SELECT DISTINCT on one column
Assuming that you’re on SQL Server 2005 or greater, you can use a CTE with ROW_NUMBER():
sql
postgresql: error duplicate key value violates unique constraint
As the error message tells you – you can not have two rows with the same value in the columns dementia_type, snapid since they need to be unique. You have to make sure that the two databases has the same values for dementia_type, snapid. A workaround would be to add a column to your table alter table t_types_of_dementia add … Read more
Generating a random & unique 8 character string using MySQL
This problem consists of two very different sub-problems: the string must be seemingly random the string must be unique While randomness is quite easily achieved, the uniqueness without a retry loop is not. This brings us to concentrate on the uniqueness first. Non-random uniqueness can trivially be achieved with AUTO_INCREMENT. So using a uniqueness-preserving, pseudo-random … Read more
Conversion failed when converting the varchar value ‘simple, ‘ to data type int
In order to avoid such error you could use CASE + ISNUMERIC to handle scenarios when you cannot convert to int.Change To Basically this is saying if you cannot convert me to int assign value of 0 (in my example) Alternatively you can look at this article about creating a custom function that will check … Read more
Fatal error: Please read “Security” section of the manual to find out how to run mysqld as root
I’m using OS X (Yosemite) and this error happened to me when I upgraded from Mavericks to Yosemite. It was solved by using this command
What is the purpose of using WHERE 1=1 in SQL statements?
Yeah, it’s typically because it starts out as ‘where 1 = 0’, to force the statement to fail. It’s a more naive way of wrapping it up in a transaction and not committing it at the end, to test your query. (This is the preferred method).
DB2 SQL error sqlcode=-104 sqlstate=42601
You miss the from clause
Using group by on multiple columns
Group By X means put all those with the same value for X in the one group. Group By X, Y means put all those with the same values for both X and Y in the one group. To illustrate using an example, let’s say we have the following table, to do with who is attending what subject at … Read more
Difference between View and table in sql
A table contains data, a view is just a SELECT statement which has been saved in the database (more or less, depending on your database). The advantage of a view is that it can join data from several tables thus creating a new view of it. Say you have a database with salaries and you need to … Read more
SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax — PHP — PDO [duplicate]
from is a keyword in SQL. You may not used it as a column name without quoting it. In MySQL, things like column names are quoted using backticks, i.e. `from`. Personally, I wouldn’t bother; I’d just rename the column. PS. as pointed out in the comments, to is another SQL keyword so it needs to … Read more