Microsoft access memo field size

Think of a field's data type as a set of qualities that applies to all the values that are contained in the field. For example, values that are stored in a Text field can contain only letters, numbers, and a limited set of punctuation characters, and a Text field can only contain a maximum of characters.

Tip: Sometimes, the data in a field may appear to be one data type, but is actually another. For example, a field may seem to contain numeric values but may actually contain text values, such as room numbers. You can often use an expression to compare or convert values of different data types.

The following tables show you the formats available for each data type and explain the effect of the formatting option.

Short, alphanumeric values, such as a last name or a street address. Note, beginning in Access , Text data types have been renamed to Short Text. Results of a calculation. The calculation must refer to other fields in the same table. You would use the Expression Builder to create the calculation. Note, Calculated fields were first introduced in Access Attached images, spreadsheet files, documents, charts, and other types of supported files to the records in your database, similar to attaching files to e-mail messages.

Long blocks of text. A typical use of a Memo field would be a detailed product description. Note, beginning in Access , Memo data types have been renamed to Long Text. Displays either a list of values that is retrieved from a table or query, or a set of values that you specified when you created the field.

The Lookup Wizard starts and you can create a Lookup field. The data type of a Lookup field is either Text or Number, depending on the choices that you make in the wizard.

Lookup fields have an additional set of field properties, which are located on the Lookup tab in the Field Properties pane. Note: Attachment and Calculated data types aren't available in.

Display the date in a short format. Depends on your regional date and time settings. Display the date in a long format. Depends on you're the regional date and time settings.

Display the time only using a 12 hour format that will respond to changes in the regional date and time settings. Display the time only using a 24 hour format that will respond to changes in the regional date and time settings. After you create a field and set its data type, you can set additional field properties. The field's data type determines which other properties that you can set. For example, you can control the size of a Text field by setting its Field Size property.

For Number and Currency fields, the Field Size property is especially important, because it determines the range of field values. For example, a one-bit Number field can store only integers ranging from 0 to The Field Size property also determines how much disk space each Number field value requires.

Depending on the field size, the number can use exactly 1, 2, 4, 8, 12, or 16 bytes. Note: Text and Memo fields have variable field value sizes.

For these data types, Field Size sets the maximum space available for any one value. For more details about field properties and how they work with the different data types go to the Data type reference section.

Also read the article Set the field size. A table relationship is an association between common fields in two tables.

A relationship can be one-to-one, one-to-many, or many-to-many. A join is a SQL operation that combines data from two sources into one record in a query recordset based on values in a specified field that the sources have in common. A join can be an inner join, a left outer join, or a right outer join. When you create a table relationship or add a join to a query, the fields that you connect must have the same or compatible data types.

For example, you cannot create a join between a Number field and a Text field, even if the values in those fields match. In a relationship or a join, fields that are set to the AutoNumber data type are compatible with fields that are set to the Number data type if the Field Size property of the latter is Long Integer.

You cannot change the data type or the Field Size property of a field that is involved in a table relationship. You can temporarily delete the relationship to change the Field Size property. However, if you change the data type, you won't be able to re-create the relationship without first also changing the data type of the related field.

For more information on tables see the article, Introduction to tables. When you apply a data type to a field, it contains a set of properties that you can select. Click on data types below for more information.

Large Number. OLE Object. Purpose Used in a field that allows attaching files or images to a record. For example, if you have a job contacts database, you can use an attachment field to attach a photo of the contact, or attach documents such as a resume. For some file types, Access compresses each attachment as you add it.

Attachment data types are available only in. You can attach many kinds of files to a record. However, some file types that may pose security risks are blocked.

As a rule, you can attach any file that was created in one of the Microsoft Office programs. You can also attach log files. For a list of supported image file formats, see the table later in this section. The label text that is displayed for this field by default in forms, reports, and queries. If this property is empty, the name of the field is used.

Any text string is allowed. Access supports the following graphic file formats without the need for additional software being installed on your computer. In addition, file names must follow the following guidelines:. Names cannot contain the following characters: question marks? Purpose Use an AutoNumber field to provide a unique value that serves no other purpose than to make each record unique.

