How to Check if value exists in a MySQL database

Question

Suppose I have this table   id   name   city ------------------ 1    n1     c1 2    n2     c2 3    n3     c3 4    n4     c4   I want to check if the value c7 exists under the variable city or not     If it does  I will do something  If it doesn t  I will do something else

User · Answer

For Exact Match   SELECT   FROM yourTable WHERE city    c7     For Pattern   Wildcard Search   SELECT   FROM yourTable WHERE city LIKE   c7      Of course you can change   c7   to   c7  or  c7   depending on how you want to search it  For exact match  use first query example   PHP   result   mysql query  SELECT   FROM yourTable WHERE city    c7      matchFound   mysql num rows  result   gt  0    yes     no   echo  matchFound    You can also use if condition there

User · Answer

This works for me     db   mysqli connect  localhost    UserName    Password    DB Name   or die  Not Connected    mysqli set charset  db   utf8      sql   mysqli query  db  quot SELECT   FROM  mytable  WHERE city  c7  quot     sql   mysqli fetch assoc  sql    Checker    sql  city     if    Checker    null             echo  Already exists          else        echo  Not found

User · Answer

SELECT     IF city  C7      THEN city     ELSE  somethingelse      END as  city  FROM  table  WHERE  city     c7

User · Answer

I tried to d this for a while and       sqlcommand    SELECT   FROM database WHERE search     searchString            sth    db- gt prepare  sqlcommand        sth- gt execute         record    sth- gt fetch        if   sth- gt fetchColumn    gt  0    just works if there are TWO identical entries  but   if you replace      if   sth- gt fetchColumn    gt  0    with     if   result    it works with only one matching record  hope this helps

User · Answer

For Matching the ID   Select   from table name where 1 1   For Matching the Pattern   Select   from table name column name Like   string

User · Answer

preferred way  using MySQLi extension    mysqli   new mysqli SERVER  DBUSER  DBPASS  DATABASE    result    mysqli- gt query  SELECT id FROM mytable WHERE city    c7     if  result- gt num rows    0            row not found  do stuff      else          do other stuff       mysqli- gt close      deprecated    result   mysql query  SELECT id FROM mytable WHERE city    c7     if mysql num rows  result     0            row not found  do stuff      else          do other stuff

User · Answer

Assuming the connection is established and is available in global scope     Check if a value exists in a table function record exists   table   column   value        global  connection       query    SELECT   FROM   table  WHERE   column      value         result   mysql query    query   connection        if   mysql num rows    result               return TRUE        else           return FALSE            Usage  Assuming that the value to be checked is stored in the variable  username   if  record exists    employee    username    username         echo  Username is not available  Try something else      else       echo  Username is available

[php] How to Check if value exists in a MySQL database

For Exact Match

For Pattern / Wildcard Search

PHP

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