Question

I am running following query throgh phpMyAdmin:

**CREATE TABLE folders (
  folder_id SERIAL NOT NULL,
  parent_id BIGINT,
  folder_name TEXT NOT NULL,
  PRIMARY KEY (folder_id),
FOREIGN KEY (parent_id) REFERENCES folders(folder_id) ON DELETE CASCADE
)ENGINE=InnoDB;**

but it is giving the following error:
#1005 – Can’t create table ‘filesharingnew.folders’ (errno: 150)
Any idea where I am wrong?

Answer 1

From MySQL docs, Numeric Type Overview:

SERIAL is an alias for BIGINT UNSIGNED NOT NULL AUTO_INCREMENT UNIQUE.

You should change parent_id into BIGINT UNSIGNED so it matches the referenced column.