ODBC and JDBC Developer’s Guide

32 FileMaker ODBC and JDBC Developer’s Guide
Creating an index for any column automatically selects the Storage Option of Automatically create indexes
as needed
in Indexing for the corresponding field in the FileMaker database file.
Example
CREATE INDEX myIndex ON Salespeople.Salesperson_ID
DROP INDEX statement
Use the DROP INDEX statement to remove an index from a database file. The format of the DROP INDEX
statement is:
DROP INDEX [ON] table_name.column_name
Remove an index when your database file is too large, or you don’t often use a field in queries.
If your queries are experiencing poor performance, and you’re working with an extremely large FileMaker
database file with many indexed text fields, consider dropping the indexes from some fields. Also consider
dropping the indexes from fields that you rarely use in SELECT statements.
Dropping an index for any column automatically selects the Storage Option of None and clears Automatically
create indexes as needed
in Indexing for the corresponding field in the FileMaker database file.
The PREVENT INDEX CREATION attribute is not supported.
Example
DROP INDEX ON Salespeople.Salesperson_ID
FROM clause
The FROM clause indicates the tables that will be used in the SELECT statement. The format is:
FROM table_names [table_alias]
table_names can be one or more simple table names in the current working directory or complete
pathnames.
table_alias can be used to give the table a more descriptive name, or to abbreviate a longer table name.
Field names can be prefixed with the table name or the table alias. For example, given the table specification
FROM employee E, you can refer to the LAST_NAME field as E.LAST_NAME. Table aliases must be
used if the SELECT statement joins a table to itself. For example:
SELECT * FROM employee E, employee F WHERE E.manager_id = F.employee_id
The equal sign (=) includes only matching rows in the results.
If you are joining more than one table, and you want to discard all rows that don’t have corresponding rows
in both source tables, you can use INNER JOIN. For example:
SELECT *
FROM Salespeople INNER JOIN Sales_Data
ON Salespeople.Salesperson_ID = Sales_Data.Salesperson_ID
Note OUTER JOIN is not currently supported.