drop可用于删除数据库(drop database 数据库名称)、删除数据表( use 数据库名称 drop table 数据表1名称,数据表2名)或删除数据表字段(use 数据库名称 alter table 数据表名称 drop column 字段名(列名称))。 值得注意的是:drop语句将删除表的结构、被依赖的约束(constrain),触发器(trigger),索引(index); 依赖...
在SQL Server中,如果要删除表中的列,可以使用ALTER TABLE语句的DROP COLUMN子句。具体步骤如下: 1. 首先,确保你有足够的权限来执行此操作。通常,只有数据库管理员或具有...
We cannot remove a column with a CHECK constraint in the table. If we want to drop a column with constraints, we first remove the constraint.SQL Serverdoes not drop a column with PRIMARY or FOREIGN KEY constraints or other dependencies. However, we can do this by using the Table Designer....
但其确实有个约束: 'DF__HIS_DRUG___ALL_I__04E4BC85' . 为什么有这个约束呢??? 终于再搜索到这篇文章时,我明白了. 因为列'ALL_INVENTORY_STATE'在创建时赋值了默认值. 所以才有这个约束的. 参考: http://blog.csdn.net/rodjohnsondoctor/article/details/7486213 http://www.ithao123.cn/content-62...
SQL DROP COLUMN Example in SSMS Here we’ll drop the columnReportsTofrom the Management Studio Object Explorer: Expand database Expand table Expand column Right click on column to drop Delete OK Or run the SQL command in the following statement: ...
syntaxsql 複製 sp_repldropcolumn [ @source_object = ] N'source_object' , [ @column = ] N'column' [ , [ @from_agent = ] from_agent ] [ , [ @schema_change_script = ] N'schema_change_script' ] [ , [ @force_invalidate_snapshot = ] force_invalidate_snapshot ]...
AlterTableAlterColumnOption AlterTableAlterColumnStatement AlterTableAlterIndexStatement AlterTableAlterPartitionStatement AlterTableChangeTrackingModificationStatement AlterTableConstraintModificationStatement AlterTableDropTableElement AlterTableDropTableElementStatement AlterTableFileTableNamespaceStatement AlterTable...
If you drop a table that contains a VARBINARY(MAX) column with the FILESTREAM attribute, any data stored in the file system will not be removed. When a ledger table is dropped, its dependent objects (the history table and the ledger view) are also dropped. A history table or a ledger ...
sql_variant类型可以用来存储除了text,ntext,image,timestamp和sql_variant之外的所有SQL Server 2008支持的数据类型,其主要用于列、参数、变量和用户定义函数的返回值中。当某个字段需要存储不同类型的数据时,可以将其设置为sql_variant类型。table类型是一种特殊的数据类型,用于存储结果集以便于后续的处理。table类型...
public boolean supportsAlterTableWithDropColumn() 傳回值 如果支援,則為true。 否則為false。 例外狀況 SQLServerException 備註 這個supportsAlterTableWithDropColumn 方法是由 java.sql.DatabaseMetaData 介面中的 supportsAlterTableWithDropColumn 方法指定。