{"id":241,"date":"2023-02-24T06:01:10","date_gmt":"2023-02-23T22:01:10","guid":{"rendered":"https:\/\/www.appblog.cn\/?p=241"},"modified":"2023-04-30T15:20:26","modified_gmt":"2023-04-30T07:20:26","slug":"mysql-alter-command","status":"publish","type":"post","link":"https:\/\/www.appblog.cn\/index.php\/2023\/02\/24\/mysql-alter-command\/","title":{"rendered":"MySQL ALTER\u547d\u4ee4"},"content":{"rendered":"

\u5f53\u6211\u4eec\u9700\u8981\u4fee\u6539\u6570\u636e\u8868\u540d\u6216\u8005\u4fee\u6539\u6570\u636e\u8868\u5b57\u6bb5\u65f6\uff0c\u5c31\u9700\u8981\u4f7f\u7528\u5230MySQL ALTER<\/code>\u547d\u4ee4\u3002<\/p>\n

\u521b\u5efa\u4e00\u5f20\u8868\uff0c\u8868\u540d\u4e3a\uff1atestalter_tbl<\/code><\/p>\n

<\/p>\n

root@host# mysql -u root -p password;\nEnter password:*******\nmysql> use appblog;\nDatabase changed\nmysql> create table testalter_tbl\n    -> (\n    -> i INT,\n    -> c CHAR(1)\n    -> );\nQuery OK, 0 rows affected (0.05 sec)\nmysql> SHOW COLUMNS FROM testalter_tbl;\n+-------+---------+------+-----+---------+-------+\n| Field | Type    | Null | Key | Default | Extra |\n+-------+---------+------+-----+---------+-------+\n| i     | int(11) | YES  |     | NULL    |       |\n| c     | char(1) | YES  |     | NULL    |       |\n+-------+---------+------+-----+---------+-------+\n2 rows in set (0.00 sec)<\/code><\/pre>\n
\u5220\u9664\uff0c\u6dfb\u52a0\u6216\u4fee\u6539\u8868\u5b57\u6bb5<\/h2>\n
\u5982\u4e0b\u547d\u4ee4\u4f7f\u7528ALTER<\/code>\u547d\u4ee4\u53caDROP<\/code>\u5b50\u53e5\u6765\u5220\u9664\u4ee5\u4e0a\u521b\u5efa\u8868\u7684i<\/code>\u5b57\u6bb5\uff1a<\/p>\n
mysql> ALTER TABLE testalter_tbl DROP i;<\/code><\/pre>\n
\u5982\u679c\u6570\u636e\u8868\u4e2d\u53ea\u5269\u4f59\u4e00\u4e2a\u5b57\u6bb5\u5219\u65e0\u6cd5\u4f7f\u7528DROP<\/code>\u6765\u5220\u9664\u5b57\u6bb5<\/p>\n
MySQL\u4e2d\u4f7f\u7528ADD<\/code>\u5b50\u53e5\u6765\u5411\u6570\u636e\u8868\u4e2d\u6dfb\u52a0\u5217\uff0c\u5982\u4e0b\u5b9e\u4f8b\u5728\u8868testalter_tbl<\/code>\u4e2d\u6dfb\u52a0i<\/code>\u5b57\u6bb5\uff0c\u5e76\u5b9a\u4e49\u6570\u636e\u7c7b\u578b\uff1a<\/p>\n
mysql> ALTER TABLE testalter_tbl ADD i INT;<\/code><\/pre>\n
\u6267\u884c\u4ee5\u4e0a\u547d\u4ee4\u540e\uff0ci<\/code>\u5b57\u6bb5\u4f1a\u81ea\u52a8\u6dfb\u52a0\u5230\u6570\u636e\u8868\u5b57\u6bb5\u7684\u672b\u5c3e\uff1a<\/p>\n
