DROP TABLE IF EXISTS `mail_model_extend`;create TABLE mail_model_extend(id int(6) auto_increment not null primary key,rid varchar(50) not null,content varchar(2000),INDEX (RID),FOREIGN KEY (RID) REFERENCES mail_model(ID) ON DELETE CASCADE ON UPDATE CASCADE)ENGINE=InnoDB DEFAULT CHARSET=gb...
{ PLAIN | EXTERNAL | EXTENDED | MAIN } ADD table_constraint [ NOT VALID ] ADD table_constraint_using_index ALTER CONSTRAINT constraint_name [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ] VALIDATE CONSTRAINT constraint_name DROP CONSTRAINT [ IF EXISTS ] constraint_...
DROP TABLE IF EXISTS `mail_model_extend`;create TABLE mail_model_extend(id int(6) auto_increment not null primary key,rid varchar(50) not null,content varchar(2000),INDEX (RID),FOREIGN KEY (RID) REFERENCES mail_model(ID) ON DELETE CASCADE ON UPDATE CASCADE)ENGINE=InnoDB DEFAULT CHARSET=gb...
ALTER TABLE student MODIFY COLUMN seat INT UNIQUE; 1. #删除默认约束 ALTER TABLE student MODIFY COLUMN gender CHAR(1) CHECK(gender='男' OR gender='女'); 1. #删除主键 ALTER TABLE student DROP PRIMARY KEY; 1. #删除唯一 ALTER TABLE student DROP INDEX seat; 1. #删除外键 ALTER TABLE studen...
yugabyte=# ALTER TABLE contacts drop CONSTRAINT IF EXISTS D_FKEY_W; NOTICE: constraint "d_fkey_w" of relation "contacts" does not exist, skipping ALTER TABLE In 2.15.3.0-b107, drop constraint with if exists gives ERROR if constraint does not exists, causing the failure, which results in...
A PRIMARY KEY constraint cannot be dropped if an XML index exists on the table. A column cannot be dropped when it is: Used in an index. Used in a CHECK, FOREIGN KEY, UNIQUE, or PRIMARY KEY constraint. Associated with a default that is defined with the DEFAULT keyword, or bound to ...
AlterTableAlterColumnStatement AlterTableAlterIndexStatement AlterTableAlterPartitionStatement AlterTableChangeTrackingModificationStatement AlterTableConstraintModificationStatement AlterTableDropTableElement AlterTableDropTableElement 建構函式 屬性 方法 AlterTableDropTableElementStatement AlterTable...
DROPDATABASEIFEXISTSmytest1;2. 对比 TRUNCATE TABLE 和 DELETE FROM 相同点：都可以实现对表中所有...
Hive常用语句 Spark大数据博客 - https://www.iteblog.com Hive常用语句 显示分区 show partitions iteblog; 添加分区 ALTER TABLE table_name ADD [IF NOT EXISTS] PARTITION partition_spec [LOCATION 'location1'] partition_spec [LOCATION 'location2'] ...; partition_spec: : (partition_column = partition...
drop table <table_name> DROP [TEMPORARY] TABLE [IF EXISTS] tbl_name [, tbl_name] ... [RESTRICT| CASCADE] TEMPORARY:用于删除临时表(推荐针对性使用),删除临时表不会结束当前的事务 IF EXISTS:用于在表不存在时,阻止错误消息的显示 [RESTRICT | CASCADE]:现在什么也不做 ...