ååãéè¿ä½¿ç¨DDLï¼æ们å¯ä»¥createãdropãalteræ°æ®åºå表ç»æã
- DML(Data Manipulation Language),æ°æ®æä½è¯è¨ï¼æ们ç¨å®æä½åæ°æ®åºç¸å ³çè®°å½ï¼æ¯å¦Â insertãupdateãdeleteæ°æ®è¡¨ä¸çè®°å½ã
- DQL(Data Query Language),æ°æ®æ¥è¯¢è¯è¨ï¼æ们ç¨å®æ¥è¯¢æ³è¦çè®°å½ï¼selectï¼ã
- TCL(Transaction Control Language),äºå¡æ§å¶è¯è¨ï¼commit ã rollbackï¼ã
- DCL(Data Control Language),æ°æ®æ§å¶è¯è¨ï¼æ们ç¨å®æ¥å®ä¹è®¿é®æéåå®å ¨çº§å«ï¼grant ãrevokeï¼ã
3ãDDLæä½ï¼æ°æ®å®ä¹è¯è¨
SQLè¯å¥--mysqlå¢å æ¹æ¥è¯å¥ï¼å¢å æ°æ®åºãå®æ´æ§çº¦æãå建表ãä¿®æ¹è¡¨ç»æãæ¥ç表ãæå ¥æ°æ®ãä¿®æ¹æ°æ®ãå¤å¶è¡¨[æ°æ®åº]ãå é¤è¡¨[æ°æ®]ï¼ï¼https://blog.csdn.net/weixin_41685388/article/details/103107451
DDL(Data Definition Language),æ°æ®å®ä¹è¯è¨ï¼å®ç¨æ¥å®ä¹æ们çæ°æ®åºå¯¹è±¡ï¼å æ¬æ°æ®åºãæ°æ®è¡¨ååãéè¿ä½¿ç¨ DDLï¼æ们å¯ä»¥createãdropãalteræ°æ®åºå表ç»æã
è¯æ³ï¼
- â æ¯å¥ç»ææ è¯ç¬¦æ¯è±æåå·;
- â¡å¯¹å¤§å°åä¸ææï¼ä¸åºå大å°åï¼;
- â¢ç»æ°æ®åº,表çæ°æ®åºå¯¹è±¡èµ·ååæ¶ä¸è½ä½¿ç¨å ³é®å;
- â£æ³¨éç¨ï¼ #  ä¹å¯ä»¥ç¨ï¼Â -- ï¼--åé¢ä¸è¬ä¼å ä¸ä¸ªç©ºæ ¼ï¼;
- â¤èµ·åæ¶ä¸è½æ°åå¼å¤´ï¼ä¸è¬ç¨åæ¯æ°ååä¸å线.
3.1ãæ°æ®åºæä½
å建æ°æ®åºï¼
- create database [ if not exists ] dbname;
- create database if not exists abc default character set utf8;
- create database if not exists abc character set utf8;
éæ¯(å é¤)æ°æ®åºï¼
- drop database [if exists ] dbname;
3.2ãæ°æ®ç±»åå表æä½
æ°æ®ç±»åï¼
1)ãæ°å¼ç±»å    tinyint    1Byte=8bit  é常å°çæ´å()    smallint   2Byte  çæ´å    mediumint  3Byte  ä¸æ´å    int     4Byte     æ´å   è½æ¾åä½åè¿å¶æ°ï¼ææºå·å°±åä¸äºäºï¼    bigint    8Byte   é¿æ´å    float(n,m)   n代表é¿åº¦ï¼m代表å°æ°ç¹åä½æ°  4    double(n,m)   8    decimal(n,m)  å®ç¹æ°ï¼è¡¨ç¤ºéé±ï¼  æ´åçæ¯ä¸ç§é½åæ 符å·ï¼unsignedï¼åæ符å·ï¼signedï¼ä¸¤ç§ç±»åï¼floatådoubleæ»æ¯å¸¦ç¬¦å·çï¼ï¼å¨é»è®¤æ åµä¸å£°æçæ´ååéé½æ¯æ符å·çç±»åï¼charæç¹ç¹å«ï¼ï¼å¦æé声ææ 符å·ç±»åçè¯å°±éè¦å¨ç±»ååå ä¸unsigned ï¼å¦ï¼age tinyint unsigned,ï¼. |
2)ãæ¥æç±»å    date:æ¥æ    time:æ¶é´    datetime:æ¥ææ¶é´    timestamp:æ¶é´æ³    yearï¼å¹´ |