mysql> SHOW COLUMNS FROM testalter_tbl;\n+-------+---------+------+-----+---------+-------+\n| Field | Type    | Null | Key | Default | Extra |\n+-------+---------+------+-----+---------+-------+\n| c     | char(1) | YES  |     | NULL    |       |\n| i     | int(11) | YES  |     | NULL    |       |\n+-------+---------+------+-----+---------+-------+\n2 rows in set (0.00 sec)<\/code><\/pre>\n
\u5982\u679c\u9700\u8981\u6307\u5b9a\u65b0\u589e\u5b57\u6bb5\u7684\u4f4d\u7f6e\uff0c\u53ef\u4ee5\u4f7f\u7528MySQL\u63d0\u4f9b\u7684\u5173\u952e\u5b57FIRST<\/code>\uff08\u8bbe\u5b9a\u4f4d\u7b2c\u4e00\u5217\uff09\uff0cAFTER \u5b57\u6bb5\u540d<\/code>\uff08\u8bbe\u5b9a\u4f4d\u4e8e\u67d0\u4e2a\u5b57\u6bb5\u4e4b\u540e\uff09<\/p>\n
\u5c1d\u8bd5\u4ee5\u4e0bALTER TABLE<\/code>\u8bed\u53e5\uff0c\u5728\u6267\u884c\u6210\u529f\u540e\uff0c\u4f7f\u7528SHOW COLUMNS<\/code>\u67e5\u770b\u8868\u7ed3\u6784\u7684\u53d8\u5316\uff1a<\/p>\n
ALTER TABLE testalter_tbl DROP i;\nALTER TABLE testalter_tbl ADD i INT FIRST;\nALTER TABLE testalter_tbl DROP i;\nALTER TABLE testalter_tbl ADD i INT AFTER c;<\/code><\/pre>\n
FIRST<\/code>\u548cAFTER<\/code>\u5173\u952e\u5b57\u53ef\u7528\u4e8eADD<\/code>\u4e0eMODIFY<\/code>\u5b50\u53e5\uff0c\u6240\u4ee5\u5982\u679c\u60f3\u91cd\u7f6e\u6570\u636e\u8868\u5b57\u6bb5\u7684\u4f4d\u7f6e\u5c31\u9700\u8981\u5148\u4f7f\u7528DROP<\/code>\u5220\u9664\u5b57\u6bb5\u7136\u540e\u4f7f\u7528ADD<\/code>\u6765\u6dfb\u52a0\u5b57\u6bb5\u5e76\u8bbe\u7f6e\u4f4d\u7f6e\u3002<\/p>\n
\u4fee\u6539\u5b57\u6bb5\u7c7b\u578b\u53ca\u540d\u79f0<\/h2>\n
\u5982\u679c\u9700\u8981\u4fee\u6539\u5b57\u6bb5\u7c7b\u578b\u53ca\u540d\u79f0\uff0c\u53ef\u4ee5\u5728ALTER<\/code>\u547d\u4ee4\u4e2d\u4f7f\u7528MODIFY<\/code>\u6216CHANGE<\/code>\u5b50\u53e5\u3002<\/p>\n
\u4f8b\u5982\uff0c\u628a\u5b57\u6bb5c<\/code>\u7684\u7c7b\u578b\u4eceCHAR(1)<\/code>\u6539\u4e3aCHAR(10)<\/code>\uff0c\u53ef\u4ee5\u6267\u884c\u4ee5\u4e0b\u547d\u4ee4:<\/p>\n
mysql> ALTER TABLE testalter_tbl MODIFY c CHAR(10);<\/code><\/pre>\n
\u4f7f\u7528CHANGE<\/code>\u5b50\u53e5\uff0c\u8bed\u6cd5\u6709\u5f88\u5927\u7684\u4e0d\u540c\u3002\u5728CHANGE<\/code>\u5173\u952e\u5b57\u4e4b\u540e\uff0c\u7d27\u8ddf\u7740\u7684\u662f\u8981\u4fee\u6539\u7684\u5b57\u6bb5\u540d\uff0c\u7136\u540e\u6307\u5b9a\u65b0\u5b57\u6bb5\u540d\u53ca\u7c7b\u578b\u3002\u5c1d\u8bd5\u5982\u4e0b\u5b9e\u4f8b\uff1a<\/p>\n
mysql> ALTER TABLE testalter_tbl CHANGE i j BIGINT;\nmysql> ALTER TABLE testalter_tbl CHANGE j j INT;<\/code><\/pre>\n
ALTER TABLE \u5bf9 Null \u503c\u548c\u9ed8\u8ba4\u503c\u7684\u5f71\u54cd<\/h2>\n
\u5f53\u4fee\u6539\u5b57\u6bb5\u65f6\uff0c\u53ef\u4ee5\u6307\u5b9a\u662f\u5426\u5305\u542b\u503c\u6216\u8005\u662f\u5426\u8bbe\u7f6e\u9ed8\u8ba4\u503c<\/p>\n
