Optimization issues in Oracle

1. When querying, use the name of the column as much as possible;

2. When the sub-query and multi-table query can achieve the goal, try to use multi-table query;

3. In a set operation, if the collection contains null, it cannot be in, but can be used in (which can be understood as null contains all);

Parsing principles for 4.SQL statements: parsing from right to left (SQL execution plan);

5. When using the having and where for conditional filtering, try to use where

6. When the Union and union all are available, the union all should be used;

7. Do not use set operations as much as possible.

Optimization issues in Oracle