3)ã å符串类å    char(n):å®é¿å符串,n个åèï¼ä¸ä¸ªè±æåæ¯ä»£è¡¨1个åè    varchar(n):å¯åé¿å符串 ,n表示åæ¾çæå¤åèæ°ï¼æ¨è使ç¨Â |
4)ãÂ å ¶ä»ç±»å      binaryï¼å®é¿äºè¿å¶    varbinaryï¼å¯åé¿äºè¿å¶    blob:äºè¿å¶    text:大对象ï¼å符ï¼ææ¬ Â Â Â enum:æ举    set:éå   bit(1):ä¸ä¸ªåèï¼0/1ï¼ |
å建表ï¼
#``æ¯åè§ç¬¦å·ï¼å¯ä»¥ä¸è¦
create table `tablename` (
id int primary key auto_increment,
name varchar(20) not null,
hiredate date,
age tinyint unsigned,
sex bit(1)
)ENGINE=InnoDB character set utf8mb4;
#声æå段ï¼å段å称 å段类åï¼é¿åº¦ï¼ å段约ææ¡ä»¶ç...
desc tablename;  #æ¥ç表ç»æä¿¡æ¯
#å ä¸æ³¨è§£
CREATE TABLE `sc` (
`customer_id` BIGINT (20) NOT NULL COMMENT '客æ·ID',
`customer_name` VARCHAR (30) DEFAULT NULL COMMENT '客æ·å§å',
INDEX `idx_group_customer` (`customer_id`,`customer_name`) USING BTREE
) ENGINE = INNODB DEFAULT CHARSET = utf8mb4 COMMENT = '客æ·è¡¨';
ä¿®æ¹è¡¨ç»æï¼
alter table 表å rename/modify/change/add/drop/drop foreign key/engine = ******;
                          //ä¿®æ¹è¡¨ éå½å/ä¿®æ¹/æ´æ¹/æ·»å /å é¤/å é¤å¤é®/å¼æ
A.æ·»å å段
alter table tname add [column] col_name col_definition [after|first]
æ·»å å(é»è®¤æåä¸å)
alter table tname add colname colType
æ·»å å°æå®åå
alter table tname add colname2 colType after colname1
æ·»å å°é¦å
alter table tname add colname colType first;
B.ä¿®æ¹å段
alter table tname change/modify col_name new_col_name col_definition;
ä¿®æ¹å段å称
alter table tname change colname1 colname2 colType
ä¿®æ¹æ°æ®ç±»å
alter table tname change colname colname colType
alter table tname modify colname colType
ä¿®æ¹å段ä½ç½®
alter table tname modify colname colType after colname2;
C.å é¤å段
alter table tname drop colname;
D.éå½å
rename table tname to newname;
E.éå½å
alter table tname rename to newName;
F.æ¸
空表
truncate table tname;
G.å é¤æ´ä¸ªè¡¨
drop table tname;
4ãæ°æ®å®æ´æ§
æ°æ®å®æ´æ§æ代æ°æ®çåç¡®æ§åå¯é æ§
å®æ´æ§çº¦ææ¡ä»¶ï¼6个ï¼
primary keyï¼Â Â ä¸»é® ï¼å¯ä¸ä¸ä¸ºç©ºï¼ä¸ä¸ªè¡¨åªæä¸ä¸ªä¸»é®ï¼ |
