When data is entered, Access checks to see whether the input breaks a validation rule — if so, the input is not accepted, and Access displays a message. Data types Every table field has a data type that restricts what users can enter.
Field properties Some field properties restrict data input. For example, the Field Size property of a field restricts input by limiting the amount of data. You can also use the Validation Rule property to require specific values, and the Validation Text property to alert your users to any mistakes. Entering text such as "Enter values between and 1," or "Enter an ending date on or after the start date" in the Validation Text property tells users when they have made a mistake and how to fix the error.
Input masks You can use an input mask to validate data by forcing users to enter values in a specific way. For example, an input mask can force users to enter dates in a European format, such as You can use these methods of validating data alone or in combination with each other. Data types are not optional, and provide the most basic type of data validation. For more information about data types, field sizes, and input masks, see the article Introduction to data types and field properties.
Field validation rules Use a field validation rule to check the value that you enter in a field when you leave the field. Your rule now requires users to enter dates on or after January 1, If you enter a date earlier than and then try to place the focus on another field, Access prevents you from leaving the current field until you fix the problem.
Record validation rules Use a record validation rule to control when you can save a record a row in a table. Unlike a field validation rule, a record validation rule refers to other fields in the same table. You create record validation rules when you need to check the values in one field against the values in another.
For example, suppose your business requires you to ship products within 30 days and, if you don't ship within that time, you must refund part of the purchase price to your customer. If the syntax for validation rules looks cryptic, see the section What you can put in a validation rule for an explanation of the syntax and some example validation rules.
You can define validation rules for table fields and for controls on forms. When you define rules for tables, those rules apply when you import data. To add validation rules to a table, you open the table and use commands on the Fields tab of the ribbon.
To add validation rules to a form, you open the form in Layout view and add rules to the properties of individual controls. The steps in the section Add a validation rule to a table explain how to add validation rules to table fields.
The steps in the section Add a validation rule to a control on a form , later in this article, explain how to add rules to the properties in individual controls. Your validation rules can contain expressions — functions that return a single value. You can use an expression to perform calculations, manipulate characters, or test data. A validation rule expression tests data. Expressions can also perform mathematical operations. The expression [OrderDate] - [ShipDate] calculates the number of days that elapsed between the time an order was placed and the time it shipped.
For more information about expressions, see the article Build an expression. Top of Page. A field validation rule checks input to a field, and is applied when the focus leaves the field. A record validation rule checks input to one or more fields is applied when the focus leaves the record. Usually, a record validation rule compares the values of two or more fields. Notes: The following field types do not support validation rules:. Use the Expression Builder to create the rule.
Select the field that needs a message for input that is not valid. The field should already have a validation rule. Enter an appropriate message. For some examples of field validation rules and messages, see the section Validation rule reference. Now you need to choose the field onto which you need to apply field validation. Here in the shown figure, we are applying field validation rule on the column Marks.
Tap to the Fields tab present on the menu bar. After then you will see a field validation box within which a Validation drop-down is present. From the drop-down menu choose the validation rule option to write validation expression. Tapping to that option will open the Expression Builder dialog box. In this, you can write an expression for validating the field entries.
Here we are considering the condition that all the course carries a total of marks but the obtained marks must be lower than So now we will write a simple expression for validating marks field just like shown in the figure. Within the Expression Element, Values, and Categories, there are several expressions present that you can easily apply over the selected field. Tap to the OK option, for applying it successfully. Now we will write a message which will pop-up to clarify the condition that applied above.
For this, you just need to go to the fields tab and from the validation option tap to the Field Validation Message option. Now type a message which you want to display when anyone enters any invalid data. Tap to the OK option to continue. Your entered validation message will pop-up when any invalid data is entered in the table. Thus, this will prevent you from making any data entry errors.
Well, you can make use of Validation Text property and Validation Rule property of the form control for adding validation rule to any form or control. This will ultimately help you to validate input data to that specific control and also restricts the user to insert invalid data. Note: creating a form automatically through the table by using the Form commands present on the menu bar ribbon will set the validation rule for the fields present in that particular table.
Well, a control may have several validation rules for the table fields and for the control that is bound. It is very helpful if anyone wants to set more restrictive rules as compared to the table. Firstly, you need to apply the form rule and after then table rule is to be set. If the access table is much restrictive compared to form then rules which are defined for the table field will get the precedence.
Eg: suppose you are applying following rule into the date field of the table:. But after then you apply the same rule on form control which is bounded to date field:. Now the date field needs values before the year but here your form control needs dates that have a year or after the year Archived Forums. NET Managed Providers. NET managed providers, especially System. SqlClient, System. Odbc and System. Sign in to vote. Thursday, August 30, AM. Friday, August 31, PM.
Thank you for the reply so it's a bad idea to set the validation at the database level I see so i should set validation at the code level Monday, September 3, AM.
That aside, to answer your question I think you have your syntax slightly wrong.
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