mysql Like查詢使用索引的情況
阿新 • • 發佈:2018-12-04
EXPLAIN SELECT *FROM `hb_send_list` WHERE hongbao_id LIKE '%AA1317B32755BDFC1B8036'
id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
1 | SIMPLE | hb_send_list | ALL | (NULL) | (NULL) | (NULL) | (NULL) | 14382 | Using where |
EXPLAIN SELECT *FROM `hb_send_list` WHERE hongbao_id LIKE 'AA1317B32755BDFC1B8036%'
id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
1 | SIMPLE | hb_send_list | range | hongbao_id | hongbao_id | 98 | (NULL) | 1 | Using index condition |
EXPLAIN SELECT *FROM `hb_send_list` WHERE hongbao_id LIKE 'A%A1317B32755BDFC1B8036'
id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
1 | SIMPLE | hb_send_list | range | hongbao_id | hongbao_id | 98 | (NULL) | 995 | Using index condition |
mysql在使用like查詢,%在最前面不會用到索引,中間或最後是會用到索引的,只是越靠前掃描的行數越多