{"id":105,"date":"2024-07-13T16:36:32","date_gmt":"2024-07-13T08:36:32","guid":{"rendered":"\/?p=105"},"modified":"2024-11-10T11:15:09","modified_gmt":"2024-11-10T03:15:09","slug":"mysql","status":"publish","type":"post","link":"\/?p=105","title":{"rendered":"Mysql"},"content":{"rendered":"\n

Mysql\u5b89\u88c5\uff1a<\/h3>\n\n\n\n

\u5b98\u65b9\u5b89\u88c5\uff1ahttps:\/\/dev.mysql.com\/downloads\/installer<\/a><\/p>\n\n\n\n

\u4e00\u8defNext\u3002<\/p>\n\n\n\n

Mysql\u7684\u542f\u52a8\u505c\u6b62\uff1a<\/h2>\n\n\n\n

Mysql\u542f\u52a8\/\u505c\u6b62<\/h4>\n\n\n\n
net start mysql80 \/\/\u542f\u52a8\nnet stop  mysql80 \/\/\u505c\u6b62<\/code><\/pre>\n\n\n\n
Mysql\u542f\u52a8\u5ba2\u6237\u7aef<\/h4>\n\n\n\n
Mysql [-h 127.0.0.1] [-P 3306] -u root -p\nMysql -u root -p<\/code><\/pre>\n\n\n\n
\n
\n
MySQL\u6570\u636e\u7c7b\u578b\uff1a<\/h2>\n\n\n\n
\u6570\u503c\u7c7b\u578b\uff1a<\/h3>\n\n\n\n
\u7c7b\u578b<\/td>\u5927\u5c0f<\/td>\u8303\u56f4\uff08\u6709\u7b26\u53f7\uff09<\/td>\u8303\u56f4\uff08\u65e0\u7b26\u53f7\uff09<\/td>\u7528\u9014<\/td><\/tr>
TINYINT<\/td>1 Bytes<\/td>
(-128\uff0c127)<\/td>		(0\uff0c255)<\/td>\u5c0f\u6574\u6570\u503c<\/td><\/tr>
SMALLINT<\/td>2 Bytes<\/td>
(-32 768\uff0c32 767)<\/td>		(0\uff0c65 535)<\/td>\u5927\u6574\u6570\u503c<\/td><\/tr>
MEDIUMINT<\/td>3 Bytes<\/td>
(-8 388 608\uff0c8 388 607)<\/td>
(0\uff0c16 777 215)<\/td>		\u5927\u6574\u6570\u503c<\/td><\/tr>
INT\u6216INTEGER<\/td>4 Bytes<\/td>(-2 147 483 648\uff0c2 147 483 647)<\/td>(0\uff0c4 294 967 295)<\/td>\u5927\u6574\u6570\u503c<\/td><\/tr>
BIGINT<\/td>8 Bytes<\/td>(-9,223,372,036,854,775,808\uff0c9 223 372 036 854 775 807)<\/td>(0\uff0c18 446 744 073 709 551 615)<\/td>\u6781\u5927\u6574\u6570\u503c<\/td><\/tr>
FLOAT<\/td>4 Bytes<\/td>(-3.402 823 466 E+38\uff0c-1.175 494 351 E-38)\uff0c0\uff0c(1.175 494 351 E-38\uff0c3.402 823 466 351 E+38)<\/td>0\uff0c(1.175 494 351 E-38\uff0c3.402 823 466 E+38)<\/td>\u5355\u7cbe\u5ea6
\u6d6e\u70b9\u6570\u503c<\/td><\/tr>
DOUBLE<\/td>8 Bytes<\/td>(-1.797 693 134 862 315 7 E+308\uff0c-2.225 073 858 507 201 4 E-308)\uff0c0\uff0c(2.225 073 858 507 201 4 E-308\uff0c1.797 693 134 862 315 7 E+308)<\/td>0\uff0c(2.225 073 858 507 201 4 E-308\uff0c1.797 693 134 862 315 7 E+308)<\/td>\u53cc\u7cbe\u5ea6
\u6d6e\u70b9\u6570\u503c<\/td><\/tr>
DECIMAL<\/td>\u5bf9DECIMAL(M,D) \uff0c\u5982\u679cM>D\uff0c\u4e3aM+2\u5426\u5219\u4e3aD+2<\/td>\u4f9d\u8d56\u4e8eM\u548cD\u7684\u503c<\/td>\u4f9d\u8d56\u4e8eM\u548cD\u7684\u503c<\/td>
\u5c0f\u6570\u503c<\/td><\/tr><\/tbody><\/table>
