create database estore;
create database estore character set 'utf8mb4';

drop database estore;

alter database estore character set 'utf8mb4';

show databases;查看所有數(shù)據(jù)庫名
show create database estore;查看庫編碼

use estore;切換數(shù)據(jù)庫
select database();-- 查詢當(dāng)前使用的數(shù)據(jù)庫名稱

CREATE TABLE `t_user ` (
? `id` varchar(22) NOT NULL,
? `openid` varchar(50) NOT NULL COMMENT '微信opedid',
? `name` varchar(50) DEFAULT NULL COMMENT '用戶名稱',
? `phone` varchar(20) NOT NULL COMMENT '手機(jī)號碼',
? `province_code` varchar(10) DEFAULT NULL COMMENT '省份代碼',
? `city_code` varchar(10) DEFAULT NULL COMMENT '城市代碼',
? `county_code` varchar(10) DEFAULT NULL COMMENT '區(qū)縣代碼',
? `card_type` varchar(5) DEFAULT NULL COMMENT '證件類型',
? `id_card` varchar(30) DEFAULT NULL COMMENT '身份證',
? `region` varchar(10) DEFAULT NULL COMMENT '地區(qū)',
? `user_id` varchar(22) DEFAULT '0' COMMENT '普通用戶表id',
? `is_homeowner` varchar(2) DEFAULT NULL COMMENT '是否有房',
? `insurance_code` varchar(10) DEFAULT NULL COMMENT '所屬保險公司code',
? `promo_code` varchar(50) DEFAULT NULL COMMENT '推廣碼',
? `create_time` datetime DEFAULT NULL,
? `create_user` varchar(22) DEFAULT NULL,
? `update_time` datetime DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP,
? `update_user` varchar(22) DEFAULT NULL,
? `delete_flag` varchar(2) DEFAULT NULL COMMENT '刪除標(biāo)識 1是 0 否',

? PRIMARY KEY (`id`) USING BTREE,
? UNIQUE KEY `uniq_phone` (`phone`) USING BTREE COMMENT '微信用戶手機(jī)號，唯一索引',
? KEY `index_open_id` (`openid`) USING BTREE COMMENT 'opid普通索引，用于靜默登錄等'
) COMMENT '信息員表';

DROP TABLE t_user ;

-- 改表名
rename table t_user to t_user_info;
-- 改編碼集
alter table t_user character set 'utf8mb4';
-- 改存儲引擎
alter table applicationdesk ENGINE = InnoDB;

-- 查選中數(shù)據(jù)庫的所有表名
show tables;
-- 查表結(jié)構(gòu)(表中所有字段)
desc t_user;
show columns from t_user;-- 展示表的列詳情
-- 查建表信息
show create table t_user;
show create table t_mdm_employee \G;
-- 查詢所有表及其注釋
SELECT TABLE_NAME,TABLE_COMMENT FROM information_schema.TABLES WHERE table_schema='estore' ORDER BY table_name;
-- 查詢庫中所有字段及其相關(guān)屬性，如注釋等
select table_name,column_name,column_type,column_comment from information_schema.columns where table_schema='custom_sd';

-- 刪除索引
DROP INDEX uniq_phone ON t_sd_messenger_info;

-- 新增字段(默認(rèn)在最后一列追加)
ALTER TABLE t_user ADD name varchar(22) ?DEFAULT NULL COMMENT '用戶名稱' ;
-- 在age字段后面添加sex字段：
alter table t_user ?add sex tinyint not null COMMENT '用戶性別' after age ;
-- 在第一列添加sex字段
alter table t_user ?add sex tinyint not null first;　　

alter table t_user ?drop name;

-- 修改字段名?
alter table t_user change address address_level varchar(2) ?DEFAULT NULL COMMENT '地區(qū)級別' ;?
-- 修改屬性
alter table t_user modify name varchar(50) not null;

-- 插入三種方式

-- 1.僅對特定字段進(jìn)行賦值插入

INSERT INTO t_user ( id, code ) VALUES ( 888892, 'eee' );
-- 2.對所有字段進(jìn)行賦值插入
INSERT INTO `custom_sd`.`t_user `(`id`, `code`, `pid`, `name`, `delete_flag`, `create_time`, `create_user`, `update_time`, `update_user`, `standby_01`, `standby_02`, `standby_03`, `standby_04`, `standby_05`, `district_level1`) VALUES (245, '379999', '371755', '哈利路亞', 0, '2021-01-14 18:03:42', NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, '5');
-- 3.對所有字段進(jìn)行賦值插入（可不指定字段）
INSERT INTO `custom_sd`.`t_user ` VALUES (888893, '379999', '371755', '哈利路亞', 0, '2021-01-14 18:03:42', NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, '5');

