索引的匹配方式有哪些?
全值匹配
全值匹配指的是和索引中的所有列進行匹配
explain select * from staffs where name = ‘July’ and age = ‘23’ and pos = ‘dev’;
匹配最左前綴
只匹配前面的幾列
explain select * from staffs where name = ‘July’ and age = ‘23’;
explain select * from staffs where name = ‘July’;
匹配列前綴
可以匹配某一列的值的開頭部分
使用索引: explain select * from staffs where name like ‘J%’;
索引失效:explain select * from staffs where name like ‘%y’;
匹配范圍值
可以查找某一個范圍的數據
explain select * from staffs where name > ‘Mary’;
精確匹配某一列并范圍匹配另外一列
可以查詢第一列的全部和第二列的部分
explain select * from staffs where name = ‘July’ and age > 25;
只訪問索引的查詢
查詢的時候只需要訪問索引,不需要訪問數據行,本質上就是覆蓋索引
explain select name,age,pos from staffs where name = ‘July’ and age = 25 and pos = ‘dev’;
總結
以上是生活随笔為你收集整理的索引的匹配方式有哪些?的全部內容,希望文章能夠幫你解決所遇到的問題。