![]() * select#1 */ select `example`.`USERS`.`ID` AS `ID` | 2 | DEPENDENT SUBQUERY | EVENTS | NULL | ref | EVENTS_USER_IDX | EVENTS_USER_IDX | 5 | | 97 | 10.00 | Using where | | 2 | DEPENDENT SUBQUERY | EVENTS | NULL | index_subquery | EVENTS_USER_IDX | EVENTS_USER_IDX | 5 | func | 195 | 10.00 | Using where | | 1 | PRIMARY | USERS | NULL | range | PRIMARY | PRIMARY | 4 | NULL | 5 | 100.00 | Using where Using index | | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra | The latter is arguably simpler to write and makes the create table USERSĬreate index EVENTS_USER_IDX on EVENTS(USER_ID) When you want to perform a difference operation between two tables, you have a choice: NOT EXISTS with a correlated subquery, or NOT IN. MySQL: When NOT IN Is Not Equal to NOT EXISTS "NOT EXISTS from derived UNION table" ET: 27920 ms WHERE tbl.filterValue_val = tbl_IN_VS_AND.filterCriterion_sv ) "derived UNION table LEFT OUTER JOIN" ET: 34360 ms ON tbl_IN_VS_AND.filterCriterion_sv = tbl.filterValue_val |-Compute Scalar(DEFINE:(=CONVERT_IMPLICIT(int,0))) ![]() PRINT 'Populating sample table (1.000.000 rows. ![]() (filterCriterion_sv int identity(1,1) PRIMARY KEY CLUSTERED NOT NULL) It places the integer values into a UNION query and does a LEFT OUTER JOIN against that to filter out s.Status_SV 214 The first alternative technique doesn't use a WHERE clause to filter out our integer values. This query is a part of the larger query and I am not using SELECT * I just mentioned it for simplification and id is not nullable. Your use of SELECT * is likely to have a greater negative impact on performance than whether you use IN or EXISTS. ![]() This is why we typically ask for sample data and desired results. #Mysql not equal how to#
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