SSH into the machine. Using the proper credentials and ip address, ssh [email protected]. This should provide you with shell access to the Ubuntu server. Restart the mySQL service. sudo service mysql restart should do the job. If your mySQL service is named something else like mysqld you may have to change the command accordingly or try this: sudo /etc/init.d/mysql restart
Short answer: Yes, it can be NULL or duplicate. I want to explain why a foreign key might need to be null or might need to be unique or not unique. First remember a Foreign key simply requires that the value in that field must exist first in a different table (the parent table). That … Read more
They don’t have the same structure… I can guarantee they are different I know you’ve already created it… There is already an object named ‘tbltable1’ in the database What you may want is this (which also fixes your other issue):
Yes, this is a common aggregation problem. Before SQL3 (1999), the selected fields must appear in the GROUP BY clause[*]. To workaround this issue, you must calculate the aggregate in a sub-query and then join it with itself to get the additional columns you’d need to show: But you may also use window functions, which looks simpler: The … Read more
You need to use HAVING, not WHERE. The difference is: the WHERE clause filters which rows MySQL selects. Then MySQL groups the rows together and aggregates the numbers for your COUNT function. HAVING is like WHERE, only it happens after the COUNT value has been computed, so it’ll work as you expect. Rewrite your subquery as:
The error message will include the name of the constraint that was violated (there may be more than one unique constraint on a table). You can use that constraint name to identify the column(s) that the unique constraint is declared on Once you know what column(s) are affected, you can compare the data you’re trying … Read more
They are speaking the same thing and it has to do with tuples (relational algebra) or rows (layman’s term). When it says high-cardinality are possible values of particular attribute (or field) that are unique and therefore the number of rows or tuples are higher: Example: As far as as StudentID the cardinality is high because it is unique. In this it … Read more
You’ll need to put your current query in subquery as below : Oracle applies rownum to the result after it has been returned.You need to filter the result after it has been returned, so a subquery is required. You can also use RANK() function to get Top-N results. For performance try using NOT EXISTS in place of NOT IN. See this for more.
When creating the TABLE under B2BOWNER, be sure to prefix the PL/SQL function with the Schema name; i.e. B2BOWNER.F_SSC_Page_Map_Insert. I did not realize this until the DBAs pointed it out. I could have created the table under my root USER/SCHEMA and the PL/SQL function would have worked fine.