Questions[sql](ubuntu)

This website explains MySQL server installation in Ubuntu 18.04. Basically you issue the command sudo apt install mysql-server. The same website then explains that:

Once the installation is completed, the MySQL service will start automatically. To check whether the MySQL server is running, type: sudo systemctl status mysql

Does this imply that once I install mysql-server it will always be running in the background unless I explicitly kill the process upon each reboot?

I want to play around with mysql-server occasionally, but don't want it constantly running in the background.

I installed the sqlserver based on the Microsoft Documentation. The following commands are executed correctly.

wget -qO- https://packages.microsoft.com/keys/microsoft.asc | sudo apt-key add -

sudo add-apt-repository "$(wget -qO- https://packages.microsoft.com/config/ubuntu/16.04/mssql-server-2017.list)"

sudo apt-get update
sudo apt-get install -y mssql-server

sudo /opt/mssql/bin/mssql-conf setup

systemctl status mssql-server

But when I try to install the SQL Server command-line tools,the following error occurs.

sudo apt-get install mssql-tools unixodbc-dev


Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 mssql-tools : Depends: msodbcsql17 (>= 17.3.0.0) but it is not going 
 to be installed
           Depends: msodbcsql17 (< 17.4.0.0) but it is not going to be 
  installed
 E: Unable to correct problems, you have held broken packages.

My operation system is Linux Ubuntu 18.04.1 LTS

How to install sql developer on lubuntu 18.04

I tried the below link from Oracle (served as installation notes when you download sql developer) but that dint work.

https://www.oracle.com/technetwork/developer-tools/sql-developer/downloads/sqldev-install-linux-1969676.html

Error:

Error:

Oracle now provides .rpm files instead of .zip and all the answers on this site help you with the .zip but not .rpm

I'm a longtime GUI user trying to switch to command line, and I'm not sure how to execute an SQL statement from the Ubuntu command line. I'm using postgres. I can use \c to connect to the database and \d to see the tables in it. I can also see the headers with \d dbname (where dbname is the name of the database). What I can't do is see the actual data.

I tried SELECT * FROM dbname; and I got a "syntax error at or near dbname". I Tried it without the semi colon, and just got a new command line. How do I see my data? Thanks in advance.

I am not able to run sqlcmd command
My OS (18.04) is

$ uname -a Linux Linux 4.15.0-23-generic #25-Ubuntu SMP Wed May 23 18:02:16 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

$ sqlcmd -S localhost -U SA -P 'password'
Sqlcmd: Error: Microsoft ODBC Driver 17 for SQL Server : Login timeout expired.
Sqlcmd: Error: Microsoft ODBC Driver 17 for SQL Server : TCP Provider: Error code 0x2749.
Sqlcmd: Error: Microsoft ODBC Driver 17 for SQL Server : A network-related or instance-specific error has occurred while establishing a connection to SQL Server. Server is not found or not accessible. Check if instance name is correct and if SQL Server is configured to allow remote connections. For more information see SQL Server Books Online..