Tag Archives: SQL

Oracle: Finding all constraints and their affected columns

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Found an SQL script to list all constraints in an Oracle database together with affected columns. Putting it here in case I need it again… Took a while to run, but sure beats having to look through all the table definitions to find what exactly is preventing me from deleting a row…

SELECT UC.OWNER
,      UC.CONSTRAINT_NAME
,      UCC1.TABLE_NAME||'.'||UCC1.COLUMN_NAME "CONSTRAINT_SOURCE"
,      'REFERENCES'
,      UCC2.TABLE_NAME||'.'||UCC2.COLUMN_NAME "REFERENCES_COLUMN"
FROM USER_CONSTRAINTS uc
,    USER_CONS_COLUMNS ucc1
,    USER_CONS_COLUMNS ucc2
WHERE UC.CONSTRAINT_NAME = UCC1.CONSTRAINT_NAME
  AND UC.R_CONSTRAINT_NAME = UCC2.CONSTRAINT_NAME
  AND UCC1.POSITION = UCC2.POSITION -- Correction for multiple column primary keys.
  AND UC.CONSTRAINT_TYPE = 'R'
ORDER BY UCC1.TABLE_NAME
,        UC.CONSTRAINT_NAME;

If you’re just looking for one particular constraint you can of course also add and UC.CONSTRAINT_NAME = 'SOME NAME' :)

SQL for listing all WordPress tags

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When writing a post I sometimes find it difficult to choose what I should tag it with. I try reuse tags I already have to prevent a total mess, and sometimes I just don’t really remember what tags I have used so far. When writing a post in WordPress you can get a list of the most used ones, but once in a while I write a post on subject I haven’t written a lot about. So, instead of going to the Post Tags page and look through all the pages of tags, I decided to just connect to my blog database and run a query.

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Oracle: How to search for a table or column in a big database

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I needed to find columns containing a certain string. That is, the name of the column should contain that string. Actually not too difficult to do :)

SELECT TABLE_NAME, column_name
FROM all_tab_columns
WHERE column_name LIKE '%FOO_ID%';

That gives you a nice list of all columns containing FOO_ID and what tables you find them in. Fantastic! Now, back to work…

MySQL: How to clone a table

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Ever wanted to, for some reason, clone a database table? Don’t really want to export anything or figure out what statement was used to create that table? Turns out that’s a lot easier to do than I thought it was.

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How to delete WordPress post revisions

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Having revisions on my posts is nice I suppose. But I was starting to get a bit annoyed with the increasingly long list of revisions in each post. And they really did get long. Mainly because I am in a bit of a testing and experimenting phase which means that I have done a lot of adjustments to almost every single post so far because I don’t have 100% control on how I want things or how things will end up looking and so on :P There’s also of course all the obligatory spelling errors I only discover after I have clicked Publish :P

Anyways, I found a nice little MySQL snippet to clear out all of them in a French comment to a blog post. Thought I could share it here. That way I won’t lose it either :)

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