Parameters
"ODBC"

Keyword. Indicates that you are accessing an ODBC data source.

Keyword. Optional. If you want to ensure that Notes retrieves the latest information for every lookup, specify this option, as in ODBC:NoCache. Omit "NoCache" if you want the results of the lookup to be cached, that is, stored for re-use by each subsequent lookup to the same location (within the same Notes session and so long as the database executing this lookup remains open).

If you omit NoCache, you do not have to replace it with anythingthe lookup results are cached automatically, but you can specify "Cache" for readability. See "Specifying NoCache."

Text. The name of the external data source being accessed. A data source indicates the location of one or more database tables. See "Specifying the data source."

Text-list. The user IDs needed to connect to the external database. You may need up to two IDs, depending on the DBMS being accessed. See "Specifying IDs and passwords."

Text list. The passwords required by the user IDs. See "Specifying IDs and passwords."

Text. The name of the database table being accessed.

Text. The name of the column from which data is being retrieved.

Text. Specifies how null values are treated when the data is retrieved. See "Specifying null handling."

Text. The name of the column used for key matching.

Text, number, or date-time, or a list. The value to be looked up in key_column.

Keyword. Optional. Removes duplicate values from the list before returning data to Notes. See "Specifying Distinct."

Keyword. Sorts the list of values into either ascending or decending order before it is returned to Notes. See "Specifying sort."

Text, number, date-time, or a list of these types. The values found in the column you indicated. See Accessing the values found, below.

For example, if youre using lookups to a database that stores customer addresses, its generally safe to use caching because you dont expect the addresses to change very often. But if youre using a lookup to a database where stock prices are stored, and that database gets updated hourly, its safer to omit caching and force a new lookup each time.

Note If you use the option button or the check box user interface for a keywords field, Notes updates the keyword list only when the document is composed or opened for editing. If you use the Standard user interface for the list, the keyword list is additionally updated every time the document is recalculated.

@DbLookup can access data sources that have already been registered in the ODBC.INI file (or similar registry on platforms on other than Windows). It can also autoregister a data source not present in the registry. For autoregistration, specify the data source as "data_source" : "type" : "path" where data_source is the name to be assigned, type identifies the DBMS (for example, "Oracle7"), and path is a server name, directory, or other string that locates the DBMS.

Specifying IDs and passwords
You only need these arguments if your DBMS requires them.

Instead of storing the IDs in the @DbLookup formula, you can replace them with null strings (""). If an ID is required, the user will be prompted for it. This is useful when you do not want other designers to see IDs, or when you want users to enter their own IDs when accessing external data. However, you must include IDs and passwords in formulas that will run automatically (such as an agent) because those formulas don't prompt for information.

The user IDs and passwords for accessing a data source are required only once per Notes database session as long as that database remains open. If the user opens another Notes database and executes a formula that accesses the same data source, the user ID and password will be required again.

Password parameters are necessary only when ID parameters are specified. Like IDs, passwords can either be stored in the @DbLookup formula, or prompted for by the ODBC driver by substituting the null string. If the database password is null, you can omit it from the formula.

For example, for the full ID/password specification, enter:

• "";"" (two null strings, separated by a semi-colon) to specify no ID and password, or to prompt for both
• "user_ID1":"password1" to specify one user ID and password combination
• "user_ID1":"user_ID2";"password1":"password2" to specify two user ID and password combinations

For example:

"dbo.author"

Table can also refer to a database view in the DBMS being accessed.

Specifying null handling
To control how null values are handled, specify one of the following, appended to the column parameter with a colon:

• Generates "Fail" this error message if the column of data contains any null values:

No data is returned with the message.
• Discards "Discard" the null values, thus shortening the returned list of values. If one or more values are discarded when the @DbLookup formula is executed, Notes displays this message on the status bar:

• Value "Replacement value" that you specify to be used instead of null values. The replacement value must be a quoted string, but if the column is numeric or date-time, the string must be convertible to that type.

  If your formula includes a sort keyword, the list of values to be returned is sorted before the replacement values are inserted. During sorting, all null values are placed at the beginning of the list for an ascending sort, and at the end for a descending sort. They are not replaced until sorting is complete. This can result in a list that has some values sorted incorrectly. For example, if you specify "zz" as your replacement value, all the "zzz" values will appear at the beginning of the list, even if you sorted it in ascending order.

  If one or more values are replaced when the @DbLookup formula is executed, Notes displays this message on the status bar:

Generally, the replacement value should be one that is not likely to appear in the list as valid data; for example, if the column is text, your replacement value might be "***" so you can easily find those values in Notes.

The key can be any value; if its a string (text) value, enclose it in quotation marks.

Together, the key column and the key form the where clause of a selection statement:

SELECT column WHERE key_column = key

The ODBC Application Interface always tests for equality and only returns data from records where the value in the key column exactly matches the key. To test whether the value in the key column matches one of several possible values, format the key value as a list, separating items with colons as in Red:Blue:Green." This acts like an OR operation, returning data from all records where the value in the key column matches Red OR Blue OR Green." To perform an AND operation or to test for inequality, use @DbCommand to pass the appropriate command string to the DBMS.

Specifying Distinct
The Distinct keyword is similar to @Unique in Notes, except that Distinct ensures that duplicate values are removed before the data is returned to Notes. Using Distinct instead of @Unique has two advantages:

• The formula operates more quickly because the additional work is performed outside of Notes.
• You can potentially retrieve a larger amount of useful data into Notes--since the duplicate values are removed at the back-end, more unique values can be returned to Notes.

Specifying sort
If you use the Distinct keyword, you can append the sort parameter to it with a colon. Use one these keywords for the sort parameter to specify sorting of the return values:

• Ascending sorts the list in ascending order.
• Descending sorts the list in descending order.

Note The sort keywords are not supported by all ODBC drivers. If you attempt to use both Ascending and Descending in your formula, Notes displays an "Invalid argument" message.

Accessing values found

If multiple values are returned, they are formatted as a list and are separated with the multi-value separator designated for the current field.

@DbLookup can return no more than 55K bytes of data. Use the following equations to determine how much of your data can be returned with @DbLookup.

• For lookups that return text:

  2 + (2 * number of entries returned) + total text size of all entries

  Each text string is limited to 511 bytes; if only one text string is returned, it is limited to 55K bytes.

• For lookups that return numbers or dates:

  (10 * number of entries returned) + 6

NoExternalApps=1

the @DbLookup formula is disabled. The user will not see an error message; the formula fails to execute. This applies to @DbLookup only when you use it with ODBC.