\u4ee5\u4e0b\u5b9e\u4f8b\uff0c\u6307\u5b9a\u5b57\u6bb5j<\/code>\u4e3aNOT NULL<\/code>\u4e14\u9ed8\u8ba4\u503c\u4e3a100<\/p>\n
mysql> ALTER TABLE testalter_tbl \n    -> MODIFY j BIGINT NOT NULL DEFAULT 100;<\/code><\/pre>\n
\u5982\u679c\u4e0d\u8bbe\u7f6e\u9ed8\u8ba4\u503c\uff0cMySQL\u4f1a\u81ea\u52a8\u8bbe\u7f6e\u8be5\u5b57\u6bb5\u9ed8\u8ba4\u4e3a NULL<\/p>\n
\u4fee\u6539\u5b57\u6bb5\u9ed8\u8ba4\u503c<\/h2>\n
\u53ef\u4ee5\u4f7f\u7528ALTER<\/code>\u6765\u4fee\u6539\u5b57\u6bb5\u7684\u9ed8\u8ba4\u503c\uff0c\u5c1d\u8bd5\u4ee5\u4e0b\u5b9e\u4f8b\uff1a<\/p>\n
mysql> ALTER TABLE testalter_tbl ALTER i SET DEFAULT 1000;\nmysql> SHOW COLUMNS FROM testalter_tbl;\n+-------+---------+------+-----+---------+-------+\n| Field | Type    | Null | Key | Default | Extra |\n+-------+---------+------+-----+---------+-------+\n| c     | char(1) | YES  |     | NULL    |       |\n| i     | int(11) | YES  |     | 1000    |       |\n+-------+---------+------+-----+---------+-------+\n2 rows in set (0.00 sec)<\/code><\/pre>\n
\u4e5f\u53ef\u4ee5\u4f7f\u7528ALTER<\/code>\u547d\u4ee4\u53caDROP<\/code>\u5b50\u53e5\u6765\u5220\u9664\u5b57\u6bb5\u7684\u9ed8\u8ba4\u503c\uff0c\u5982\u4e0b\u5b9e\u4f8b\uff1a<\/p>\n
mysql> ALTER TABLE testalter_tbl ALTER i DROP DEFAULT;\nmysql> SHOW COLUMNS FROM testalter_tbl;\n+-------+---------+------+-----+---------+-------+\n| Field | Type    | Null | Key | Default | Extra |\n+-------+---------+------+-----+---------+-------+\n| c     | char(1) | YES  |     | NULL    |       |\n| i     | int(11) | YES  |     | NULL    |       |\n+-------+---------+------+-----+---------+-------+\n2 rows in set (0.00 sec)<\/code><\/pre>\n
\u4fee\u6539\u6570\u636e\u8868\u7c7b\u578b<\/h2>\n
\u53ef\u4ee5\u4f7f\u7528ALTER<\/code>\u547d\u4ee4\u53caTYPE<\/code>\u5b50\u53e5\u6765\u5b8c\u6210\u3002\u5c1d\u8bd5\u4ee5\u4e0b\u5b9e\u4f8b\uff0c\u6211\u4eec\u5c06\u8868testalter_tbl<\/code>\u7684\u7c7b\u578b\u4fee\u6539\u4e3aMYISAM<\/code>\uff1a<\/p>\n
\u6ce8\u610f\uff1a\u67e5\u770b\u6570\u636e\u8868\u7c7b\u578b\u53ef\u4ee5\u4f7f\u7528SHOW TABLE STATUS<\/code>\u8bed\u53e5<\/p>\n
mysql> ALTER TABLE testalter_tbl ENGINE = MYISAM;\nmysql>  SHOW TABLE STATUS LIKE 'testalter_tbl'\\G\n*************************** 1. row ****************\n           Name: testalter_tbl\n           Type: MyISAM\n     Row_format: Fixed\n           Rows: 0\n Avg_row_length: 0\n    Data_length: 0\nMax_data_length: 25769803775\n   Index_length: 1024\n      Data_free: 0\n Auto_increment: NULL\n    Create_time: 2007-06-03 08:04:36\n    Update_time: 2007-06-03 08:04:36\n     Check_time: NULL\n Create_options:\n        Comment:\n1 row in set (0.00 sec)<\/code><\/pre>\n