*\u6570\u636e\u6765\u6e90\u4e8e\u83dc\u9e1f\u6559\u7a0b<\/figcaption><\/figure>\n\n\n\n
\u65e5\u671f\u548c\u65f6\u95f4\u7c7b\u578b\uff1a<\/h3>\n\n\n\n
\u7c7b\u578b<\/td>\u5927\u5c0f
( bytes)               <\/td>		\u8303\u56f4<\/td>\u683c\u5f0f<\/td>\u7528\u9014<\/td><\/tr>
DATE<\/td>3<\/td>1000-01-01\/9999-12-31<\/td>
YYYY-MM-DD<\/td>		\u65e5\u671f\u503c<\/td><\/tr>
TIME<\/td>3<\/td>‘-838:59:59’\/’838:59:59’<\/td>
HH:MM:SS<\/td>		\u65f6\u95f4\u503c\u6216\u6301\u7eed\u65f6\u95f4<\/td><\/tr>
YEAR<\/td>1<\/td>1901\/2155<\/td>YYYY<\/td>\u5e74\u4efd\u503c<\/td><\/tr>
DATETIME<\/td>8<\/td>‘1000-01-01 00:00:00’ \u5230 ‘9999-12-31 23:59:59’<\/td>YYYY-MM-DD hh:mm:ss<\/td>\u6df7\u5408\u65e5\u671f\u548c\u65f6\u95f4\u503c<\/td><\/tr>
TIMESTAMP<\/td>4<\/td>‘1970-01-01 00:00:01’ UTC \u5230 ‘2038-01-19 03:14:07’ UTC
\u7ed3\u675f\u65f6\u95f4\u662f\u7b2c 2147483647<\/strong> \u79d2\uff0c\u5317\u4eac\u65f6\u95f4 2038-1-19 11:14:07<\/strong>\uff0c\u683c\u6797\u5c3c\u6cbb\u65f6\u95f4 2038\u5e741\u670819\u65e5 \u51cc\u6668 03:14:07<\/td>		YYYY-MM-DD hh:mm:ss<\/td>\u6df7\u5408\u65e5\u671f\u548c\u65f6\u95f4\u503c\uff0c\u65f6\u95f4\u6233<\/td><\/tr><\/tbody><\/table>
*\u6570\u636e\u6765\u6e90\u4e8e\u83dc\u9e1f\u6559\u7a0b<\/figcaption><\/figure>\n\n\n\n
\u5b57\u7b26\u4e32\u7c7b\u578b\uff1a<\/h3>\n\n\n\n
\u7c7b\u578b<\/td>\u5927\u5c0f<\/td>\u7528\u9014<\/td><\/tr>
CHAR<\/td>0-255 bytes<\/td>\u5b9a\u957f\u5b57\u7b26\u4e32<\/td><\/tr>
VARCHAR<\/td>0-65535 bytes<\/td>\u53d8\u957f\u5b57\u7b26\u4e32<\/td><\/tr>
TINYBLOB<\/td>0-255 bytes<\/td>\u4e0d\u8d85\u8fc7 255 \u4e2a\u5b57\u7b26\u7684\u4e8c\u8fdb\u5236\u5b57\u7b26\u4e32<\/td><\/tr>
TINYTEXT<\/td>0-255 bytes<\/td>\u77ed\u6587\u672c\u5b57\u7b26\u4e32<\/td><\/tr>
BLOB<\/td>0-65 535 bytes<\/td>\u4e8c\u8fdb\u5236\u5f62\u5f0f\u7684\u957f\u6587\u672c\u6570\u636e<\/td><\/tr>
TEXT<\/td>0-65 535 bytes<\/td>\u957f\u6587\u672c\u6570\u636e<\/td><\/tr>
MEDIUMBLOB<\/td>0-16 777 215 bytes<\/td>\u4e8c\u8fdb\u5236\u5f62\u5f0f\u7684\u4e2d\u7b49\u957f\u5ea6\u6587\u672c\u6570\u636e<\/td><\/tr>
MEDIUMTEXT<\/td>0-16 777 215 bytes<\/td>\u4e2d\u7b49\u957f\u5ea6\u6587\u672c\u6570\u636e<\/td><\/tr>
LONGBLOB<\/td>0-4 294 967 295 bytes<\/td>\u4e8c\u8fdb\u5236\u5f62\u5f0f\u7684\u6781\u5927\u6587\u672c\u6570\u636e<\/td><\/tr>
LONGTEXT<\/td>0-4 294 967 295 bytes<\/td>\u6781\u5927\u6587\u672c\u6570\u636e<\/td><\/tr><\/tbody><\/table>
*\u6570\u636e\u6765\u6e90\u4e8e\u83dc\u9e1f\u6559\u7a0b<\/figcaption><\/figure>\n<\/div>\n<\/div>\n\n\n\n
SQL\u57fa\u7840\u547d\u4ee4\uff1a<\/h1>\n\n\n\n
DDL:<\/h2>\n\n\n\n
DDL-\u6570\u636e\u5e93\u64cd\u4f5c\uff1a<\/h3>\n\n\n\n