auto_increment : èªå¢é¿ï¼å¿ 须为主é®åæ®µï¼ |
FOREIGN KEY :ãå¤é®Â  |
not null : é空 |
uniqueï¼ å¯ä¸  ï¼å¯ä»¥ä¸ºç©ºï¼ä¸ä¸ä¸ªè¡¨å¯ä»¥æå¤ä¸ªï¼ |
default : é»è®¤å¼ |
4.1 å®ä½å®æ´æ§
-
主é®çº¦æ(primary key)
-
主é®å段å¯ä¸ä¸ä¸è½ä¸ºç©º å建表æ¶å£°æä¸»é® create table user( userid int primary key, username varchar(20) );ENGINE= MYISAM character set utf8mb4; create table user( userid int, username varchar(20) character set utf8mb4, primary key(userid) ); ä¿®æ¹è¡¨ç»ææ·»å 约æ alter table user add CONSTRAINT PK_USERID primary key(userid); alter table user add primary key(userid); 1.æ¯å¼ è¡¨å¿ é¡»æä¸åªæä¸ä¸ªä¸»é® 2.å 许æèå主é®(å¤ä¸ªåæ®µå ±åç»å»ºä¸ºä¸ä¸ªä¸»é®) 3.å°½ééæ©éä¸å¡å段 éæ¯: alter table user drop primary key;
-
å¯ä¸çº¦æ(unique)
-
å¯ä¸ï¼å¯ä»¥ä¸ºç©ºï¼ä¸ä¸ä¸ªè¡¨å¯ä»¥æå¤ä¸ªï¼ å建表æ¶å£°æå¯ä¸çº¦æ create table user( userid int primary key, username varchar(20), card varchar(18) unique, ); create table user( userid int primary key, username varchar(20), card varchar(18), unique(card) ); ä¿®æ¹è¡¨ç»ææ·»å å¯ä¸çº¦æ alter table user add CONSTRAINT UN_CAED unique(card); alter table user add unique(card); éæ¯: drop unique index UN_CARD on user;
-
主é®èªå¢(auto_increment)
-
#èªå¢é¿ï¼å¿ 须为主é®å段ï¼ä¸ºæ°å¼åï¼æ·»å æ°æ®æ¶ä¸»é®èªè¡å¢å create table user( userid int primary key auto_increment, username varchar(20), card varchar(18) )character set utf8mb4;
4.2 åå®æ´æ§
ä¿è¯åçæ°æ®æ£ç¡®æ§
-
é空约æ(not null)
-
é»è®¤å¼(default)
4.3 å¼ç¨å®æ´æ§
ä¿è¯è¡¨ä¸å段å¼çææ
-
å¤é®çº¦æ(foreign key)
表ä¸å¤é®å段çåå¼éè¦ä¾èµäºå¦å¼ 表ç主é®çåå¼
create table example4 (
w_id int primary key auto_increment,
id int(11),
mame varchar(20) not null,
xuehao int(20) unique,
chengji int default 0,
constraint waj_4 foreign key (id) references example2 (id)
)engine=MYISAM character set utf8mb4;
#constraint å¤é®å foreign key (id) references ä»è¡¨ (主é®å段)
alter table emp add CONSTRAINT PK_DEPTNO foreign key(deptno) REFERENCES dept(deptno);
