目錄

• 一、基本信息查看
  • 1. 表描述
• 二、表操作
  • 1. 查看建表語句
  • 2.查看表
  • 3. 創建表
  • 4. 更新表
  • 5. 刪除表
  • 6. 重命名表
• 三、索引操作
  • 1. 查看索引
  • 2. 創建索引
  • 3. 修改索引
  • 4. 刪除索引
• 四、記錄操作
  • 1. 查詢記錄
  • 2. 添加記錄
  • 3. 更新記錄
  • 4. 刪除記錄

一、基本信息查看

1. 表描述

DESCRIBE `table_name`;

二、表操作

1. 查看建表語句

SHOW CREATE TABLE `table_name`;

2.查看表

SHOW TABLES;

3. 創建表

CREATE TABLE `table_name` (`c_id` int(11) unsigned NOT NULL AUTO_INCREMENT COMMENT '唯一ID',`c_is_deleted` tinyint(1) NOT NULL DEFAULT '0' COMMENT '邏輯刪除',`c_update_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '更新時間',`c_create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '創建時間',PRIMARY KEY (`c_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='table_name' CREATE TABLE IF NOT EXISTS `table_name` (`c_id` bigint(20) unsigned NOT NULL COMMENT '唯一ID',`c_uid` char(11) NOT NULL DEFAULT '' COMMENT 'uid列',`c_char` char(11) NOT NULL DEFAULT '' COMMENT 'char列',`c_varchar1` varchar(30) NOT NULL DEFAULT '' COMMENT 'varchar列',`c_varchar2` varchar(300) CHARACTER SET utf8mb4 NOT NULL DEFAULT '' COMMENT 'varchar列，單獨設置字符集',`c_text` text CHARACTER SET utf8mb4 NOT NULL COMMENT 'text列，單獨設置字符集',`c_tinyint` tinyint(1) NOT NULL DEFAULT '0' COMMENT 'tinyint，當枚舉用(0A 1B 2C)',`c_enum` enum('0','1') NOT NULL DEFAULT '0' COMMENT 'enum，枚舉用',`c_json` json NOT NULL COMMENT 'json類型列',`c_is_deleted` tinyint(1) NOT NULL DEFAULT '0' COMMENT '邏輯刪除',`c_update_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '更新時間',`c_create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '創建時間',PRIMARY KEY (`c_id`),KEY `inx_c_uid` (`c_uid`) USING BTREE,UNIQUE KEY `udx_c1_c2` (`c_char`,`c_tinyint`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='table_name';

4. 更新表

• 增加列

ALTER TABLE `table_name` ADD `c_column` tinyint(1) not null DEFAULT 0 COMMENT '新增列';

• 修改列

ALTER TABLE `table_name` MODIFY COLUMN `c_varchar1` VARCHAR ( 300 ) NOT NULL DEFAULT '' COMMENT '標識符' AFTER `c_varchar2`;

• 刪除列

ALTER TABLE `table_name` DROP COLUMN `c_column`;

5. 刪除表

DROP TABLE if EXISTS `table_name`;

6. 重命名表

RENAME TABLE `table_name` TO `table_name_2`;

三、索引操作

1. 查看索引

SHOW INDEX FROM table_name [FROM db_name]

2. 創建索引

• 語法

CREATE [UNIQUE|FULLTEXT|SPATIAL] INDEX index_name [USING index_type] ON table_name (index_col_name, ...) CREATE UNIQUE INDEX idx_uid ON `table_name` (`c_uid`);-- TEXT和BLOB要指定長度 CREATE UNIQUE INDEX idx_text ON `table_name` (`c_text`(6));

• ALTER TABLE方式

ALTER TABLE table_name ADD [UNIQUE|FULLTEXT|SPATIAL] INDEX index_name (index_col_name,...) [USING index_type] ALTER TABLE `table_name` ADD PRIMARY KEY ( `c_uid` )ALTER TABLE `table_name` ADD INDEX `udx_c1_c2` ( `c_char`(n), `c_tinyint` ) USING BTREE;

3. 修改索引

ALTER TABLE `table_name` DROP INDEX `udx_c1_c2`, ADD INDEX `udx_c1_c2` ( `c_char`, `c_tinyint`, `c_is_deleted` ) USING HASH;

4. 刪除索引

ALTER TABLE table_name DROP PRIMARY KEY;DROP INDEX `idx_name` ON `table_name`;ALTER TABLE `table_name` DROP INDEX `udx_c1_c2`;