\u67e5\u8be2\uff1a<\/h4>\n\n\n\n
\u67e5\u8be2\u6240\u6709\u6570\u636e\u5e93<\/p>\n\n\n\n
show databases; \/\/\u7ed3\u5c3e\u4e00\u5b9a\u8981\u52a0; \u548c \u7a7a\u683c\uff01\uff01<\/code><\/pre>\n\n\n\n
\u67e5\u8be2\u5f53\u524d\u6570\u636e\u5e93<\/p>\n\n\n\n
select databases(); <\/code><\/pre>\n\n\n\n
\u521b\u5efa\uff1a<\/h4>\n\n\n\n
create database if not exists \u6570\u636e\u540d [default charset utf8mb4\\utf8]; <\/code><\/pre>\n\n\n\n
\u5220\u9664\uff1a<\/h4>\n\n\n\n
drop database if exists \u6570\u636e\u540d; \ntruncate table \u8868\u540d; <\/code><\/pre>\n\n\n\n
\u4f7f\u7528:<\/h4>\n\n\n\n
use \u6570\u636e\u540d; <\/code><\/pre>\n\n\n\n
DDL-\u8868\u64cd\u4f5c:<\/h3>\n\n\n\n
\u521b\u5efa\uff1a<\/h4>\n\n\n\n
create table \u8868\u540d(\n    \u5b57\u6bb51 \u5b57\u6bb51\u6570\u636e\u7c7b\u578b [comment '\u6ce8\u91ca'],\n    \u5b57\u6bb52 \u5b57\u6bb52\u6570\u636e\u7c7b\u578b [comment '\u6ce8\u91ca'],\n    \u5b57\u6bb53 \u5b57\u6bb53\u6570\u636e\u7c7b\u578b [comment '\u6ce8\u91ca'],\n    \u5b57\u6bb54 \u5b57\u6bb54\u6570\u636e\u7c7b\u578b [comment '\u6ce8\u91ca']\n) [comment '\u6ce8\u91ca']; <\/code><\/pre>\n\n\n\n
\u65f6\u95f4\u9ed8\u8ba4\u503c\uff1a<\/h4>\n\n\n\n
AUTO_INCREMENT \/\/\u81ea\u52a8\u586b\u5199\u7f16\u53f7\nprimary key    \/\/\u53ea\u80fd\u6709\u4e00\u4e2a\u503c\nTIMESTAMP DEFAULT CURRENT_TIMESTAMP\n               \/\/\u81ea\u52a8\u586b\u5199\u65f6\u95f4\u6233\nDATE DEFAULT CURRENT_DATE   \"\u4ec5\u9002\u914d8.0.13\u4ee5\u4e0a\u7684mysql\u7248\u672c\"\n              \/\/\u9ed8\u8ba4\u503c\u8bbe\u7f6e\u5f53\u524d\u65f6\u95f4\n<\/code><\/pre>\n\n\n\n
\n
\u67e5\u8be2\uff1a<\/h4>\n<\/blockquote>\n\n\n\n
desc \u8868\u540d; <\/code><\/pre>\n\n\n\n
\u6dfb\u52a0\/\u4fee\u6539\u8868\u5185\u5bb9\uff1a<\/h4>\n\n\n\n
alter table \u8868\u540d add \u5b57\u6bb5 \u5b57\u6bb5\u6570\u636e\u7c7b\u578b [comment '\u6ce8\u91ca'];\n                 modify    \u4fee\u6539\u5b57\u6bb5\u7c7b\u578b   (\u8001\uff0c\u65b0)\n                 change    \u4fee\u6539\u5b57\u6bb5       (\u8001\uff0c\u65b0\uff0c\u65b0\u7684\u5b57\u6bb5\u7c7b\u578b)\n                 drop      \u5220\u9664\u5b57\u6bb5\n                 rename to \u4fee\u6539\u8868\u540d       (\u8001\uff0c\u65b0)<\/code><\/pre>\n\n\n\n
DDL\u603b\u7ed3\uff1a<\/h3>\n\n\n
\n
\"\"<\/div><\/figure><\/div>\n\n\n
\u53ef\u89c6\u5316Mysql\uff1a<\/h3>\n\n\n\n
\u7834\u89e3\u7248\uff1ahttps:\/\/www.cnblogs.com\/xiaohuhu\/p\/17218430.html<\/a><\/p>\n\n\n
\n
\"\"<\/div><\/figure><\/div>\n\n\n
DML<\/h2>\n\n\n\n
DML-\u4fee\u6539\u8868\u5185\u5bb9\u64cd\u4f5c\uff1a<\/h3>\n\n\n\n
