Two methods of covering duplicate records in tables in MySQL

replace into The way

Prerequisite

There must be a primary key or unique index in the table .

principle

Find data with the same primary key according to the primary key or unique index , Then delete the original data , Add new data .

If there is no same primary key or unique index in the table , It's equivalent to insert into.

Use cases

# topic、partition、groupid It's the primary key 
replace into t_offset (`topic`, `partition`, `groupid`, `offset`) values(?,?,?,?)")

ON DUPLICATE KEY UPDATE The way

Prerequisite

There must be a primary key or unique index in the table .

principle

Find data with the same primary key according to the primary key or unique index , And then execute update update operation .

If there is no same primary key or unique index in the table , It's equivalent to insert into.

Use cases

# userid It's the primary key 
insert into black_list(userid) value (?)
on DUPLICATE KEY
UPDATE userid = ?