Dear Daniel, the younger brother novice, want to ask a few questions:

1. If I use

 select * from where the primary key Id in () 

the explain found using range, and use the

 select * from where the primary key index but also in () 

the explain and use the range, the two efficiency gap in where? Efficiency difference big?

2. If I use a for loop, each loop using the

 select * from where the primary key Id=

if you don't use cycle,

 select * from where the primary key Id in () 

the efficiency of the two methods, is there a difference?

Thank please Daniel can guidance to us

CodePudding user response:

More than 1 of the primary key index step back to fetch the data table

2 use a for loop increasing network consumption, with higher in efficiency

CodePudding user response:

1. The primary key index is certainly no primary key index of high efficiency
2. High efficiency than the for loop in