\u4fee\u6539\u8868\u540d<\/h2>\n
\u5982\u679c\u9700\u8981\u4fee\u6539\u6570\u636e\u8868\u7684\u540d\u79f0\uff0c\u53ef\u4ee5\u5728ALTER TABLE<\/code>\u8bed\u53e5\u4e2d\u4f7f\u7528RENAME<\/code>\u5b50\u53e5\u6765\u5b9e\u73b0<\/p>\n
\u5c1d\u8bd5\u4ee5\u4e0b\u5b9e\u4f8b\u5c06\u6570\u636e\u8868testalter_tbl<\/code>\u91cd\u547d\u540d\u4e3aalter_tbl<\/code>\uff1a<\/p>\n
mysql> ALTER TABLE testalter_tbl RENAME TO alter_tbl;<\/code><\/pre>\n
ALTER<\/code>\u547d\u4ee4\u8fd8\u53ef\u4ee5\u7528\u6765\u521b\u5efa\u53ca\u5220\u9664MySQL\u6570\u636e\u8868\u7684\u7d22\u5f15<\/p>\n
ALTER\u5176\u4ed6\u7528\u9014<\/h2>\n
\u4fee\u6539\u5b58\u50a8\u5f15\u64ce\uff1a\u4fee\u6539\u4e3amyisam<\/p>\n
alter table tableName engine=myisam;<\/code><\/pre>\n
\u5220\u9664\u5916\u952e\u7ea6\u675f\uff1akeyName\u662f\u5916\u952e\u522b\u540d<\/p>\n
alter table tableName drop foreign key keyName;<\/code><\/pre>\n
\u4fee\u6539\u5b57\u6bb5\u7684\u76f8\u5bf9\u4f4d\u7f6e\uff1a\u8fd9\u91ccname1\u4e3a\u60f3\u8981\u4fee\u6539\u7684\u5b57\u6bb5\uff0ctype1\u4e3a\u8be5\u5b57\u6bb5\u539f\u6765\u7c7b\u578b\uff0cfirst\u548cafter\u4e8c\u9009\u4e00\uff0c\u8fd9\u5e94\u8be5\u663e\u800c\u6613\u89c1\uff0cfirst\u653e\u5728\u7b2c\u4e00\u4f4d\uff0cafter\u653e\u5728name2\u5b57\u6bb5\u540e\u9762<\/p>\n
alter table tableName modify name1 type1 first|after name2;<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
\u5f53\u6211\u4eec\u9700\u8981\u4fee\u6539\u6570\u636e\u8868\u540d\u6216\u8005\u4fee\u6539\u6570\u636e\u8868\u5b57\u6bb5\u65f6\uff0c\u5c31\u9700\u8981\u4f7f\u7528\u5230MySQL ALTER\u547d\u4ee4\u3002 \u521b\u5efa\u4e00\u5f20\u8868\uff0c\u8868\u540d\u4e3a\uff1ate […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[13],"tags":[],"class_list":["post-241","post","type-post","status-publish","format-standard","hentry","category-mysql"],"_links":{"self":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/posts\/241","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/comments?post=241"}],"version-history":[{"count":0,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/posts\/241\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/media?parent=241"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/categories?post=241"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/tags?post=241"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}