php - SQLite update is replacing fields with null values -

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okay ive been reading on , working sqlite (someone on here suggested actually).

it works great need - in-memory database. problem having duplicate records in here wanted insert record if exists fill in missing fields.

now first method tried setting id primary key , insert or replace into. issue previous contents being wiped out.

so im doing update query. im them checking number of rows changed. if below 1 run insert query (if there better way share know has overhead).

anyway issue (finally).. update query records being overwritten null values.

ive condensed snippets of code below:

    $stmt1 = $db->prepare("update results set          field1=?, field2=?, field3=?          id=?     ");      $stmt1->execute(array(         $elm['content1'], $elm['content2'], $elm['content3'], $elm['id']     ));      $count = $stmt1->rowcount();      if ($count < 1) {         $stmt2 = $db->prepare("insert results (id, field1, field2, field3)              values (:id,:field1, :field1, :field1 )         ");          $stmt2->execute(array(":id" => $recordid, ":field1" => $elm['content1'], ":field2" => $elm['content2'], ":field3" => $elm['content3']));         }

the above going on within foreach loop.

is anyway stop content being overwritten if in db. if on update field null add new content, if got in leave unaltered , move on next field. ive read ifnull can used in sqlite im not sure how use within pdo prepared statements.

any help, guidance, examples appreciated :)

p.s im using php5 sqlite

if on update field null add new content, if got in leave unaltered , move on next field.

you can use coalesce this; here example:

~ e$ sqlite3 sqlite version 3.7.5 enter ".help" instructions enter sql statements terminated ";" sqlite> create table foo (a,b,c); sqlite> insert foo values (1,null,3); sqlite> select * foo; 1||3 sqlite> update foo set = + 1, b = coalesce(b,'b'), c = coalesce(c,'c'); sqlite> select * foo; 2|b|3 sqlite>

so, stmt1 be:

$stmt1 = $db->prepare("update results set      field1=coalesce(field1,?), field2=coalesce(field2,?), field3=coalesce(field3,?)     id=? ");

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