Error getting tags :
error 404Error getting tags :
error 404 revDatabaseColumnIsNull | revDocs | RunRev
Welcome Guest (Log in)
Product Edition
Version
revDatabaseColumnIsNull
Basics
Expander triangle
Type
Function
Syntax

revDatabaseColumnIsNull(recordSetID,columnNumber)

Introduced
1.1.1
Changed
2.0
Environment
Desktop, Web and Server
Platform Support
MacOS,Mac OS X,Windows,Linux
Security
Disk,Network
Summary
Returns true if the specified database field has a null value, false otherwise.
Examples

revDatabaseColumnIsNull(currentResults,the number of items in myString)
repeat while revDatabaseColumnIsNull(12,3) -- is field 3 null?

Additional Comments
Expander triangle

Use the revDatabaseColumnIsNull function to find out whether one of the database fields in the current record is set to a value.

Parameters:

The recordSetID is the number returned by the revQueryDatabase function when the record set (database cursor) was created.

The columnNumber is the number of the column.

Value:

The revDatabaseColumnIsNull function returns true or false.

Comments:

A null value in a SQL database refers to a value that is unknown or not applicable. For example, if the price of an item in a product database has not yet been determined, its "Price" field is typically set to null. The null value is not zero: the item's price is not zero, but undetermined.

The special null value allows the database to differentiate between an unknown value deliberately inserted, and a value of zero or a blank field.

This means that if the data value of the database field is empty or zero, the revDatabaseColumnIsNull function returns false. It only returns true if the field's value is not set at all.

Important! The revDatabaseColumnIsNull function is part of the Database library. To ensure that the function works in a standalone application, you must include this custom library when you create your standalone. In the Inclusions section of the General screen of the Standalone Application Settings window, make sure the "Database Support" checkbox is checked and the database drivers you are using are selected in the list of database drivers.

Changes to Revolution:

The revDatabaseColumnIsNull synonym was added in version 2.0.

User Comments
Expander triangle