oracle sql优化之多表连接优化

Use equality first.
使用等连接
Use range operators only where equality does not apply.
只有在等连接不可用的情况下事由区间连接
Avoid use of negatives in the form of !=
or NOT.
避免使用 ！= 或者 not
Avoid LIKE pattern matching.
避免使用 LIKE匹配
Try to retrieve specific rows and in small numbers.
尝试查找特殊的列和在小的数目中
Filter from large tables first to reduce rows joined.
Retrieve tables in order from the most highly filtered table downwards;
preferably the largest table has the most filtering applied.
过滤大表减少连接的行数，从过滤多的表向下查找，尽可能的过滤大表
Tip 
The most highly filtered table is the table having the
smallest percentage of its rows retrieved, preferably the largest
table.
Use indexes wherever possible except for very small
tables.
除非很小的表，无论什么情况多有索引
Let the Optimizer do its job.
让优化器做优化