When you add a unique constraint to a table MySQL creates a corresponding BTREE index to the database. The following SHOW INDEX statement displays all indexes created on the suppliers table. 1 SHOW INDEX FROM classicmodels.suppliers; As you see, there are two BTREE indexes corresponding to th...
alter table student add address varchar(1000); 修改name列,使其长度为30: alter table student modify name varchar(30); 删除address列,一次只能删一列: alter table student drop address; 表名改为user: rename table student to user; 查看表格的创建细节: show create table user; 修改表的字符集为gbk:...
CREATE TABLE 新表名 AS (SELECT * FROM 被赋值表名); 1. 如果是只复制表的结构,不复制数据: CREATE TABLE 新表名 LIKE 被赋值表名; 1. 修改表名 alter table 表名 RENAME [TO|AS] 新的表名; eg: alter table stu RENAME TO student; 1. 2. 3. 添加列: ALTER TABLE <表名> ADD COLUMN <列...
#表级约束ALTERTABLEstuinfoADDPRIMARYKEY(id);4.添加唯一键 #列级约束ALTERTABLEstuinfo MODIFYCOLUMNseatINTUNIQUE; #表级约束ALTERTABLEstuinfoADDUNIQUE(seat);5.添加外键 ALTERTABLEstuinfoADDCONSTRAINTfk_stuinfo_majorFOREIGNKEY(majorid)REFERENCESmajor(id); 删除约束 #1.删除非空约束ALTERTABLEstuinfo MO...
(auto_increment)自增长(foreign key)外键(在表之间建立物理链接)create table * (id int primary key ,name varchat(50) not null unique);(不同约束用空格隔开) 注意:可以用修改数据类型的方式修改约束。 constraint fk_emp_dept foreign key(dep_id) references dept(id); 创表的时候作为列一样的地方使用...
For more information, see Section 13.1.18.3, “CREATE TABLE ... LIKE Statement”. [AS] query_expression To create one table from another, add a SELECT statement at the end of the CREATE TABLE statement: CREATE TABLE new_tbl AS SELECT * FROM orig_tbl; For more information, see Secti...
CREATE INDEX enables you to add indexes to existing tables. CREATE INDEX is mapped to an ALTER TABLE statement to create indexes. See Section 15.1.9, “ALTER TABLE Statement”. CREATE INDEX cannot be used to create a PRIMARY KEY; use ALTER TABLE instead. For more information about indexes...
Enable primary key and unique key supplemental logging at the database level: exec rdsadmin.rdsadmin_util.alter_supplemental_logging('ADD', 'PRIMARY KEY'); exec rdsadmin.rdsadmin_util.alter_supplemental_logging('ADD', 'UNIQUE'); Enable table-level supplemental l...
define ER_DUP_UNIQUE 1169 "Can't write, because of unique constraint, to table '%-.64s'", define ER_BLOB_KEY_WITHOUT_LENGTH 1170 "BLOB/TEXT column '%-.64s' used in key specification without a key length", define ER_PRIMARY_CANT_HAVE_NULL 1171 ...
建完表之后追加主键：ALTER TABLE student ADD CONSTRAINT pk_id PRIMARY KEY(s_id);删除主键：ALTER ...