CODEWITHSUNDEEP
phpmysql
Christoph C.
Christoph C.

Reputation: 938

PHP/MySQL: Move data from old database (tables without an ID) to new database (tables with an ID)

I have a function which gets me all tables with their columns from an old database to a new database. Everything is working fine so far. Now I need to extend that function, so that in all tables inside my new database a surrogate key (primary key ID with auto increment) will be added.

Old DB:

+-----------------------------------+------------+--------+
|               Col1                |    Col2    | NumCol |
+-----------------------------------+------------+--------+
| Value 1                           | Value 2    |    123 |
| This is a row with only one cell  |            |        |
| This row is testing html entities | Te<br />st |     45 |
+-----------------------------------+------------+--------+

New DB:

+----+-----------------------------------+------------+--------+
| ID |               Col1                |    Col2    | NumCol |
+----+-----------------------------------+------------+--------+
|  1 | Value 1                           | Value 2    |    123 |
|  2 | This is a row with only one cell  |            |        |
|  3 | This row is testing html entities | Te<br />st |     45 |
+----+-----------------------------------+------------+--------+

So as you can see, everything remains the same except the new column ID in every table.

Here is my function to copy everything from my old DB to my new DB: 

public function loadOldDBtoNewDB($oldDB,$newDB){
    $sqlshowTables = "SHOW TABLES ";
    $statement = $this->db->prepare($sqlshowTables);
    $statement->execute();
    $tables = $statement->fetchAll(PDO::FETCH_NUM);

    foreach($tables as $table){
        $sql[] = "INSERT INTO ".$newDB.".`".$table[0]."` SELECT * FROM ".$oldDB.".`".$table[0]."`; ";
    }

    $sqlState = implode(' ', $sql);
    $executeStatement = $this->db->exec($sqlState);

}

Note: Old DB and new DB already exist when I run this function.

So how do I need to change my inser statement so that an ID (auto increment) column will be added during every insert?

Upvotes: 1

Views: 89

Answers (2)

Raja vikraman
Raja vikraman

Reputation: 169

u can also create new table with following command

create table new_table as (select * from old_table);

alter table new_table add column id primary key auto_increment;

Upvotes: 1

Qirel
Qirel

Reputation: 26460

Your new table should already have an AUTO_INCREMENT on the id column. Then supply a NULL value to it when doing the select!

If your new table doesn't have auto-increment set on the ID column, add it by

ALTER TABLE `mytablename` 
CHANGE `ID` `ID` INT(11) NOT NULL AUTO_INCREMENT

Add a NULL before the * in your SELECT - this will force the ID (which appears first in your column-list) to use the AUTO_INCREMENT, since it cannot be NULL.

$sql[] = "INSERT INTO ".$newDB.".`".$table[0]."` SELECT NULL, * FROM ".$oldDB.".`".$table[0]."`; ";

Upvotes: 1

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