HTTP CODES 100-101

100
Continue
Tells the client that the first part of the request has been received and that it should continue with the rest of the request or ignore if the request has been fulfilled.

101
Switching Protocols
Tells the client that the server will switch protocols to that specified in the Upgrade message header field during the current [...]

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When MySQL uses indexes
Using >, >=, =, <, <=, IF NULL and BETWEEN on a key.
SELECT * FROM `table_name` WHERE `key_part1` = 1 AND `key_part2` > 5;
SELECT * FROM `table_name` WHERE `key_part1` IS NULL;
When you use a LIKE that doesn’t start with a wildcard.
SELECT * FROM `table_name` WHERE `key_part1` LIKE ‘jani%’
Retrieving rows from [...]

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