-- 查看數據庫中表的字段屬性

SELECT COLUMN_NAME 列名, COLUMN_COMMENT 名稱, COLUMN_TYPE 數據類型, IF(COLUMN_KEY='PRI', "主鍵", "非主鍵") 主鍵,

IF(IS_NULLABLE='NO', "可空", "非空") 是否為空, "" 二級注釋 , COLUMN_DEFAULT 默認值, TABLE_SCHEMA 數據庫名稱,

DATA_TYPE 字段類型, CHARACTER_MAXIMUM_LENGTH 長度 FROM INFORMATION_SCHEMA.COLUMNS

WHERE TABLE_NAME = 'TableName' AND TABLE_SCHEMA = 'DatabaseName'

--刪除數據

DELETE A FROM SYS_USER_ROLE A WHERE NOT EXISTS (SELECT 1 FROM SYS_USER B WHERE A.USER_ID = B.ID)

--刪除數據?同表刪除報錯

DELETE FROM JIANGSU_AB01 WHERE AAB004 IN (SELECT * FROM (SELECT B.AAB004 FROM JIANGSU_AB01 B GROUP BY B.AAB004 HAVING COUNT(1) > 1) B)

-- 設置GROUP_CONCAT()函數拼接長度

SET SESSION GROUP_CONCAT_MAX_LEN = 1024;

-- 表字段一列多行轉成一個字符串

SELECT GROUP_CONCAT(CONCAT(' AS "', UPPER(COLUMN_NAME), '"') SEPARATOR ', ') COL2ROW FROM INFORMATION_SCHEMA.COLUMNS

WHERE TABLE_NAME = 'TableName' AND TABLE_SCHEMA = 'DatabaseName';

--?去除空格

UPDATE JIANGSU_AB01 SET AAB031 = TRIM(REPLACE(REPLACE(REPLACE(REPLACE(AAB031, CHAR(10), ''), CHAR(13), ''), '-', ''), ' ', ''));

SHOW VARIABLES LIKE 'event_scheduler';

SELECT * FROM MYSQL.EVENT;

SHOW VARIABLES LIKE '%TIME%';

SET GLOBAL EVENT_SCHEDULER = ON;

SET TIME_ZONE = '+8:00';

SET SYSTEM_TIME_ZONE = '+8:00';

打開數據庫FEDERATED功能 建立類似ORACLE的DBLINK的表 ( CREATE TABLE TABLE_NAME(......) ENGINE = FEDERATED CONNECTION='mysql://[username]:[password]@[location]:[port]/[db-name]/[table-name] 待測試)

-- 重復數據設置成1

UPDATE?TableName SET COLUMNNAME?='1' WHERE COLUMNNAME?IN (SELECT COLUMNNAME?FROM (SELECT COLUMNNAME?, COUNT(1) FROM TableName?GROUP BY COLUMNNAME?HAVING COUNT(1) > 1) A)

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