Re: Why not use index

[zhang peng]

This is my sql:
SELECT
*
FROM
crm_order_manual_detail_t AS d,
crm_order_manual_t AS m
LEFT JOIN crm_order_t crm ON m.wp_order_id = crm.source_order_id
OR m.source_order_id = crm.source_order_id
WHERE
d.wp_order_id = m.wp_order_id

Explain result:
1 SIMPLE d ALL PRIMARY 63
1 SIMPLE m eq_ref PRIMARY PRIMARY 62 db_purchase_dev.d.wp_order_id 1
1 SIMPLE crm ALL ix_crm_order_t_source_order_id 86001 Range checked for each record (index map: 0x8)

m.wp_order_id is primary key,crm.source_order_id and m.source_order_id have index