How do I fix mysql error 150?

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How do I fix mysql error 150?

Altering a table returns an error (errno: 150) if a foreign key definition is incorrectly formed for the altered table. Dropping an index required by a foreign key constraint. The foreign key constraint must be removed before dropping the index.

How do I reference a foreign key in mysql?

Following are the syntax of the ALTER TABLE statement to add a foreign key in the existing table:

  1. ALTER TABLE table_name.
  2. ADD [CONSTRAINT [symbol]] FOREIGN KEY.
  3. [index_name] (column_name.)
  4. REFERENCES table_name (column_name,…)
  5. ON DELETE referenceOption.
  6. ON UPDATE referenceOption.

What is a foreign key constraint fails?

The error message itself showing there is a foreign key constraint error, which means you are deleting a parent table where the child table contains the Primary table identifier as a foreign key. To avoid this error, you need to delete child table records first and after that the parent table record.

How do I create a new table in Navicat?

To begin, in Navicat, right click on the Tables item within the listing for your database, in the table of contents area, and choose New Table from the menu. This will open the table creation dialogue. You can also click on the New Table icon.

How do I delete a foreign key constraint in SQL?

To delete a foreign key constraint

  1. In Object Explorer, expand the table with the constraint and then expand Keys.
  2. Right-click the constraint and then click Delete.
  3. In the Delete Object dialog box, click OK.

How do I reference in MySQL?

The references keyword is used to define which table and column is used in a foreign key relationship. This means that a record in the hobby table must have a person_id that exists in the person table or else at the time of insert you will receive an error that the key does not exist.

How can I get data from another table using foreign key?

  1. The INSERT statement conflicted with the FOREIGN KEY.
  2. Table contains no primary or candidate keys that match the referencing column list in the foreign key.
  3. primary and foreign key problem.
  4. Insert automatic generate id as foreign key to another table.
  5. Sql – same data column retrieval.

Do foreign keys improve performance?

It’s a common mistake to avoid creating foreign keys in a database because they negatively impact the performance. It is true that foreign keys will impact INSERT, UPDATE and DELETE statements because they are data checking, but they improve the overall performance of a database.

How do you break a foreign key constraint?

You can try it if the commands do not work.

  1. Expand your database view.
  2. Right Click on Table which has foreign key constraint.
  3. Right click on the column which has the foreign key reference.
  4. A list of relationships will appear (if you have one) in a pop up window.
  5. From there you can delete the foreign key constraint.

How do I use Navicat?

Steps to connect to your database with Navicat

  1. Open Navicat.
  2. Click the Connection button at the top right of Navicat.
  3. Enter your Database Connection credentials.
  4. You should get a Connection Successfulpop up.
  5. Click Ok again to accept the Connection Settings.

How do I create a navicat connection?

To create a new connection, click or choose File -> New Connection. Then, enter the necessary information in Connection Properties window….The remote MySQL server connection settings are:

  1. Host Name/IP Address: server1.navicat.com.
  2. Port: 4406.
  3. User Name: navicat.
  4. Password: testnavicat.