MYSQL 5.5删除主键

Question

I am upgrading my quartz.net version from 1.0.3 to 2.0.2 There is a migration script for database schema, which was was written for MSSQL, and I am trying to write a MYSQL version of it.

However, I haven't been able to drop primary keys (which I need to).

Original MSSQL version of script:

ALTER TABLE BLOB_TRIGGERS DROP CONSTRAINT BLOB_TRIGGERS_PKEY;
ALTER TABLE BLOB_TRIGGERS DROP CONSTRAINT BLOB_TRIGGERS_TRIGGER_NAME_FKEY;
ALTER TABLE SIMPLE_TRIGGERS DROP CONSTRAINT PK_SIMPLE_TRIGGERS;
ALTER TABLE SIMPLE_TRIGGERS DROP CONSTRAINT FK_SIMPLE_TRIGGERS_TRIGGERS;
ALTER TABLE CRON_TRIGGERS DROP CONSTRAINT PK_CRON_TRIGGERS;
ALTER TABLE CRON_TRIGGERS DROP CONSTRAINT FK_CRON_TRIGGERS_TRIGGERS;
ALTER TABLE TRIGGERS DROP CONSTRAINT PK_TRIGGERS;
ALTER TABLE TRIGGERS DROP CONSTRAINT FK_TRIGGERS_JOB_DETAILS;
ALTER TABLE JOB_DETAILS DROP CONSTRAINT PK_JOB_DETAILS;

For simplicity, I am trying the first statement there

ALTER TABLE BLOB_TRIGGERS DROP CONSTRAINT BLOB_TRIGGERS_PKEY;

Here are what I have tried and results:

• ALTER TABLE BLOB_TRIGGERS DROP PRIMARY KEY;

[Err] 1025 - Error on rename of '.\\quartz_local#sql-df8_9' to '.\\quartz_local\\BLOB_TRIGGERS' (errno: 150)

• ALTER TABLE BLOB_TRIGGERS DROP INDEX 'PRIMARY';

[Err] 1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''PRIMARY'' at line 1

• ALTER TABLE BLOB_TRIGGERS DROP INDEX PRIMARY ;

[Err] 1025 - Error on rename of '.\\quartz_local#sql-df8_9' to '.\\quartz_local\\BLOB_TRIGGERS' (errno: 150)

• ALTER TABLE BLOB_TRIGGERS DROP PRIMARY KEY;

[Err] 1025 - Error on rename of '.\\quartz_local#sql-df8_9' to '.\\quartz_local\\BLOB_TRIGGERS' (errno: 150)

My Mysql version is 5.5.16

EDIT: To check the indexes:

EDIT2: Foreign keys on request:

Answer 1

(errno: 150) is the giveaway: This means Foreign key definition problem. I suspect some other table has a foreign key constraint depending this PK, so you need to drop that first and rebuild it later.

Edit: With the images you posted, this becomes clearer:

The FK from BLOBS_TRIGGERS to TRIGGERS is made up from the PK. So if you drop the PK, the contraint becomes stale. You need to drop and later recreate the constraint.

Answer 2

After brief Googling, I'm pretty sure the error message is a little misleading. There seem to be a lot of ALTER TABLE statements that might result in that error message.

I'd check to see if there are foreign key references to this table.

Answer 3

I had the same problem. Deleting foreign keys in the table did not help. There were no other tables referencing the one that had the primary key I was trying to drop. I finally solved the problem by using mysqldump to export the table to an ASCII file. I then edited the file to change the primary key to one I wanted, then I reimported using the mysql command line interface.

Answer 4

ALTER TABLE tablename DROP PRIMARY KEY;