ACCESS数据库的一个表(mytable),有个字段(s_name),该字段之前有个属性:允许空字符串,
我设为否,现在要改成允许空字符串
另外要在该表中加一个字段名(s_address),文本类型,允许空字符串,大小20
请问用Delphi语句怎么实现?
我设为否,现在要改成允许空字符串
另外要在该表中加一个字段名(s_address),文本类型,允许空字符串,大小20
请问用Delphi语句怎么实现?
解决方案 »
- 用clientdataset更新多表联合查询的问题
- 如何判断本地机器是否已连上了互连网?
- 奇怪~~我的专家分为什么没有加上去?
- FastReport或ReportMachine 如何实现即打即停功能,请给出源码。感激!
- 怎样让系统等待?微秒级别的,不是毫秒。
- 请问在DELPHI 7里面怎样做报表
- 象QQ那种我的好友,陌生人,黑名单下拉菜单是什么组件?
- 本人朱小军,专门发帖子说有好东东,但是呢,每次都失信,各位,不要再相信我了。进来投一票吧。
- 谁知道dbgrid加载纪录集是怎么做的呢
- 试用DELPHI6,BUG太多了!
- 做点小贡献,我写的使用二分查找的DataSetLocateEx数.
- 如何销售自己做的软件?大家都是怎么卖自己的软件的?
adoquery1.execsql;
更精确的说明查找SQL帮助,尤其是JET的SQL帮助关于ALTER TABLE部分
adoquery1.execsql;
这段不就可以解决吗?
ALTER TABLE
通过更改、添加、除去列和约束,或者通过启用或禁用约束和触发器来更改表的定义。语法
ALTER TABLE table
{ [ ALTER COLUMN column_name
{ new_data_type [ ( precision [ , scale ] ) ]
[ COLLATE < collation_name > ]
[ NULL | NOT NULL ]
| {ADD | DROP } ROWGUIDCOL }
]
| ADD
{ [ < column_definition > ]
| column_name AS computed_column_expression
} [ ,...n ]
| [ WITH CHECK | WITH NOCHECK ] ADD
{ < table_constraint > } [ ,...n ]
| DROP
{ [ CONSTRAINT ] constraint_name
| COLUMN column } [ ,...n ]
| { CHECK | NOCHECK } CONSTRAINT
{ ALL | constraint_name [ ,...n ] }
| { ENABLE | DISABLE } TRIGGER
{ ALL | trigger_name [ ,...n ] }
}< column_definition > ::=
{ column_name data_type }
[ [ DEFAULT constant_expression ] [ WITH VALUES ]
| [ IDENTITY [ ( seed , increment ) [ NOT FOR REPLICATION ] ] ]
]
[ ROWGUIDCOL ]
[ COLLATE < collation_name > ]
[ < column_constraint > ] [ ...n ]< column_constraint > ::=
[ CONSTRAINT constraint_name ]
{ [ NULL | NOT NULL ]
| [ { PRIMARY KEY | UNIQUE }
[ CLUSTERED | NONCLUSTERED ]
[ WITH FILLFACTOR = fillfactor ]
[ ON { filegroup | DEFAULT } ]
]
| [ [ FOREIGN KEY ]
REFERENCES ref_table [ ( ref_column ) ]
[ ON DELETE { CASCADE | NO ACTION } ]
[ ON UPDATE { CASCADE | NO ACTION } ]
[ NOT FOR REPLICATION ]
]
| CHECK [ NOT FOR REPLICATION ]
( logical_expression )
}< table_constraint > ::=
[ CONSTRAINT constraint_name ]
{ [ { PRIMARY KEY | UNIQUE }
[ CLUSTERED | NONCLUSTERED ]
{ ( column [ ,...n ] ) }
[ WITH FILLFACTOR = fillfactor ]
[ ON { filegroup | DEFAULT } ]
]
| FOREIGN KEY
[ ( column [ ,...n ] ) ]
REFERENCES ref_table [ ( ref_column [ ,...n ] ) ]
[ ON DELETE { CASCADE | NO ACTION } ]
[ ON UPDATE { CASCADE | NO ACTION } ]
[ NOT FOR REPLICATION ]
| DEFAULT constant_expression
[ FOR column ] [ WITH VALUES ]
| CHECK [ NOT FOR REPLICATION ]
( search_conditions )
}