Add new column to wordpress database - php

Question

I trying update my plugin. So I must upgrade mysql_table. But when trying new column, program get exception.
This is my current table :
$sql = "CREATE TABLE {$table_name} (
say_id int(11) not null AUTO_INCREMENT,
customer_mail text not null,
customer_name text not null,
customer_messagge text not null,
messagge_date_time datetime not null,
PRIMARY KEY (say_id)
)ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1";
require_once(ABSPATH . "wp-admin/includes/upgrade.php");
dbDelta($sql);
Now I am add colum more one table. I try Alter table, this working one time and add a column but one more refresh I get this error.
This is mycode
$wpdb->query("ALTER TABLE wp_customer_say ADD say_state INT(1) NOT NULL DEFAULT 1");
And this is my error
WordPress database error: [Duplicate column name 'say_state']
ALTER TABLE wp_customer_say ADD say_state INT(1) NOT NULL DEFAULT 1
I see this error and ı try this;
$query = $wpdb->query("select * from wp_customer_say");
$respond = mysql_num_fields( $query );
$column_array = array();
for($i = 0; $i < $respond ; $i++):
$column_array[] = mysql_field_name($query,$i);
endfor;
if( !in_array("say_state",$column_array) ):
$wpdb->query("ALTER TABLE wp_customer_say ADD say_state INT(1) NOT NULL DEFAULT 1");
endif;
and I get this error.
Warning: mysql_num_fields() expects parameter 1 to be resource, integer given in
Help please. Thank you.
Sorry bad english.

Answer 1

Use this query. I use only mysql-standred for get field name by fast query and this will solve your problem:
$row = $wpdb->get_results( "SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = 'wp_customer_say' AND column_name = 'say_state'" );
if(empty($row)){
$wpdb->query("ALTER TABLE wp_customer_say ADD say_state INT(1) NOT NULL DEFAULT 1");
}

Answer 2

You can check column name exists in WordPress using below way,
$myCustomer = $wpdb->get_row("SELECT * FROM wp_customer_say");
//Add column if not present.
if(!isset($myCustomer->say_state)){
$wpdb->query("ALTER TABLE wp_customer_say ADD say_state INT(1) NOT NULL DEFAULT 1");
}

Answer 3

Best and correct way to add new column into the table if column not exists.
/*# Add status column if not exist */
global $wpdb;
$dbname = $wpdb->dbname;
$marks_table_name = $wpdb->prefix . "wpsp_mark";
$is_status_col = $wpdb->get_results( "SELECT `COLUMN_NAME` FROM `INFORMATION_SCHEMA`.`COLUMNS` WHERE `table_name` = '{$marks_table_name}' AND `TABLE_SCHEMA` = '{$dbname}' AND `COLUMN_NAME` = 'status'" );
if( empty($is_status_col) ):
$add_status_column = "ALTER TABLE `{$marks_table_name}` ADD `status` VARCHAR(50) NULL DEFAULT NULL AFTER `attendance`; ";
$wpdb->query( $add_status_column );
endif;

Answer 4

Just wanted to add that there's a slightly better way to do this than #Amandeep Wadhawan's answer.
register_activation_hook(__FILE__, 'install_tables');
function install_tables()
{
update_options('my_plugins_current_db_version', 0); // Replace 0 with whatever your final database version is
// Code here to create the final version of your database tables
}
add_action('plugins_loaded', 'update_databases');
public function update_databases()
{
global $wpdb;
$prefix = $wpdb->prefix;
$a_table_to_update = $prefix . $a_table_to_update;
$current_version = get_option('my_plugins_current_db_version', 0);
switch($current_version)
{
// First update
case 0:
// first update code goes here (alter, new table, whatever)
$current_version++;
case 1:
// next update code goes here
$current_version++;
}
update_option('my_plugins_current_db_version', $current_version);
}
You just have to make sure that your install_tables() function will always create the tables that reflect the final version number and sets the my_plugins_current_db_version option to the final version number.
Then in the update_databases() function you just have to make sure to increment $current_version before each subsequent case.
With this set-up you can blindly update without having to unnecessarily query to find out if columns or tables exist first - and less queries are always a good thing....especially if your update code is firing on the plugins_loaded hook.
It is also much cleaner, shows a clear upgrade path, and only executes necessary updates - so it is more efficient.

Answer 5

I really like Rikesh's option (even upvoted!), but I think to prevent hardcoding information which could change, such as $table_prefix from the wp-config.php file, this option is a safer bet.
// Replace `table_name` with the actual table name
$table = $table_prefix.'table_name';
// And use sprintf to pass the table name
// Alternatively, you can use $table instead of sprintf,
// if you use double quotes such as shown here
$myCustomer = $wpdb->get_row( sprintf("SELECT * FROM %s LIMIT 1", $table) );
// If you prefer not using sprintf, make sure you use double quotes
// $myCustomer = $wpdb->get_row( "SELECT * FROM $table LIMIT 1" );
// Replace "missing_field" by the column you wish to add
if(!isset($myCustomer->missing_field)) {
$wpdb->query( sprintf( "ALTER TABLE %s ADD phone2 VARCHAR(255) NOT NULL", $table) );
// Alternate example using variable
// $wpdb->query( "ALTER TABLE $table ADD phone2 VARCHAR(255) NOT NULL") );
}

Answer 6

Wrote a good solution, it works in all cases
$check_column = (array) $wpdb->get_results( "SELECT count(COLUMN_NAME) FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME = '{$wpdb->prefix}my_table' AND COLUMN_NAME = 'some_name'" )[0];
$table_name = $wpdb->prefix . 'my_table';
$check_column = (int) array_shift($check_column);
if($check_column == 0) {
$wpdb->query(
"ALTER TABLE $table_name
ADD COLUMN `some_name` VARCHAR(55) NOT NULL
");
}

Answer 7

$myCustomer = $wpdb->get_row("SELECT * FROM wp_customer_say");
//Add column if not present.
if(!isset($myCustomer->say_state)){
$wpdb->query("ALTER TABLE wp_customer_say ADD say_state INT(1) NOT NULL DEFAULT '' ");
This code it will fail if you have no records in the database. Only works if you have at least one record saved in your database.