外鍵

查詢一個表的主鍵是哪些表的外鍵

SELECT

TABLE_NAME,

COLUMN_NAME,

CONSTRAINT_NAME,

REFERENCED_TABLE_NAME,

REFERENCED_COLUMN_NAME

FROM

INFORMATION_SCHEMA.KEY_COLUMN_USAGE

WHERE

TABLE_SCHEMA = 'mydbname'

AND REFERENCED_TABLE_NAME = '表名';

導出所有外鍵語句

SELECT

CONCAT('ALTER TABLE ', TABLE_NAME, ' ADD CONSTRAINT ', CONSTRAINT_NAME, ' FOREIGN KEY (', COLUMN_NAME, ') REFERENCES ', REFERENCED_TABLE_NAME, '(', REFERENCED_COLUMN_NAME, ') ON DELETE CASCADE ON UPDATE CASCADE;')

FROM

INFORMATION_SCHEMA.KEY_COLUMN_USAGE

WHERE

TABLE_SCHEMA = 'mydbname'

AND REFERENCED_TABLE_NAME IS NOT NULL;

刪除所有外鍵語句

SELECT

CONCAT('ALTER TABLE ', TABLE_NAME, ' DROP FOREIGN KEY ', CONSTRAINT_NAME, ';')

FROM

INFORMATION_SCHEMA.KEY_COLUMN_USAGE

WHERE

TABLE_SCHEMA = 'mydbname'

AND REFERENCED_TABLE_NAME IS NOT NULL;

自增

導出創建自增字段的語句

SELECT

CONCAT( 'ALTER TABLE `', TABLE_NAME, '` ', 'MODIFY COLUMN `', COLUMN_NAME, '` ', UPPER( COLUMN_TYPE ), ' NOT NULL AUTO_INCREMENT COMMENT "',COLUMN_COMMENT,'";' ) as 'ADD_AUTO_INCREMENT'

FROM

information_schema.COLUMNS

WHERE

TABLE_SCHEMA = 'mydbname'

AND EXTRA = UPPER( 'AUTO_INCREMENT' )

ORDER BY

TABLE_NAME ASC;

創建刪除所有自增字段

SELECT

CONCAT( 'ALTER TABLE `', TABLE_NAME, '` ', 'MODIFY COLUMN `', COLUMN_NAME, '` ', UPPER( COLUMN_TYPE ), ' NOT NULL;' ) as 'DELETE_AUTO_INCREMENT'

FROM

information_schema.COLUMNS

WHERE

TABLE_SCHEMA = 'mydbname'

AND EXTRA = UPPER( 'AUTO_INCREMENT' )

ORDER BY

TABLE_NAME ASC;

索引

導出所有索引

SELECT

CONCAT(

'ALTER TABLE `',

TABLE_NAME,

'` ',

'ADD ',

IF

(

NON_UNIQUE = 1,

CASE

UPPER( INDEX_TYPE )

WHEN 'FULLTEXT' THEN

'FULLTEXT INDEX'

WHEN 'SPATIAL' THEN

'SPATIAL INDEX' ELSE CONCAT( 'INDEX `', INDEX_NAME, '` USING ', INDEX_TYPE )

END,

IF

(

UPPER( INDEX_NAME ) = 'PRIMARY',

CONCAT( 'PRIMARY KEY USING ', INDEX_TYPE ),

CONCAT( 'UNIQUE INDEX `', INDEX_NAME, '` USING ', INDEX_TYPE ))),

CONCAT( '(`', COLUMN_NAME, '`)' ),

';'

) AS 'ADD_ALL_INDEX'

FROM

information_schema.STATISTICS

WHERE

TABLE_SCHEMA = 'mydbname'

ORDER BY

TABLE_NAME ASC,

INDEX_NAME ASC;

刪除所有索引

SELECT

CONCAT( 'ALTER TABLE `', TABLE_NAME, '` ', CONCAT( 'DROP ', IF ( UPPER( INDEX_NAME ) = 'PRIMARY', 'PRIMARY KEY', CONCAT( 'INDEX `', INDEX_NAME, '`' ))), ';' ) AS 'DELETE_ALL_INDEX'

FROM

information_schema.STATISTICS

WHERE

TABLE_SCHEMA = 'mydbname'

ORDER BY

TABLE_NAME ASC;

數據合并

在數據遷移合并的時候，比較棘手的是不同數據庫主鍵重復，那么我們就要批量修改主鍵的值，為了避免重復我們可以把自增的數字改為字符串

步驟基本上有以下幾步

取消主鍵自增

刪除所有外鍵

修改主鍵字段為varchar

添加所有外鍵

修改主鍵的值

合并數據

修改主鍵值的時候要注意

如果包含id和pid這種自關聯的情況下是不能直接修改值的，就需要先刪除約束再添加。

比如

刪除自約束

ALTER TABLE `t_director` DROP FOREIGN KEY `fk_directorpid`;

修改值

update t_director set directorid=directorid+100000000;

update t_director set directorid=CONV(directorid,10,36);

update t_director set directorpid=directorpid+100000000 WHERE directorpid is not null;

update t_director set directorpid=CONV(directorpid,10,36) WHERE directorpid is not null;

添加自約束

ALTER TABLE t_director ADD CONSTRAINT fk_directorpid FOREIGN KEY (directorpid) REFERENCES t_director(directorid) ON DELETE CASCADE ON UPDATE CASCADE;

注意

CONV(directorpid,10,36)后兩個參數為原數字進制和要轉換后的進制。

第一個參數只要內容是數字就算類型為varchar也可以轉換。

以上就是Mysql中索引和約束的示例語句的詳細內容，更多關于MySQL 索引和約束的資料請關注免費資源網其它相關文章！

總結

以上是生活随笔為你收集整理的mysql中索引约束有哪些_Mysql中索引和约束的示例语句的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。