四、記錄操作

1. 查詢記錄

• 簡單查詢

子句順序：SELETC、 FROM、 WHERE、 GROUP BY、 HAVING、 ORDER BY、 LIMIT

SELECT * FROM table_name WHERE ... ORDER BY c_column1,c_column2 DESC;

• 模糊查詢
  特殊字符要轉義% _

SELECT * FROM table_name WHERE c_column LIKE CONCAT('first','second','third');SELECT * FROM table_name WHERE c_column LIKE CONCAT('%','_','%');

• 分組查詢

  WHERE過濾行, HAVING過濾分組

SELECT GROUP_CONCAT(c_column) FROM table_name WHERE c_is_deleted=0 GROUP BY c_column1, c_column2 HAVING COUNT(c_column3) >= 2;-- 可能報錯：incompatible with sql_mode=only_full_group_by SELECT GROUP_CONCAT(c_column) FROM table_name WHERE c_is_deleted=0 GROUP BY c_column1, c_column2 HAVING COUNT(c_column3) >= 2 ORDER BY c_order DESC;SELECT GROUP_CONCAT(c_id),COUNT(*) FROM table_name GROUP BY c_type WITH ROLLUP;

• 分頁查詢

  檢索出來的第一行為行0而不是行1。

-- 查詢兩條記錄，開始行1 SELECT * FROM table_name LIMIT 1, 2;

• 計算字段和函數

（1）計算字段

SELECT 1+1 AS result;SELECT CONCAT('first', c_column, 'third') AS c_alias_name FROM table_name;SELECT CONCAT('first', TRIM(c_column), 'third') AS c_alias_name FROM table_name;

（2）處理函數

SELECT UUID() AS `uid`;SELECT UPPER('a');SELECT DATE(c_create_time) AS `date`, TIME(c_create_time) AS `time` FROM table_name;

（3）聚集函數

SELECT COUNT( * ),MIN( c_column ),MAX( c_column ),AVG( c_column ) FROM table_name;SELECT SUM( c_column1 * c_column2 ) FROM table_name;

• 子查詢

SELECT * FROM table_name1 WHERE c_column IN ( SELECT c_column FROM table_name2WHERE c_is_deleted = 1 );-- 計算字段作為子查詢 SELECT table_name1.c_name,( SELECT COUNT( * ) FROM table_name2 WHERE table_name2.c_key = table_name1.c_key ) AS nums FROM table_name1 WHERE c_is_deleted = 0;

• 聯結查詢

(1) 自聯結

SELECT t1.c_id, t1.c_name FROM table_name AS t1, table_name AS t2 WHERE t1.c_id = t2.c_id AND t2.c_key = '';

(2) 自然聯結

SELECT t1.c_id, t1.c_name FROM table_name1 AS t1, table_name2 AS t2 WHERE t1.c_id = t2.c_id AND t2.c_key = '';

(3) 外部聯結

SELECTtable_name1.c_id,table_name1.c_name,table_name2.c_name FROM table_name1 LEFT JOIN table_name2 ON table_name2.c_key = table_name1.c_key WHERE ...;

• 查詢結果case when then else end用法

(1) 語法

--簡單Case函數 CASE sex WHEN '1' THEN '男' WHEN '2' THEN '女' ELSE '其他' END --Case搜索函數, CASE WHEN sex = '1' THEN '男' WHEN sex = '2' THEN '女' ELSE '其他' END

(2) 示例

SELECT `name`, CASE `name` WHEN 'sam' THEN 'yong' WHEN 'lee' THEN 'handsome' ELSE 'good' END AS `alias` FROM `table_name`;SELECT `name`, CASEWHEN birthday < '1981' THEN 'old' WHEN birthday > '1988' THEN 'yong' ELSE 'ok' END AS `yorn` FROM `table_name`;

2. 添加記錄

• 簡單插入

INSERT INTO table_name ( column1, column2 ) VALUES ( value1, value2 );

• 批量插入

INSERT INTO table_name ( column1, column2 ) VALUES( value1, value2 ),( value1, value2 );

• INSERT SELECT插入

INSERT INTO table_name ( column1, column2 )SELECT column1, column2 FROM table_name WHERE c_id=1;

3. 更新記錄

UPDATE `table_name` SET `c_varchar1` = 'string',`c_update_time` = CURRENT_TIMESTAMP WHERE `c_id` = 1;

4. 刪除記錄

• DELETE方式

DELETE FROM `table_name` WHERE `c_id`=1;

• TRUNCATE方式-清空表-慎用

-- 刪除原表再新建表TRUNCATE TABLE `table_name`

轉載于:https://www.cnblogs.com/flylinran/p/10171508.html

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