Examples of using the or statement in MySQL

1. The use of or syntax in MySQL, and the points to note when using or in MySQL syntax. The project encountered a pitfall, and there was an error in querying the reward data! ! !

$sql = 'SELECT 
        * 
      FROM 
        `vvt_spread_doubleegg_exchange_award` AS p
      WHERE
        p.`act_type` = 4 or p.`act_type` = 5
      AND
        p.`user_id` = ' .$user_id
      ;

The or syntax in sql is generally used for queries with multiple conditions. The above syntax query is equivalent to: the data sets obtained by two sql queries.

 $sql = 'SELECT * FROM `vvt_spread_doubleegg_exchange_award` AS p WHERE p.`act_type` = 4;
 $sql = 'SELECT * FROM `vvt_spread_doubleegg_exchange_award` AS p WHERE p.`act_type` = 5 AND p.`user_id` = ' .$user_id;

2. To query the data set where act_type = 4 and user_id = 11123 or p.`act_type` = 5 and user_id = 11123, you must add () to the conditions on both sides of the or.

$sql = 'SELECT 
        * 
      FROM 
        `vvt_spread_doubleegg_exchange_award` AS p
      WHERE
        (p.`act_type` = 4 or p.`act_type` = 5)
      AND
        p.`user_id` = ' .$user_id
      ;

Summarize

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