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MYSQL Update all foreign key values

I have two identical tables that are located in two identical databases(with different name). I want to merge these two tables, but their primary keys are used in other tables, these tables look …

Filtering with Joins – Rails

I have two models Product and ProductProperties. So, I store the properties for products in the Product Properties model which is associated with another model Properties How can I implement a scope …

JOIN (SELECT … ) ue ON 1=1?

I am reading an SQL query in Redshift and can’t understand the last part: … LEFT JOIN (SELECT MIN(modified) AS first_modified FROM user) ue ON 1=1 What does ON 1=1 mean here?

Using EXCEPT clause in PostgreSQL

I am trying to use the EXCEPT clause to retrieve data from table. I want to get all the rows from table1 except the one’s that exist in table2. As far I understand, the following would not work: The only way I can use EXCEPT seems to be to select from the same tables or select columns that have the