\u6dfb\u52a0\uff1a<\/h4>\n\n\n\n
insert into \u8868\u5355(\u680f1,\u680f2,\u680f3,\u680f4...) values(\u5185\u5bb91,\u5185\u5bb92,\u5185\u5bb93,\u5185\u5bb94...); <\/code><\/pre>\n\n\n\n
\u4fee\u6539\uff1a<\/h4>\n\n\n\n
update \u8868\u5355 set \u4fee\u6539\u680f = '\u5185\u5bb9' where id = '\u4f4d\u7f6e'; <\/code><\/pre>\n\n\n\n
\u5220\u9664\uff1a<\/h4>\n\n\n\n
delete from \u8868\u5355 where id = '\u4f4d\u7f6e'; <\/code><\/pre>\n\n\n\n
DML\u5c0f\u7ed3\uff1a<\/h3>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
DQL<\/h2>\n\n\n\n
\u865a\u62df\u6570\u636e\u5b9e\u4f8b<\/h4>\n\n\n\n
create table s_user(\n    id int comment 'id',\n    workid int comment '\u5de5\u4f5cid',\n    name varchar(50) comment '\u59d3\u540d',\n    gender char(1) comment '\u6027\u522b',\n    idcard varchar(50) comment '\u8eab\u4efd\u8bc1',\n    dress varchar(50) comment '\u5730\u5740',\n    data date comment '\u65e5\u671f'\n);\n\nINSERT INTO s_user (id, workid, name, gender, idcard, dress, data) VALUES\n(1, 1001, '\u5f20\u4e09', 'M', '11010519800605371X', '\u5317\u4eac\u5e02\u671d\u9633\u533aXX\u8857\u9053XX\u53f7', '2023-04-01'),\n(2, 1002, '\u674e\u56db', 'F', '32032220000101002X', '\u6c5f\u82cf\u7701\u5f90\u5dde\u5e02XX\u533aXX\u8def', '2023-04-02'),\n(3, 1003, '\u738b\u4e94', 'M', '510104199012121234', '\u56db\u5ddd\u7701\u6210\u90fd\u5e02XX\u533aXX\u5df7', '2023-04-03'),\n(4, 1004, '\u8d75\u516d', 'F', '440306200503084567', '\u5e7f\u4e1c\u7701\u6df1\u5733\u5e02XX\u533aXX\u5927\u53a6', '2023-04-04'),\n(5, 1005, '\u5b59\u4e03', 'M', '220204197509200011', '\u5409\u6797\u7701\u5409\u6797\u5e02XX\u53bfXX\u6751', '2023-04-05'),\n(6, 1006, '\u5468\u516b', 'F', '610103201008150002', '\u9655\u897f\u7701\u897f\u5b89\u5e02XX\u533aXX\u8857', '2023-04-06'),\n(7, 1007, '\u5434\u4e5d', 'M', '340203198802150012', '\u5b89\u5fbd\u7701\u829c\u6e56\u5e02XX\u533aXX\u8def', '2023-04-07'),\n(8, 1008, '\u90d1\u5341', 'F', '130102199507077890', '\u6cb3\u5317\u7701\u77f3\u5bb6\u5e84\u5e02XX\u533aXX\u5c0f\u533a', '2023-04-08'),\n(9, 1009, '\u94b1\u5341\u4e00', 'M', '500236200204150001', '\u91cd\u5e86\u5e02\u5949\u8282\u53bfXX\u9547XX\u6751', '2023-04-09'),\n(10, 1010, '\u5173\u5341\u4e8c', 'F', '150102201203040003', '\u5185\u8499\u53e4\u81ea\u6cbb\u533a\u547c\u548c\u6d69\u7279\u5e02XX\u533aXX\u8857', '2023-04-10'),\n(11, 1011, '\u51af\u5341\u4e09', 'M', '210102197010010001', '\u8fbd\u5b81\u7701\u6c88\u9633\u5e02XX\u533aXX\u8def', '2023-04-11'),\n(12, 1012, '\u9648\u5341\u56db', 'F', '450103200806050004', '\u5e7f\u897f\u58ee\u65cf\u81ea\u6cbb\u533a\u5357\u5b81\u5e02XX\u533aXX\u8857', '2023-04-12'),\n(13, 