Mysql check for last entry in table while inserting

问题

I have a table which has 2 columns Action_key (which stores loggedin and optin values) and Value (which stores 0 or 1)

My table has Id column auto increment.

Update

Below is how im inserting by checking the condition.

Now i need the condition to check if the newly inserting row has same value as the last record's Uid, Action_key and Value, else it should insert.

 $uniquedataoptininArray = array(   //except CreatedDate
        'Uid'=> $uid,
        'Action_key'=> $actionkey,
        'Value'=>$login_optin_value
        );
$userexists=  $this->getUserOptInLogTable()->getOptinLogindetails($uniquedataoptininArray);

if($userexists){

         echo 'record exist';

     }else{
          echo 'To be inserted';
          $result =  $this->getUserOptInLogTable()->insertdetails($dataArray);

The below query gives me the last inserted row - Which is fine. but need to know how i can check the condition using rhe below query

$qry ="SELECT * FROM UserOptInLog WHERE Uid = ". $uid ." ORDER BY Id DESC LIMIT 1;";

Current problem.

Conditions when it should insert

1) If my below table is filled with values like shown, now im trying to insert a row with Uid 1608, ActionKey loggedin and Value 1, but it is not inserting.

2) Or if i make an entry with values Uid 1608, Action_key optin and value 1 - it is not inserting (which should insert ideally)

Conditions when it should not insert

1) with the tables existing data- if i insert Uid 1608, ActionKey loggedin and value 0 - basically the same row as last row - it should not insert

回答1:

If you already have last id from $this->tableGateway->getLastInsertValue() and Action_key & value as "logged_in" & 0 respectively, then there is no need to be concerned about your query...

1. Just check for a record where these 3 items (columns) match:

   SELECT * FROM `table` 
   WHERE `id` = <last_id>    # one you get from $this->tableGateway->getLastInsertValue()
   AND `Action_key` = 'loged_in'
   AND `value` = 0
   

2. Check for the number of records returned from above query:

   • if it returns null, INSERT your new record
   • else, Just Ignore

---

UPDATE

1. Just check for the Uid where these 3 items (columns) match:

   SELECT Uid FROM `table`   # get just Uid column
   WHERE `id` = <last_id>    # one you get from $this->tableGateway->getLastInsertValue()
   AND `Action_key` = 'loged_in'
   AND `value` = 0
   

2. Match the Uid returned from above query:

   • if it doesn't match the new Uid (the record that is going to be inserted), INSERT your new record
   • else, Just Ignore

---

ALSO

You can check for the last value for Uid:

SELECT Action_key, value FROM table
WHERE Uid = uid 
ORDER BY id DESC LIMIT 1;

this will return the last item for the target Uid. Then you can match the Action_key and value columns for matching records...

回答2:

You may use such a statement with subquery

insert into tab
select q.* 
  from  
  (
  select *
    from tab
   where date_ = ( select max(date_) from tab where Action_key = 'loggedin' )
     and Value = 0
  ) q   
where date_ is not null;

来源：https://stackoverflow.com/questions/53313411/mysql-check-for-last-entry-in-table-while-inserting