I'm not a DB person but something weird is happening in Access:
I'm trying to run this SQL command: UPDATE tbl_DirectorySet SET TempRootDir='D';
on this table:
It doesn't do anything! I mean the field is empty as before.
If I manually set the field with some value like "aaaaa", then after I run the SQL command I can see that the command worked as expected.
If you don't have any record in a cell, the UPDATE command won't work. Use INSERT instead. That's why it works when you first introduce "aaaaa" and then you UPDATE.
EDIT: this link may make you understand better the principles behind the basic SQL commands: https://en.wikipedia.org/wiki/Create,_read,_update_and_delete
Related
I am currently taking CS50, an online introductory course in coding by Harvard. We have just covered SQL and I am trying to attempt the question "Movies" in the problem set now, a description of which can be found here: https://cs50.harvard.edu/x/2020/psets/7/movies/
However, I am not sure how to do this correctly.
For example, for 1.sql, my code is as follows:
SELECT title FROM movies WHERE year = 2008;
I literally wrote only that one line and nothing more in the file "1.sql".
But when I run
$ cat 1.sql | sqlite3 movies.db
in my terminal, nothing happens?
Is this how I am supposed to write code for SQL? Or am I missing some stuff that I should be including (e.g. as headers or what) above my query?
To be clear, I believe I know how to write a query itself but I do not know the "protocol" to write it, if I may. I mean, for example, I am positively sure that "SELECT title FROM movies WHERE year = 2008;" fulfils the question's first requirement.
Some enlightenment would be appreciated!
EDIT 1
Okay first I must apologise to everyone who so very kindly took the time to comment on my post. For some very odd reason, my query did not return any results the first time I ran it. However, when I tried it again, it worked perfectly! Not sure what went wrong honestly, but all is well now! So sorry for wasting everyone's time ):
EDIT 2
Okay I also figured out that the reason why I could not execute my query is that I was in "sqlite3" in my terminal. I was supposed to run the command to execute my query in the main terminal i.e. not when it says "sqlite3". Stupid. I know.
Option 1) you can run "$ cat 1.sql | sqlite3 movies.db" in your normal terminal (not in the sqlite3 mode)
Option 2) you can open sql environment by typing "sqlite3 movies.db" (it will open movies.db if it exists, or create a temporary one if it doesn't exist). Then you can type ".read 1.sql" after the "sqlite>"
Open Browser and test it as mention on your course site
Usage
To test your queries on CS50 IDE, you can query the database by running
$ cat filename.sql | sqlite3 movies.db
where filename.sql is the file containing your SQL query.
Or you can paste them into DB Browser for SQLite’s Execute SQL tab and click ▶.
I am using Oracle SQL Developer 4.0.3.16, and since a few weeks, the shortcut Ctrl+Enter doesn't execute the current line or statement anymore, except for when I highlight it, but instead does run my whole worksheet. Using the green button on the top, which is supposed to only run the current line results in the same behaviour (except for when the line is highlighted). Hovering over the button still reveals the tooltip "Run Statement (Ctrl+Enter)". A colleague of mine does get this problem too.
I also looked into the Preferences->Shortcut Keys menu, but the shortcut set for running a statement is still Ctrl+Enter.
Anyone knows what's wrong with my SQL Developer?
Every SQL statement in SQL Developer should have semicolon ; otherwise ctrl+Enter would execute will execute entire worksheet.
Suppose for example I have two SQL statements:
1.select * from emp without semicolon ;
2.UPDATE EMP SET DEPT_ID=10; WITH SEMICOLON ;
Then it will execute both statement simultaneously for that you should have semicolon after each SQL statement.
I faced it too. Usually you'll have PL/SQL block above the SQL code you are trying to execute. Comment out the PL/SQL block which is DECLARE, BEGIN without ending in semicolon creating this issue. So commenting the PL/SQL block in worksheet should solve your issue.
Thanks to the answer here: if it doesn't work even with a semicolon after the line like it didn't for me (Oracle SQL Developer 3.2.20.10), you need to put a '/' after each command if you want to execute them all independently, e.g.:
blahblah;
/
blahblah;
/
Think of the '/' as the real terminator/separator here.
I think I kinda solved it.
Since I'm not an administrator on the computers at work I couldn't install a new client, so I downloaded the SQL Developer in version 4.0.3.16 a while ago and just ran it locally from my user directory.
Meanwhile the client 4.0.3.16 is installed on the OS and when using this client I don't get this bug.
Thanks for the help though.
Using Navicat, I am running an SQL Merge Command, Navicat seems to drop off the ; from the end of the command, causing it to fail.
I can't find a way to change the terminator character to something like #.
well, I kinda gave up on it. :-) I just put it in a Stored Procedure - works fine, but I was hoping to find a "query" fix.
I have used mysql for some projects and recently I moved to postgresql. In mysql when I alter a table or a field the corresponding query will be displayed in the page. But such a feature was not found in postgresql(kindly excuse me if I'm wrong). Since the query was readily available it was very helpful for me to test something in the local database(without explicitly typing the query), copy the printed query and run it in the server. Now it seems like I've to manually do all the trick. Even though I'm familiar with the query operations,at times it can be pretty time consuming process. Can anybody help me? How can I get the corresponding query to get displayed in postgresql(like in mysql) whenever a change is made to the table?
If you use SELECT * FROM ... there should not be any reason for your output to not include newly added columns, no matter how you get your results - would that be psql in command line, PgAdmin3 or any other IDE.
After you add new columns, it is possible that these changes are still in open transaction in other window or SQL command - be sure to COMMIT such transaction. Note that your changes to data or schema will not be visible to any other database clients until transaction commits.
If your IDE still does not show changes, maybe you need to refresh list of tables or if that option is not available, restart your IDE. If that does not work still, maybe you should use better IDE.
If you have used SELECT field1, field2, ... FROM ... then you must add new fields into your SELECT statement(s) - but this would be true for any other SQL implementation, MySQL included.
You could use the LISTEN / NOTIFY mechanism in PostgreSQL to notify your client on altering the database schema.
I'm working in Ubuntu with MySql and I also have Query Browser and Administrator installed, I'm not afraid of the command line either if it helps.
I want simply to be able to run a query and see a result set but then convert that result set into a series of commands that could be used to create the same rows in a table of an identical schema.
I hope the question makes sense, it's quite a simple problem and one that must have been solved but I can't for the life of me work out where this kind of conversion is made available.
Thanks in advance,
Gav
I think you need to use a command line utility mysqldump http://dev.mysql.com/doc/refman/5.1/en/mysqldump.html
if you want to dump one or more tables.
If you need to dump a result of an arbitrary query and restore it later, take a look on SELECT ... INTO OUTFILE and LOAD DATA INFILE( http://dev.mysql.com/doc/refman/5.0/en/load-data.html)
I do not know if I understood you at all but you can use a SELECT INTO statement.
SELECT *
INTO new_table_name
FROM old_tablename
WHERE ...