1013, '\u536b\u5341\u4e94', 'M', '360102198501010005', '\u6c5f\u897f\u7701\u5357\u660c\u5e02XX\u533aXX\u8def', '2023-04-13'),\n(14, 1014, '\u848b\u5341\u516d', 'F', '654002201502140006', '\u65b0\u7586\u7ef4\u543e\u5c14\u81ea\u6cbb\u533a\u5854\u57ce\u5e02XX\u533aXX\u8def', '2023-04-14'),\n(15, 1015, '\u6c88\u5341\u4e03', 'M', '330106199207070007', '\u6d59\u6c5f\u7701\u676d\u5dde\u5e02XX\u533aXX\u8def', '2023-04-15'),\n(16, 1016, '\u97e9\u5341\u516b', 'F', '420106200109100008', '\u6e56\u5317\u7701\u6b66\u6c49\u5e02XX\u533aXX\u8857', '2023-04-16'),\n(17, 1017, '\u6768\u5341\u4e5d', 'M', '140222198311050009', '\u5c71\u897f\u7701\u5927\u540c\u5e02XX\u53bfXX\u4e61', '2023-04-17'),\n(18, 1018, '\u79e6\u4e8c\u5341', 'F', '530102200703080010', '\u4e91\u5357\u7701\u6606\u660e\u5e02XX\u533aXX\u8def', '2023-04-18'),\n(19, 1019, '\u4f55\u5eff\u4e00', 'M', '110108199702145678', '\u5317\u4eac\u5e02\u6d77\u6dc0\u533aXX\u8857\u9053XX\u53f7', '2023-04-19'),\n(20, 1020, '\u90ed\u5eff\u4e8c', 'F', '370202200301010011', '\u5c71\u4e1c\u7701\u9752\u5c9b\u5e02XX\u533aXX\u8def', '2023-04-20');<\/code><\/pre>\n\n\n\n
DQL\u57fa\u672c\u67e5\u8be2\u547d\u4ee4\uff1a<\/h4>\n\n\n\n
--\u67e5\u770b\u5c40\u90e8\nselect [name, gender, idcard] from s_user; \/\/[]\u4e2d\u4e3a\u7b5b\u9009\u540d\n--\u67e5\u770b\u5168\u90e8\nselect * from s_user;\n--\u521b\u5efa\u522b\u540d\nselect name '\u59d3\u540d' from s_user; \/\/\u522b\u540d\u53ef\u4ee5\u66f4\u597d\u65b9\u4fbf\u67e5\u770b\n--\u67e5\u770b\u5185\u5bb9(\u53bb\u9664\u91cd\u590d)\nselect distinct gender '\u6027\u522b' from s_user;<\/code><\/pre>\n\n\n\n
\u6761\u4ef6\u67e5\u8be2\uff1a<\/h4>\n\n\n\n
--\u67e5\u770b\u6761\u4ef6\u67e5\u8be2\u5185\u5bb9\nselect \u6240\u4ee5\u8868\u5355\u540d from s_user where \u67e5\u8be2\u6761\u4ef6; \n------------------------------------------------------------------\n-- \u5e74\u9f84\u7b49\u4e8e30\nselect * from employee where age = 30;\n-- \u5e74\u9f84\u5c0f\u4e8e30\nselect * from employee where age < 30;\n-- \u5c0f\u4e8e\u7b49\u4e8e\nselect * from employee where age <= 30;\n-- \u6ca1\u6709\u8eab\u4efd\u8bc1\nselect * from employee where idcard is null or idcard = '';\n-- \u6709\u8eab\u4efd\u8bc1\nselect * from employee where idcard;\nselect * from employee where idcard is not null;\n-- \u4e0d\u7b49\u4e8e\nselect * from employee where age != 30;\n-- \u5e74\u9f84\u572820\u523030\u4e4b\u95f4\nselect * from employee where age between 20 and 30;\nselect * from employee where age >= 20 and age <= 