Example tutorial on processing special sql statements in mysql

The following editor will bring you a summary of the special processing statements of mysql's sql statements (must read). The editor thinks it’s pretty good, so I’ll share it with you now and give it as a reference. Let’s follow the editor and take a look.

1. Update the entire table. If the value of a column in a row of data is empty, then let it and another The values ​​of a column of fields are equal

UPDATE ot_tgbz set update_day=if(update_day is null,date,update_day);

2,Update the entire table, if a field is greater than 2, then update them all to 2;

UPDATE ot_user set xingyun_num=if(xingyun_num > 2,2,xingyun_num);

3, Replace all URLs containing http://www.jb51.net/ in the thumb field in the shop_goods table with empty ones.

update shop_goods  set thumb= replace (thumb,'http://www.jb51.net/','') where thumb like '%http://www.jb51.net/%';

4、sql statement multi-field wherequery

$map= " CAST(
  `UE_account` AS CHAR CHARACTER
     SET utf8
  ) LIKE '%$data%'
  OR CAST(
    `UE_accName` AS CHAR CHARACTER
    SET utf8
  ) LIKE '%$data%'
  OR CAST(
    `UE_truename` AS CHAR CHARACTER
    SET utf8
  ) LIKE '%$data%'
  OR CAST(
    `UE_phone` AS CHAR CHARACTER
    SET utf8
  ) LIKE '%$data%'";

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