alter table emp drop foreign key;
5ãSQLè¿ç®ç¬¦ãåé æä½ç¬¦ï¼èµå¼æä½ç¬¦ï¼
5.1 ç®æ¯è¿ç®ç¬¦
select 2 + 2;
select 1 - 2;
select 3 * 4;
select 3 / 4; #0.75
select 3 / 0; #null
select 3 div 4; #æ´é¤
select 5 % 2; #åä½
5.2 æ¯è¾è¿ç®ç¬¦
#表达å¼ä¸ºçç»æ为1,å¦å为0
select 1 > 1;
select 1 < 1;
select 1 <> 1;
select 1 != 1;
is true,is not true,
is null,is not null,
between and,not between and,
in, not in
5.3 é»è¾è¿ç®ç¬¦
表达å¼ä¸ºçç»æ为1,å¦å为0
select 2 = 1 and 1 = 1;
select 1 = 1 or 1 = 2;
select !(2 <> 2);
5.4 ä½è¿ç®ç¬¦
#å
å°æ°æ®è½¬å为2è¿å¶ç¶å计ç®
select 1 & 0; #æä½ä¸
select 1 | 1; #æä½æ
select 1 ^ 2; #[çæ¡ï¼3]æä½å¼æï¼è½¬å为äºè¿å¶å对æ¯ï¼ç¸å为0ï¼ä¸ç¸å为1
select 1 ^ 3; #[çæ¡ï¼2]
5.5ãåé æä½ç¬¦ï¼èµå¼æä½ï¼
select @a,@b; #è¾åºç³æçaåéåbåéï¼é»è®¤å¼é½ä¸ºnull
select @a := 1,@b; #selectå½ä»¤èµå¼ç¨ := ç»ç³æçaåéèµå¼ï¼æ³¨æ := ä¸é´ä¸è½æç©ºæ ¼
set @b = 2; #setå½ä»¤ç»ç³æçåéèµå¼ç¨ =
select @a,@b; #æ¤æ¶è¾åºçç»æåºè¯¥ä¸º@a = 1 ,@b = 2, 两个åéé½å·²ç»è¢«èµå¼
select @a := "a" ,@b := 12.35; #声æçåéå¯ä»¥èµäºä»»æå¼ï¼æ´æ°ï¼å°æ°ï¼å符串ï¼...ï¼
#æ¡ä¾ ï¼æåº
set @rank = 0; #ç³æä¸ä¸ªrankåéï¼å¹¶èµäºåå§å¼0
-- 注éï¼æ¥è¯¢è¡¨emp,并æç
§salå段éåº,åæ¶è¾åº@rank := @rank + 1å段ï¼è¡¨ç¤ºç³æçåérankæ¯ä¸æ¬¡é½çäºä¸ä¸æ¬¡çç»æå 1ï¼
select *, @rank := @rank + 1 from emp
order by sal desc;
Â
6ãDMLæä½ï¼æ°æ®æä½è¯è¨
DML(Data Manipulation Language),æ°æ®æä½è¯è¨ï¼æ们ç¨å®æä½åæ°æ®åºç¸å ³çè®°å½ï¼æ¯å¦Â insertãupdateãdeleteæ°æ®è¡¨ä¸çè®°å½ãæ´æ¹æ°æ®ï¼ä¸æ¹åç»æãDMLæä½é½å¨äºç©çç¯å¢ä¸å®ç°ã
6.1ãæå ¥æ°æ®insert into tablename(col1,col2...) values(val1,val2...)
- å表ä¸ææå段添å æ°æ®
insert into tablename values(col1,col2,...) #valueå¼ç个æ°å顺åºå¿ é¡»å表ä¸å段ç个æ°å顺åºä¿æä¸è´
- å表ä¸é¨åå段添å æ°æ®
insert into tablename(col1,col2...) values(val1,val2...) #åææ¯ä¸æ·»å å¼çå段å 许为空ã #valueå¼å¾é¡ºåºå¿ é¡»ååé¢å段å称ç顺åºä¸è´
- æ¹éæ°æ®æå ¥
-
insert into tablename(col1,col2,...) values(val1_1,val2_1,...),(val1_2,val2_2,...),...
