I know that this question has been already answered a million of times, but I couldn’t find any solution. Well I have these three tables on postgres sql. When I try to create the table incident_has_volunteer it throws the error there is no unique constraint matching given keys for referenced table “incident”. I tried to add on the third table
SQL using If Not Null on a Concatenation
If I have the table SELECT (Firstname || ‘-‘ || Middlename || ‘-‘ || Surname) AS example_column FROM example_table This will display Firstname-Middlename-Surname e.g. John–Smith Jane-Anne-Smith …
Spark SQL passing a variable
I have following Spark sql and I want to pass variable to it. How to do that? I tried following way. Answer You are almost there just missed s 🙂
Select certain column only if condition met
I want to have a select that will not have fixed number of columns. Column OptionalColumn should be selected only if variable @check = 1 This is what I had (syntax is bad but maybe it explains my problem) It is crucial to have it only if @Check = 1 and not having it if @Check = 0. Is it
MySQL: How to convert seconds to mm:ss format?
I want to convert seconds to minute : seconds format in sql select statement. At the moment I am using: It works perfectly but it gives me this format of time: hh:mm:ss but I need mm:ss Is it possible to convert seconds into mm:ss format using sql query? Answer If the value is less than an hour, then just do:
How to implement and insert value SQL specialization/generalization
I have my table with these 3 entities: student, lecturer and person. Person will be the parent that holds common attributes of student and lecturer. This is my database design, is this a correct way …
SQL Updating column after adding it giving “Invalid column name” error
I have the following SQL in SQL Server 2005 but I get an error stating “Invalid column name ‘ExpIsLocalTime’ (ln 7) when I run it: IF NOT EXISTS(SELECT * FROM sys.columns WHERE Name = N’…
Update and insert to one table from another
I have two tables: table1: (ID, Code, Name) table2: (ID, Code, Name) with same columns I want to to insert data from table1 to table2 or update columns if that exists in table2 (table1.ID = table2.ID) What is the simple way to do this? WITH OUT MERGE Answer There are some issues with Merge statement,so it should be used with
How to decide which fields must be indexed in a database table
Explanation I have a table which does not have a primary key (or not even a composite key). The table is for storing the time slots (opening hours and food delivery available hours) of the food shops. Let’s call the table “business_hours” and the main fields are as below. shop_id day (0 – 6, means Sunday – Saturday) type (open,
Checking if a value exists in sqlite db with Go
I’m writing code to manage users in a sqlite database with Go. I’m trying to check if a username is taken, but my code is ugly. My table looks like: And I check if a username is taken with: Is there a better query I could use that would tell me if the username value exists in the table in