Data types in Microsoft Access Databases consist of tables, tables consist of fields and fields are of a certain data type. A field's data type determines what kind of data it can hold. Every database has data types for text, integers (integers are whole numbers, i.e. Numbers without a fraction) and decimal numbers and so does Access.
The property that defines a field's maximum storage size for text, number, and AutoNumber fields. Access for Office 365 Access 2019 Access 2016 Access 2013 Access 2010 Access 2007 More. Less You can adjust the amount of space that each record in an Access table uses by changing the field size property of number fields in the table.
But Access also has some data types that are specific to Access, like the Hyperlink, Attachment and Calculated data type. In this article I will describe the Access data types and give an explanation of their use. Choosing data types for your fields When you create tables in Design View, Access lets you choose data types for your fields. you can access Design View by right clicking your table in the object list on the left of the screen and choosing Design View. A field of type Number must contain numbers.
If you try to put in text, Access won't like it and it will let you know. Overview of Access data types When you start using Access it is sometimes difficult to figure out what data type to use for a field. The table below gives you a general description of each data type in Access and situations where you would use the data type.
Access data type Used for Short (. Properties for the Text field The most important properties of the Text are below. Property Explanation Field Size The maximum number of characters you can enter. The largest maximum you can set is 255. Format Rules for the display of this field in the datasheet Input mask In is a pattern that all data entered in this field must adhere to Caption When a caption text is entered, it is displayed as a field label in forms. If nothing is filled out, the filed name is used for this purpose. Default value The is inserted by Access automatically when no other value is supplied for the field.
Validation rule A rule that validates the input. Read more on validation rules in the. Required Indicated whether a value is for this field. Access will show an error message and won't insert the new record if you try to insert a new record that has no value for a required field. Allow Zero Length Indicates whether you are allowed to insert a text that contains zero characters. Indexed Apply an index when you want to allow for fast searching on the field's contents or when you want to impose a unique constraint (Select 'Yes, no duplicates') on the field. The Memo data type The Memo data type is meant to hold text data, just like the Text data type.
In contrast to the Text data type, Memo doesn't have a 255 character size limit. The Memo data type can hold somewhere around 65000 characters if you enter them through the Access interface and 1 Gigabytes if you enter the text programatically. In Access 2007 and 2010, fields of the Memo data type can be configured to contain Rich Text. Rich Text is text to which formatting like bold and italic can be applied.
In the background Access converts this styling to HTML. The properties of the Memo data type are very similar to the field properties of the Text data type, so I won't describe them again. The Text Format property lets you choose between Plain Text and Rich Text. The Number data type The Number data type in Access is a data type for different types of numbers, like Integer, Long Integer, Byte, Decimal, et cetera. The exact number type is configured using the Field Size property. When creating a new Number field the Field Size property defaults to Long Integer. So by default, the Number field can contain whole numbers.
The Field Size property of the Number data type lets you choose a number type for the field. Below are the characteristics of each type.
Field Size Explanation Precision Byte A Byte field allows whole numbers from 0 to 255. Integer The Integer field stores whole numbers between -32.768 and 32.767.
Long Integer The Long Integer field stores whole numbers between -2.147.483.648 and -2.147.483.647. Decimal The Decimal field is used for storing decimal values. It has the largest precision of all Number fields.
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The properties of the Decimal field will let you choose the total precision (max 28) and the number of decimal places. 28 Single For numeric floating point values that range from -3.4 x 10 38 to +3.4 x 10 38. The Single data type has a precision of 7 and is best not used for calculations that require a high level of precision. 7 Double The Double data type stores numbers between -1.797 x 10 308 to +1.797 x 10 308 12 Replication ID A replication ID is a long alphanumeric string that is used in database replication.
The most common Field Size values are probably Long Integer and Double. The Date/Time data type The Date/Time data type is used to store date values, time values, or combined date and time values. In the background Access always stores the date and time you enter like a number. Thedate format you specify determines what part of the date and time is shown in the Access data sheet. In the field properties of a Date/Time field you can pick a format for your date field.
Note that what appears in the Format select list is dependent on your computer's region and language settings. The default date format in Windows on my computer is set to Dutch.
That is why the Long date format is 'dinsdag 19 juni' (tuesday, june 19th). Access will automatically show the date formats that are common to the region and language your computer is set to. If you are not happy with the default date formats that Access offers you can also type in your own custom date format. To learn more about creating your own date format, look. One other nice feature of the Date/Time data type is the Show Date Picker property. When enabled(by selecting 'For dates') Access will show a date picker in the data sheet when a date cell is selected.