-- 根據(jù)條件刪除
delete from t_user where id = 888893;
-- 多表聯(lián)合刪除(無關(guān)聯(lián)記錄匹配時，不進(jìn)行刪除，開發(fā)中需注意區(qū)分)
delete p,pp from t_a p, t_b pp where p.id = pp.PLAN_ID and pp.PRODUCT_ID = #{vo.id}
delete p,pp,e from t_a p, t_b pp,t_c e where p.id = pp.PLAN_ID and e.PLAN_ID = p.ID and pp.PRODUCT_ID = #{vo.id}

-- 修改單個或多個字段
update t_user set code = 'xxx', pid = 456 where id = 888892;
-- 修改某個值的部分字符
update t_role set PERMISSION = REPLACE(PERMISSION,'\"角色設(shè)置\"','\"角色設(shè)置\", \"信息員列表\"') where name = 'xxx';

-- 查詢列名
SELECT
?? ?GROUP_CONCAT( COLUMN_NAME SEPARATOR "," )?
FROM
?? ?information_schema.COLUMNS?
WHERE
?? ?TABLE_NAME = 't_order_ext2' and TABLE_SCHEMA = 'biz_channel';
?? ?
-- 查詢列名，并顯示駝峰別名 (僅支持單個下劃線)
SELECT
?? ?GROUP_CONCAT( CONCAT(COLUMN_NAME," ",if(LOCATE('_', "abc_bcd")>0,COLUMN_NAME,CONCAT(left(COLUMN_NAME,LOCATE('_', COLUMN_NAME)-1),UPPER(substring(COLUMN_NAME,LOCATE('_', COLUMN_NAME) + 1,1)),right(COLUMN_NAME,LENGTH(COLUMN_NAME) - LOCATE('_', COLUMN_NAME) - 1)))) SEPARATOR "," )?
FROM
?? ?information_schema.COLUMNS?
WHERE
?? ?TABLE_NAME = 't_order_ext2';
?? ?
-- 查詢列名，并顯示駝峰別名 (可支持兩個下劃線)
-- 注意：有重復(fù)數(shù)據(jù)，需取后面，可使用關(guān)鍵字去重，但去重后默認(rèn)進(jìn)行了排序
SELECT GROUP_CONCAT(CONCAT(COLUMN_NAME," ",IF (LOCATE('_',COLUMN_NAME)=0,COLUMN_NAME,CONCAT(LEFT (COLUMN_NAME,LOCATE('_',COLUMN_NAME)-1),UPPER(substring(COLUMN_NAME,LOCATE('_',COLUMN_NAME)+1,1)),IF (LOCATE('_',RIGHT (COLUMN_NAME,LENGTH(COLUMN_NAME)-LOCATE('_',COLUMN_NAME)-1))=0,RIGHT (COLUMN_NAME,LENGTH(COLUMN_NAME)-LOCATE('_',COLUMN_NAME)-1),CONCAT(LEFT (RIGHT (COLUMN_NAME,LENGTH(COLUMN_NAME)-LOCATE('_',COLUMN_NAME)-1),LOCATE('_',RIGHT (COLUMN_NAME,LENGTH(COLUMN_NAME)-LOCATE('_',COLUMN_NAME)-1))-1),UPPER(substring(RIGHT (COLUMN_NAME,LENGTH(COLUMN_NAME)-LOCATE('_',COLUMN_NAME)-1),LOCATE('_',RIGHT (COLUMN_NAME,LENGTH(COLUMN_NAME)-LOCATE('_',COLUMN_NAME)-1))+1,1)),RIGHT (RIGHT (COLUMN_NAME,LENGTH(COLUMN_NAME)-LOCATE('_',COLUMN_NAME)-1),LENGTH(RIGHT (COLUMN_NAME,LENGTH(COLUMN_NAME)-LOCATE('_',COLUMN_NAME)-1))-LOCATE('_',RIGHT (COLUMN_NAME,LENGTH(COLUMN_NAME)-LOCATE('_',COLUMN_NAME)-1))-1)))))) SEPARATOR ",") FROM information_schema.COLUMNS WHERE TABLE_NAME='imgrecord';
?? ??? ??? ?
-- 統(tǒng)計查詢 if使用方法 mybatis
? select
? ? <include refid="BaseSql"/>
? ? ,
? ? sum(if(u.is_entering = 0,1,0)) AS count,
? ? sum(if(u.is_entering = 1,1,0)) AS total,
? ? sum(if(u.is_entering = 1 and is_supplementary_data = 1,1,0)) ?AS countTotal
? ? from t_sd_info m
? ? left join t_su_info u on m.id= u.im_id
? ? where m.u_id = #{uId}