Query Questions

-


 

Comments

Post a Comment

Popular posts from this blog

Window Function

-
 Categories of widow function 1. Aggregated fun : avg, sum , max, min , count 2. Ranking func :  Rank, dense_rank, row_number 3. Analytical func : Lead, Lag, first_value, last_value Lag : Return previous row and depends on offset LAG ( expression [, offset [, default] ] ) OVER ( [ query_partition_clause ] order_by_clause ) Lead : Return next row and depends on offset. LEAD( expression [, offset [, default] ] ) OVER ( [ query_partition_clause ] order_by_clause )
Read more

Materialized View

-
 It is a database object. It is different from normal view. View doesn't contain any data in it whereas MV contains data in it. We create MV for remote database object in our local db.
Read more

Sequence

-
Generate Unique Sequential values     Sequence has 2 pseudocolumns     1. CURRVAL     2. NEXTVAL CURRVAL :  gives the most recently generated value NEXTVAL : gives the next available value in the sequence to generate sequence will start generating value from its MINVALUE Default MINVALUE is 1 default incremental value of sequence is +1 Same sequence can be used in multiple tables but not suggestable. One sequence for one table.
Read more