mysql 查看表锁级别

SHOW ENGINE INNODB STATUS;

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LATEST DETECTED FAILURE
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...

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TRANSACTIONS
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Trx id counter 1073741825
Purge done for trx's n:o < 1073741824 undo n:o < 0 state: running but idle
History list length 0
LIST OF TRANSACTIONS FOR EACH SESSION:
---TRANSACTION 0, not started, process no 1151, OS thread id 1150627360
MySQL thread id 42, query id 57 localhost root
show engine innodb status
---TRANSACTION 1073741824, ACTIVE 0 sec, process no 1151, OS thread id 1150617248 starting index read
mysql tables in use 1, locked 1
LOCK WAIT 2 lock struct(s), heap size 368, 1 row lock(s)
MySQL thread id 41, query id 56 localhost root Sending data
select * from t where id=1 lock in share mode
------- TRX HAS BEEN WAITING 0 SEC FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 0 page no 3 n bits 72 index `PRIMARY` of table `test`.`t` trx id 1073741824 lock_mode X waiting
...

CREATE TABLE t (
    id INT PRIMARY KEY,
    name VARCHAR(255)
);

SELECT * FROM t WHERE id = 1 FOR UPDATE;

SELECT * FROM t WHERE id = 1 LOCK IN SHARE MODE;