The most common use for an AutoNumber field is as a primary key, especially when no suitable natural key a key that is based on a data field is available. An AutoNumber field value requires 4 or 16 bytes, depending on the value of its Field Size property.

Suppose that you have a table that stores contacts' information. You can use contact names as the primary key for that table, but how do you handle two contacts with exactly the same name?

Names are unsuitable natural keys, because they are often not unique. If you use an AutoNumber field, each record is guaranteed to have a unique identifier.

Note: You should not use an AutoNumber field to keep a count of the records in a table. AutoNumber values are not reused, so deleted records can result in gaps in your count. Moreover, an accurate count of records can be easily obtained by using a Totals row in a datasheet. Determines the amount of space that is allocated for each value.

For AutoNumber fields, only two values are allowed:. This is the default value. You should not change this value unless you are creating a replication ID field. Note: Replication is not supported in databases that use a new file format, such as. This setting makes AutoNumber fields compatible with other Long Integer Number fields when they are used in relationships or joins.

Each field value requires 4 bytes of storage. Do not use this value unless you are working in or implementing the design of a replicated database. Determines whether AutoNumber field increments with each new value or uses random numbers.

Select one of the following:. Increment Starts with the value 1 and incrementally increases by 1 for each new record. Random Starts with a random value and assigns a random value to each new record. Values are of the Long Integer field size, and range from -2,,, to 2,,, If you are using an AutoNumber field as a primary key or as a Replication ID, you should not set this property. Also, it appears that some of the issues with Memo field corruption have been fixed: memo-fields-multiuser-database also of note is that markwillium's post even echos information found within this thread.

I'm sure that the site admins have started a review of this post. I have used memo fields in my databases since I started developing in Access, and I have to say I don't really agree with the contents of your post.

It makes perfect sense actually to restrict the query engine to not work on the entire field, especially since memo fields can in theory contain over a hundred thousand characters although max limit on GUI is Know your tool.

Perhaps Memo fields are more susceptible then other types of fields to corruption. I am also more likely to be in a accident if I use my car rather then walk, all the same I still use my car, and I still use my memo fields. That said, you should of course not use a memo field to store text that you know will never be longer then characters. Don't use a memo field for a first name.

This is no different then I shouldn't use a text field to store an integer even though possible , and I shouldn't store dates in a text field either. Taneer I believe the main purpose of this post was to sneak in a link commercial spam to a site. The link was removed by Rabbit, and I will leave the post as is.

People are entitled to their opinions on Memo fields, but I don't really believe this counts as an insight. In general if you keep your frontend seperated from your backend, and avoid doing design changes on a live database the risks of corruption are small. Make sure you have a backup strategy. Make sure that your local IT department takes regular backups, of the backend file. In 5 years of developing I have twice had the need to retrieve a backup file.

One was caused by yours truly running a bad update query wooops and the other was caused by a complete power failure to the network drive. Post Reply. How can error messages be displayed when using Command Buttons - Access 97? Memo Fields. Word truncates Memo field when using Automation from Access. Visual Basic. You can change the field size of a field that is empty or that already contains data. The effect of changing the field size depends on whether the field already contains data.

If the field does not contain data When you change the field size, the size of new data values is limited for the field. For number fields, the field size determines exactly how much disk space Access uses for each value of the field. For text fields, the field size determines the maximum amount of disk space that Access allows for each value of the field.

If the field contains data When you change the field size, Access truncates all the values in the field that exceed the specified field size, and also limits the size of new data values for the field, as described above. Tip: If the field for which you want to change the field size already contains data, consider making a backup of your database before you proceed.

In the Navigation Pane, right-click the table that contains the field that you want to change, and then click Design View.

In the Field Properties pane, on the General tab, enter the new field size in the Field Size property. You can choose from the following values:. Byte — For integers that range from 0 to Storage requirement is a single byte.

Storage requirement is two bytes. Storage requirement is four bytes. Tip: Use the Long Integer data type when you create a foreign key to relate a field to another table's AutoNumber primary key field. Single — For numeric floating point values that range from Double — For numeric floating point values that range from Storage requirement is eight bytes. Storage requirement is 16 bytes.