I’m trying to add barista_grade_id to the baristas table as a foreign key and I’ve looked every where on what syntax to use and it seems to be unanimous that this is the correct way. I did it before this and it worked. but because of some mistakes I deleted it and redo it again, but for whatever r…
Tag: alter-table
Modify generated column in Oracle
I have created a database table in Oracle with an auto generated column: Now I do not need it to be generated automatically. I tried to write: But it did not work. The database gives an error: Can someone please explain how to solve this issue without dropping the column? Answer (There’s no such thing a…
Why can’t I add a column to an existing table with a checkConstraint that references other columns in SQL
I’m using SQL Server and am trying to add a column and a check constraint. I’ve found that the following works: However a less verbose way of writing this does not work: The following error is output: Column CHECK constraint for column ‘isTrue’ references another column, table ‘t…
How do I make sure that all rows with the same foreign key have unique names in my PostgreSQL database?
I have a PostgreSQL database with two tables: Team and Project, in a one-to-many relationship. Team has these columns: id name Project has these: id name team_id I’d like to make sure that the projects within a team must have unique names. Projects belonging to different teams should be able to share na…
add not null column take values from other column
I have an existing table say, Items with Id | CreateDate (as DateTime) columns; want to add Year int not null, take the default year from the CreateDate column. The Year value will be futer updated …
How to I create a new column in a table and add values to it
I have to create a new column in my table called Raise that has a 20% raise from the values of the SAL column, here’s what I have so far: SELECT ENAME,EMPNO, JOB, SAL from emp ALTER TABLE emp ADD …
Oracle: How to change column data type from VARCHAR to NUMBER without losing data
I have the following columns in my table: ID – NUMBER(10,0) NUMBER – VARCHAR(255) All data in the NUMBER column are numbers. I would like to change the VARCHAR type to Integer Number type. How to do it without data loss? Answer Oracle does not allow modification of data type of the column if it is…
How to avoid adding duplicate foreign key constraints
I would to know if it is possible to avoid adding several times the same foreign key constraint? Example: if I execute 3 times the query below, the constraint will exist with 3 times in phpmyadmin… It would be great that it would be rejected the second and third time I apply that query. Answer You can g…
How can I update the table in SQL?
I’ve created a table called Youtuber, the code is below: In this table, there are 2 channels: So, I want to edit the age of “Grandtour Games” to “18”. How can I do that with update? Is my code right? Answer No, in update, you’ll have to follow this sequence: In your code, p…
SQL Server 2012 takes long time on simple alter to add NULL columns
I have a problem to alter table in SQL Server 2012, it takes a long time to add 04 columns being allowed NULL to large table with 340 columns and approximately 166M rows and 01 non-clustered index This problem happens only specific table after restoring. I’m waiting the execution for 10 hours but itR…