优化SQL语句的一般步骤

where 1=1 and a.customer_id = b.customer_id and email = 'JANE.BENNETT@sakilacustomer.org'\G

*************************** 1. row ***************************

id: 1

select_type: SIMPLE

table: a

partitions: NULL

type: ALL

possible_keys: PRIMARY

key: NULL

key_len: NULL

ref: NULL

rows: 599

filtered: 10.00

Extra: Using where

*************************** 2. row ***************************

id: 1

select_type: SIMPLE

table: b

partitions: NULL

type: ref

possible_keys: idx_fk_customer_id

key: idx_fk_customer_id

key_len: 2

ref: sakila.a.customer_id

rows: 26

filtered: 100.00

Extra: NULL

2 rows in set, 1 warning (0.00 sec)

MySQL [sakila]> show warnings;

+-------+------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

| Level | Code | Message |

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本文标题：优化SQL语句的一般步骤

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