Home Database Mysql Tutorial Access入门教程7.6补充内容[1]

Access入门教程7.6补充内容[1]

Jun 07, 2016 pm 04:02 PM
access Getting Started Tutorial content data

补充一 各种数据类型的含义和使用方法 在表的设计视图中 每一个字段都有设计类型 Access允许九种数据类型 文本 备注 数值 日期/时间 货币 自动编号 是/否 OLE对象 超级链接 查询向导 文本 这种类型允许最大 个字符或数字 Access默认的大小是 个字符 而且系统

    补充一各种数据类型的含义和使用方法

    在表的设计视图中每一个字段都有设计类型Access允许九种数据类型文本备注数值日期/时间货币自动编号是/否OLE对象超级链接查询向导

    文本这种类型允许最大个字符或数字Access默认的大小是个字符而且系统只保存输入到字段中的字符而不保存文本字段中未用位置上的空字符可以设置字段大小属性控制可输入的最大字符长度

    备注这种类型用来保存长度较长的文本及数字它允许字段能够存储长达个字符的内容但Access不能对备注字段进行排序或索引却可以对文本字段进行排序和索引在备注字段中虽然可以搜索文本但却不如在有索引的文本字段中搜索得快

    数字这种字段类型可以用来存储进行算术计算的数字数据用户还可以设置字段大小属性定义一个特定的数字类型任何指定为数字数据类型的字型可以设置成字节整数长整数单精度数双精度数同步复制ID小数五种类型在Access中通常默认为双精度数

    日期/时间这种类型是用来存储日期时间或日期时间一起的每个日期/时间字段需要个字节来存储空间

    货币这种类型是数字数据类型的特殊类型等价于具有双精度属性的数字字段类型向货币字段输入数据时不必键入人民币符号和千位处的逗号Access会自动显示人民币符号和逗号并添加两位小数到货币字段当小数部分多于两位时Access会对数据进行四舍五入精确度为小数点左方位数及右方位数

    自动编号这种类型较为特殊每次向表格添加新记录时Access会自动插入唯一顺序或者随机编号即在自动编号字段中指定某一数值自动编号一旦被指定就会永久地与记录连接如果删除了表格中含有自动编号字段的一个记录后Access并不会为表格自动编号字段重新编号当添加某一记录时Access不再使用已被删除的自动编号字段的数值而是重新按递增的规律重新赋值

    是/否这种字段是针对于某一字段中只包含两个不同的可选值而设立的字段通过是/否数据类型的格式特性用户可以对是/否字段进行选择

    OLE对象这个字段是指字段允许单独地链接嵌入OLE对象添加数据到OLE对象字段时可以链接或嵌入Access表中的OLE对象是指在其他使用OLE协议程序创建的对象例如WORD文档EXCEL电子表格图像声音或其他二进制数据OLE对象字段最大可为GB它主要受磁盘空间限制

    超级链接这个字段主要是用来保存超级链接的包含作为超级链接地址的文本或以文本形式存储的字符与数字的组合当单击一个超级链接时WEB浏览器或Access将根据超级链接地址到达指定的目标超级链接最多可包含三部分一是在字段或控件中显示的文本二是到文件或页面的路径三是在文件或页面中的地址在这个字段或控件中插入超级链接地址最简单的方法就是在插入菜单中单击超级链接命令

    查阅向导这个字段类型为用户提供了一个建立字段内容的列表可以在列表中选择所列内容作为添入字段的内容

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