30;\n-- \u4e0b\u9762\u8bed\u53e5\u4e0d\u62a5\u9519\uff0c\u4f46\u67e5\u4e0d\u5230\u4efb\u4f55\u4fe1\u606f\nselect * from employee where age between 30 and 20;\n-- \u6027\u522b\u4e3a\u5973\u4e14\u5e74\u9f84\u5c0f\u4e8e30\nselect * from employee where age < 30 and gender = '\u5973';\n-- \u5e74\u9f84\u7b49\u4e8e25\u621630\u621635\nselect * from employee where age = 25 or age = 30 or age = 35;\nselect * from employee where age in (25, 30, 35);\n-- \u59d3\u540d\u4e3a\u4e24\u4e2a\u5b57\nselect * from employee where name like '__';\n-- \u8eab\u4efd\u8bc1\u6700\u540e\u4e3aX\nselect * from employee where idcard like '%X';<\/code><\/pre>\n\n\n\n
\u67e5\u8be2\u6761\u4ef6<\/h5>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
\u603b\u548c\u67e5\u8be2\uff08\u805a\u5408\u51fd\u6570\uff09\uff1a<\/h4>\n\n\n\n
select \u805a\u5408\u51fd\u6570 from s_user;\n-----------------------------------------\nselect count(name) from s_user;\/\/\u67e5\u8be2\u6240\u6709\u4eba\u6570<\/code><\/pre>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
\u5206\u7ec4\u6761\u4ef6\u67e5\u8be2\uff1a<\/h4>\n\n\n\n
select \u8868\u5355\u540d from [where \u6761\u4ef6\u67e5\u8be2] group by \u8868\u5355\u540d [having \u6761\u4ef6];\n----------------------------------------------------------------\n--\u67e5\u8be2\u6267\u884c\u4f18\u5148\u7ea7 \nwhere > \u805a\u5408\u51fd\u6570 > having <\/strong>\n----------------------------------------------------------------\n-- \u6839\u636e\u6027\u522b\u5206\u7ec4\uff0c\u7edf\u8ba1\u7537\u6027\u548c\u5973\u6027\u6570\u91cf\uff08\u53ea\u663e\u793a\u5206\u7ec4\u6570\u91cf\uff0c\u4e0d\u663e\u793a\u54ea\u4e2a\u662f\u7537\u54ea\u4e2a\u662f\u5973\uff09\nselect count(*) from employee group by gender;\n-- \u6839\u636e\u6027\u522b\u5206\u7ec4\uff0c\u7edf\u8ba1\u7537\u6027\u548c\u5973\u6027\u6570\u91cf\nselect gender, count(*) from employee group by gender;\n-- \u6839\u636e\u6027\u522b\u5206\u7ec4\uff0c\u7edf\u8ba1\u7537\u6027\u548c\u5973\u6027\u7684\u5e73\u5747\u5e74\u9f84\nselect gender, avg(age) from employee group by gender;\n-- \u5e74\u9f84\u5c0f\u4e8e45\uff0c\u5e76\u6839\u636e\u5de5\u4f5c\u5730\u5740\u5206\u7ec4\nselect workaddress, count(*) from employee where age < 45 group by workaddress;\n-- \u5e74\u9f84\u5c0f\u4e8e45\uff0c\u5e76\u6839\u636e\u5de5\u4f5c\u5730\u5740\u5206\u7ec4\uff0c\u83b7\u53d6\u5458\u5de5\u6570\u91cf\u5927\u4e8e\u7b49\u4e8e3\u7684\u5de5\u4f5c\u5730\u5740\nselect workaddress, count(*) address_count from employee where age < 45 group by workaddress having address_count >= 3;<\/code><\/pre>\n\n\n\n
\u6392\u5e8f\u67e5\u8be2\uff1a<\/h4>\n\n\n\n
