Fmdb deadlock Problem

Using Fmdb for database operations, there is a crash error such as Indatabase:was called reentrantly on the same queue, which would leads to a deadlock . The reason is that in a A [queue indatabase] block, another indatabase is executed. The first block needs to be completed before it can be queued and the second block can be executed. But the first block contains the second block, In other words, the second block does not execute, and the first block cannot be ended. So they wait for each other, which is a variety of deadlocks

Fmdb deadlock Problem