varchar,nchar, andnvarchardata types. To change the collation of a user-defined alias data type column, you must execute separate ALTER TABLE statements to change the column to a SQL Server system data type and change its collation, and then change the column back to an alias data type....
ALTER TABLE modifies a table definition by altering, adding, or dropping columns and constraints. ALTER TABLE also reassigns and rebuilds partitions, or disables and enables constraints and triggers.
修改表,包括修改表的定义、重命名表、重命名表中指定的列、重命名表的约束、设置表的所属模式、添加/更新多个列、打开/关闭行访问控制开关。只有表的所有者或者被授予了表ALTER权限的用户有权限执行ALTER TABLE命令,系统管理员默认拥有此权限。若要修改表的所有者或者修改
table_name | table_name } { ALTER COLUMN column_name { [ type_schema_name. ] type_name [ ( { precision [ , scale ] } ) ] [ COLLATE collation_name ] [ NULL | NOT NULL ] } | ALTER INDEX index_name { [ type_schema_name. ] type_name REBUILD [ [ NONCLUSTERED ] WITH ( ...
[VISIBLE|INVISIBLE]|CHANGE[COLUMN]column_name column_definition|DROP[COLUMN]column_name|DROP{INDEX|KEY} index_name|DROP{PARTITION|SUBPARTITION} partition_name_list|DROPTABLEGROUP|DROPFOREIGNKEYfk_name|MODIFY[COLUMN]column_definition|RENAME[TO]table_name|RENAME{INDEX|KEY} old_index_nameTOnew_index_...
其语法可表示如下:CREATE DATABASE database_name [ ON [ < filespec > [1,...n ] ] [ , < filegroup > [1,...n ] ] ] [ LOG ON { < filespec > [1,...n ] } ] [ COLLATE collation_name ] [ FOR LOAD | FOR ATTACH ] 其中,< filespec >定义如下所示。
table_options: table_option[[,]table_option] ... table_option: AUTO_INCREMENT[=]value|AVG_ROW_LENGTH[=]value|[DEFAULT]CHARACTERSET[=]charset_name|CHECKSUM[=]{0|1}|[DEFAULT]COLLATE[=]collation_name|COMMENT[=]'string'|COMPRESSION[=]{'ZLIB'|'LZ4'|'NONE'}|CONNECTION[=]'connect_string'|...
obclient>ALTERTABLEt2 CHANGECOLUMNd cINT; 增加、删除列。 增加列前,执行DESCRIBE test;命令查看表信息,如下图所示: 1 执行以下命令增加c3列。 obclient>ALTERTABLEtestADDc3INTEGER; 增加列后,执行DESCRIBE test;命令查看表信息,如下图所示: 执行以下命令删除c3列。
CHANGECOLUMN[IFEXISTS] MODIFYCOLUMN[IFEXISTS]DROPINDEX [IFEXISTS] 当使用了IF EXISTS或IF NOT EXISTS时,当满足存在或不存在的条件时,查询将不会产生任何错误。 基本描述 ALTER TABLE语句可以改变已存在表的结构。例如,可以增减字段、创建或销毁索引、修改字段类型、重命名字段或重命名表自身。还可以改变表的注释以...
You can also change characteristics such as the storage engine used for the table or the table comment. To use ALTER TABLE, you need ALTER, CREATE, and INSERT privileges for the table. Renaming a table requires ALTER and DROP on the old table, ALTER, CREATE, and INSERT on the new table...