MySQL supports a multi-table UPDATE syntax, which would look approximately like this: You can update the Train table and delete from the Reservations table in the same transaction. As long as you do the update first and then do the delete second, it should work.
I am working with a query which contains “CASE” statement within “WHERE” clause. But SQL Server 2008 is giving some errors while executing it. Can anyone please help me with the correct query? Here is the query:
If that’s a SQLException thrown by Java, it’s most likely because you are trying to get or set a value from a ResultSet, but the index you are using isn’t within the range. For example, you might be trying to get the column at index 3 from the result set, but you only have two … Read more
You are mixing implicit joins with explicit joins. That is allowed, but you need to be aware of how to do that properly. The thing is, explicit joins (the ones that are implemented using the JOIN keyword) take precedence over implicit ones (the ‘comma’ joins, where the join condition is specified in the WHERE clause). Here’s an outline of … Read more
New versions of MySQL WorkBench have an option to change specific timeouts. For me it was under Edit → Preferences → SQL Editor → DBMS connection read time out (in seconds): 600 Changed the value to 6000. Also unchecked limit rows as putting a limit in every time I want to search the whole data … Read more
You can simply add another join like this: However be aware that, because it is an INNER JOIN, if you have a message without an image, the entire row will be skipped. If this is a possibility, you may want to do a LEFT OUTER JOIN which will return all your dashboard messages and an image_filename only if … Read more
UNION puts lines from queries after each other, while JOIN makes a cartesian product and subsets it — completely different operations. Trivial example of UNION: similary trivial example of JOIN:
I’m trying to use MySQL to create a view with the “WITH” clause But it doesn’t seem like MySQL supports this. I thought this was pretty standard and I’m sure Oracle supports this. Is there anyway to force MySQL to use the “WITH” clause? I’ve tried it with the MyISAM and innoDB engine. Both of … Read more
An ORA-01722 error occurs when an attempt is made to convert a character string into a number, and the string cannot be converted into a number. Without seeing your table definition, it looks like you’re trying to convert the numeric sequence at the end of your values list to a number, and the spaces that … Read more
Yes, it a vice versa. It depends on which side of the relationship the entity is present on. For example, if one department can employ for several employees then, department to employee is a one to many relationship (1 department employs many employees), while employee to department relationship is many to one (many employees work … Read more