Re: Indexes

In article <5dvppk$77q@cssun.mathcs.emory.edu>, Susik Lee <susikl@skechers.com> writes >If I have following table: > table A customer char(10), > inv_num int, > bill_data date, > ship_date date, > bill_amt real, > print_flag char(1) > > cust_index on (customer) > cust_index2 on (customer, inv_num) > cust_index3 on (bill_date) > >Question 1: > select count(*) from A where customer = "1111" and print_flag <> "A"> > How does on-line search table A? Will it get all the records from >table A where customer = "1111" using index, than search records base on >print_flag within these records? For example: We have 200,000 records in Yes, it reads down the levels of the index and then along the list of rows wiht the same index keys. >table A and 50 records with customer = "1111". Will the above select >statement will get 50 records from table than search base on print_flag on >these 50 records only?. > >Question 2: > select count(*) from A where customer = "1111" and bill_date = "10/1/96"> > Will about sql will use cust_index and cust_index3 to get records? >Or do I need to create new index on (customer, bill_date)? Create a new index. > >Thanks > >----- > Susik Lee > Skechers USA > email: susikl@skechers.com > phone: (310) 318-3100x1285 > -- David Williams