6.2ãå¤å¶è¡¨ç»æåæ°æ®(å¤å¶è¡¨ç»æãå¤å¶è¡¨æ°æ®ãå¤å¶è¡¨ç»æ+æ°æ®)
- sqlè¯å¥å¤å¶è¡¨ç»æåæ°æ®(å¤å¶è¡¨ç»æãå¤å¶è¡¨æ°æ®ãå¤å¶è¡¨ç»æ+æ°æ®)
1ãåæ¶å¤å¶è¡¨ç»æåæ°æ®å°æ°è¡¨ï¼æ°è¡¨ä¼å»é¤çº¦ææ¡ä»¶ï¼,å2次表æ¥è¯¢ä½¿ç¨æ¶å¸¸ç¨ CREATE TABLE æ°è¡¨ SELECT * FROM æ§è¡¨ 示ä¾ï¼ create table tablename3 select name,address,birthday,sex,phone,vocation from tablename2 where t2_id between 1 and 2; 2ãåªå¤å¶è¡¨ç»æå°æ°è¡¨ CREATE TABLE æ°è¡¨ SELECT * FROM æ§è¡¨ WHERE 1=2 æCREATE TABLE æ°è¡¨ LIKE æ§è¡¨ 示ä¾ï¼ create table tablename4 select * from tablename2 where 1=2; create table tablename5 like tablename2; 3ãå¤å¶æ§è¡¨çæ°æ®å°æ°è¡¨(å设两个表ç»æä¸æ ·) INSERT INTO æ°è¡¨ SELECT * FROM æ§è¡¨ 4ãå¤å¶æ§è¡¨çæ°æ®å°æ°è¡¨(å设两个表ç»æä¸ä¸æ ·) INSERT INTO æ°è¡¨(å段1,å段2,.......) SELECT å段1,å段2,...... FROM æ§è¡¨ 示ä¾ï¼ insert into tablename4 (name,address,birthday,sex,phone,vocation) select name,address,birthday,sex,phone,vocation from tablename2 where t2_id between 1 and 2; 5ãå¯ä»¥å°è¡¨1ç»æå¤å¶å°è¡¨2 SELECT * INTO 表2 FROM 表1 WHERE 1=2 6ãå¯ä»¥å°è¡¨1å å®¹å ¨é¨å¤å¶å°è¡¨2 SELECT * INTO 表2 FROM 表1 7ãshow create table æ§è¡¨; è¿æ ·ä¼å°æ§è¡¨çå建å½ä»¤ååºãæ们åªéè¦å°è¯¥å½ä»¤æ·è´åºæ¥ï¼æ´æ¹tableçååï¼å°±å¯ä»¥å»ºç«ä¸ä¸ªå®å ¨ä¸æ ·ç表 8ãmysqldump ç¨mysqldumpå°è¡¨dumpåºæ¥ï¼æ¹åååå导åå»æè ç´æ¥å¨å½ä»¤è¡ä¸è¿è¡ 9ãå¤å¶æ§æ°æ®åºå°æ°æ°æ®åºï¼å¤å¶å ¨é¨è¡¨ç»æ并ä¸å¤å¶å ¨é¨è¡¨æ°æ®ï¼ #mysql -u root -ppassword >CREATE DATABASE new_db; #mysqldump old_db -u root -ppassword--skip-extended-insert --add-drop-table | mysql new_db -u root -ppassword 10ã表ä¸å¨åä¸æ°æ®åºä¸ï¼å¦ï¼db1 table1, db2 table2) sql: insert into db1.table1 select * from db2.table2 (å®å ¨å¤å¶) insert into db1.table1 select distinct * from db2.table2(ä¸å¤å¶éå¤çºªå½ï¼ insert into tdb1.able1 select top 4 * from db2.table2 (ååæ¡çºªå½)
- å¨ç»ç«¯å¤å¶è¡¨å°æ°æ®åºï¼
-
å¨ç»ç«¯è¿è¡ï¼ mysql -h localhost -u root -p test(èªå·±çæ°æ®åºåï¼èªè¡æå®ï¼æ°æ®åºå¿ 须已åå¨) < C:\mysqldata\emp.sql(èªå·±çsqlæ件åæ¾ä½ç½®) --default-character-set=utf8 è¾å ¥mysqlçå¯ç å³å¯
- ç¨Navicat å¤å¶è¡¨ï¼
-- ç¨Navicat åæ°æ®åºå¤å¶
     Â
-- ç¨Navicat 跨æ°æ®åºå¤å¶
   Â
     Â
     Â
6.3 ãä¿®æ¹æ°æ®update tablename set col1=val1,col2=val2... [where...]
