InnoDB在不同隔离级别下的一致性读级锁的差异
锁和多版本数据是InnoDB实现一致性读和ISO/ANIS SQL92隔离级别的手段，因此，在不同的隔离级别下，InnoDB处理SQL时采用的一致性读策略和需要的锁是不同的。（下面的表来自《深入浅出MYSQL》20.3.7节）
| SQL | 条件 | Read Uncommitted | Read Committed | Repeatable Read | Serializable |
| select | 相等 | None locks | Consistenread/None lock | Consistenread/None lock | Share locks |
| 范围 | None locks | Consistenread/None lock | Consistenread/None lock | Share Next-key | |
| update | 相等 | exclusive locks | exclusive locks | exclusive locks | exclusive locks |
| 范围 | exclusive next-key | exclusive next-key | exclusive next-key | exclusive next-key | |
| insert | N/A | exclusive locks | exclusive locks | exclusive locks | exclusive locks |
| replace | 无键冲突 | exclusive locks | exclusive locks | exclusive locks | exclusive locks |
| 键冲突 | exclusive next-key | exclusive next-key | exclusive next-key | exclusive next-key | |
| delete | 相等 | exclusive locks | exclusive locks | exclusive locks | exclusive locks |
| 范围 | exclusive next-key | exclusive next-key | exclusive next-key | exclusive next-key | |
| select ... from ... lock in share mode | 相等 | Share locks | Share locks | Share locks | Share locks |
| 范围 | Share locks | Share locks | Share Next-key | Share Next-key | |
| select...from... for update | 相等 | exclusive locks | exclusive locks | exclusive locks | exclusive locks |
| 范围 | exclusive locks | exclusive locks | exclusive next-key | exclusive next-key | |
| insert into...select...（指源表锁） | innodb_locks_unsafe_for_binlog=0 | share next-key | share next-key | share next-key | share next-key |
| innodb_locks_unsafe_for_binlog=1 | None locks | Consistenread/None lock | Consistenread/None lock | Share next-key | |
| create table... select ... （指源表锁） | innodb_locks_unsafe_for_binlog=0 | Share next-key | Share next-key | Share next-key | Share next-key |
| innodb_locks_unsafe_for_binlog=1 | None locks | Consistenread/None lock | Consistenread/None lock | Share next-key |