select * from s_user order by<\/strong> data desc; \n-------------------------------------------------------------------\n\u5347\u5e8f: asc<\/strong>\n\u5012\u5e8f: desc<\/strong>\n-------------------------------------------------------------------\n-- \u6839\u636e\u5e74\u9f84\u5347\u5e8f\u6392\u5e8f\nSELECT * FROM employee ORDER BY age ASC;\nSELECT * FROM employee ORDER BY age;\n-- \u4e24\u5b57\u6bb5\u6392\u5e8f\uff0c\u6839\u636e\u5e74\u9f84\u5347\u5e8f\u6392\u5e8f\uff0c\u5165\u804c\u65f6\u95f4\u964d\u5e8f\u6392\u5e8f\nSELECT * FROM employee ORDER BY age ASC, entrydate DESC;\n\/\/\u5982\u679c\u662f\u591a\u5b57\u6bb5\u6392\u5e8f\uff0c\u5f53\u7b2c\u4e00\u4e2a\u5b57\u6bb5\u503c\u76f8\u540c\u65f6\uff0c\u624d\u4f1a\u6839\u636e\u7b2c\u4e8c\u4e2a\u5b57\u6bb5\u8fdb\u884c\u6392\u5e8f<\/code><\/pre>\n\n\n\n
\u5206\u9875\u67e5\u8be2\uff1a<\/h4>\n\n\n\n
select \u5b57\u6bb5\u5217\u8868 from \u8868\u540d limit \u8d77\u59cb\u7d22\u5f15, \u67e5\u8be2\u8bb0\u5f55\u6570;\n------------------------------------------------------\n-- \u67e5\u8be2\u7b2c\u4e00\u9875\u6570\u636e\uff0c\u5c55\u793a10\u6761\nSELECT * FROM employee LIMIT 0, 10;\n-- \u67e5\u8be2\u7b2c\u4e8c\u9875\nSELECT * FROM employee LIMIT 10, 10;\n------------------------------------------------------\nFROM -> WHERE -> GROUP BY -> SELECT -> ORDER BY -> LIMIT\n<\/code><\/pre>\n\n\n\n
DQL\u5c0f\u7ed3\uff1a<\/h4>\n\n\n\n
\"\"<\/div><\/figure>\n","protected":false},"excerpt":{"rendered":"
Mysql\u5b89\u88c5\uff1a \u5b98\u65b9\u5b89\u88c5\uff1ahttps:\/\/dev.mysql.com\/downloads\/installer […]<\/p>\n","protected":false},"author":1,"featured_media":255,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[14],"tags":[27],"class_list":["post-105","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-mysql","tag-mysql"],"_links":{"self":[{"href":"\/index.php?rest_route=\/wp\/v2\/posts\/105"}],"collection":[{"href":"\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=105"}],"version-history":[{"count":32,"href":"\/index.php?rest_route=\/wp\/v2\/posts\/105\/revisions"}],"predecessor-version":[{"id":262,"href":"\/index.php?rest_route=\/wp\/v2\/posts\/105\/revisions\/262"}],"wp:featuredmedia":[{"embeddable":true,"href":"\/index.php?rest_route=\/wp\/v2\/media\/255"}],"wp:attachment":[{"href":"\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=105"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=105"},{"taxonomy":"post_tag","embeddable":true,"href":"\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=105"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}