-
update tname set col1=val1,col2=val2... [where...] #å¦æupdate没æ使ç¨whereå代表对æ´å¼ 表ææè®°å½ä¿®æ¹,è°¨æ 使ç¨
6.4ãå é¤æ°æ®delete from tname [where...]
-
delete from tname [where...] #ä¸ä½¿ç¨whereå°å é¤æ´å¼ 表ä¸ææçè®°å½ -- delete,truncateådropçåºå«? -- deleteåªå é¤æ°æ®,ä¸ä¿®æ¹è¡¨ç»æ,ä¸éç½®èªå¢,éè¡å é¤ -- truncateæ¸ ç©ºè¡¨æ°æ®,ä¸ä¿®æ¹è¡¨ç»æ,éç½®èªå¢,å é¤é度æ¯deleteé« -- dropæ¸ ç©ºè¡¨ç»æ,表ç»ææ件åæ°æ®æä»¶å ¨é¨å é¤ æ¡ä¾ï¼ -- #å é¤(å é¤è¡¨ï¼å é¤è¡¨å段ï¼æ¡ä»¶å é¤è¡¨æ°æ®ï¼æ¸ 空表) -- #å é¤æ´ä¸ªè¡¨ -- drop table tablename5; -- #å é¤è¡¨å段 -- alter table tablename4 drop name; -- #æ¡ä»¶å é¤è¡¨æ°æ®(å½æ²¡æwhereéå¶æ¡ä»¶æ¶ï¼çä»·äºæ¸ 空表ï¼ä½æ¯èªå¢éå¶æ¡ä»¶ä¾ç¶ç»§ç»ï¼éè¡å é¤) -- delete from tablename4 where address = "å京å¸"; -- #æ¸ ç©ºè¡¨ï¼èªå¢æ¡ä»¶ä¹æ¸ 空被éç½®ï¼å ¨é¨æ°æ®ä¸èµ·å é¤ï¼æçæ´é«ï¼ -- truncate table tablename4;
7ãDQLæä½ï¼æ°æ®æ¥è¯¢è¯è¨
DQL(Data Query Language),æ°æ®æ¥è¯¢è¯è¨ï¼æ们ç¨å®æ¥è¯¢æ³è¦çè®°å½ï¼selectï¼ã
select cols #æ¥è¯¢å¹¶å±ç¤ºçæ°æ®(å段,表达å¼ç)
from tables #æ¥è¯¢çæ°æ®æ¥æº(表,ç»æé,è§å¾ç)
where condition #æ¡ä»¶è¯å¥
group by #åç»
having #åç»ä¹åçæ¡ä»¶å¤æ
order by #æåº(ascååº descéåº)
limit #éå¶ç»ææ¥è¯¢ï¼ä»
éäºmysqlï¼
SQLè¯è¨--mysqlåºç¡æ¥è¯¢è¯å¥ï¼å表æ¥è¯¢ãæ¡ä»¶æ¥è¯¢ãæ¥è¯¢å¹¶æåºãéå¶ç»ææ¥è¯¢ãæ¥è¯¢å¹¶æåãåç»èåæ¥è¯¢ã······ï¼ï¼https://blog.csdn.net/weixin_41685388/article/details/103186787
SQLè¯å¥--mysqlé«çº§æ¥è¯¢[å ³èæ¥è¯¢|å¤è¡¨æ¥è¯¢]ï¼è¿æ¥æ¥è¯¢ãåæ¥è¯¢ãèåæ¥è¯¢ãå¾è§£è¯´æå ç§å¸¸è§çè¿æ¥[èå]æ¥è¯¢ï¼:https://blog.csdn.net/weixin_41685388/article/details/103188974
8ãsqlå½æ°
SQLè¯å¥--mysql常ç¨å½æ°ï¼æµç¨å½æ°ãå符串å½æ°ãæ°å¦å½æ°ãæ¥æå½æ°ãèåå½æ°ãåç»å½æ°ãå å¯å½æ°ï¼ï¼https://blog.csdn.net/weixin_41685388/article/details/103186405
Â