I have a table set which contains two columns: setId and value.
setId is referenced to a baseEnum setBE, containing the values A, B, C and D.
Data in this table:
A, 10
B, 20
D, 25
Another table setExt contains two columns: setId and extension.
setId should be referenced to the baseEnum setBE, but only values existing in first table set should be able to choose, in this case:
A
B
D
Problem is ( imho ) the fact that the first table refers to a baseEnum and not to an EDT, correct? Any possibilities to achieve this?
Related
How i can to make a dynamic, calculated column? Which is calculated using other columns and not stored in the database.
Which can be used for data output and sorting.
Library: stephencelis/SQLite.swift (https://github.com/stephencelis/SQLite.swift)
Example:
SELECT a+b as c from test ORDER BY c ASC;
Thanks.
With sqlite 3.31.0 and newer, you can use a generated column.
CREATE TABLE test(a INTEGER, b INTEGER,
c INTEGER GENERATED ALWAYS AS (a + b) VIRTUAL);
Or use a view:
CREATE TABLE real_test(a INTEGER, b INTEGER);
CREATE VIEW test AS
SELECT a, b, a + b AS c FROM real_test;
TABLE one:
A B C
TABLE two:
A B D C
As you can see column D was added to the middle.
How to copy record from table one to table two setting value D to default.
Don't use D in the list of columns of Table2:
INSERT INTO Table2(A, B, C)
SELECT A, B, C FROM Table1
Maybe you need a WHERE clause also if you want to copy a specific row only.
D will get its default value, if there is one defined in the CREATE statement of Table2, or null if there isn't a default value.
I have 2 tables, which has one - many relation ship. The child table has 4 columns (Let say, A, B, C, D)
A - Table column
B - Foreign key column
C - Foreign key column
D - Table column
Requirement is to sort the data by A, B,then by C when displaying records
I tried with query script but not working. (Relation data source doesn't load)
I tried with specifying the sort field on Relations tab (Sorting work only for table column, fk columns are not displayed)
Is there a way to do this?
I have a table where data is as given below
My requirement is to update this table in such a way that, within a group (grouping will be done based on column A), if there is value in column B, same value should be updated to other rows in column B having null values within that group. If column B have null value for all the records within that group, then new sequence should be generated.Also I can't use pl/SQL block for this. I need to write a SQL query to perform this
My expected output is given below
You won't be able to use the sequence_name.nextval directly in your update statement, as the value will increase with every row, meaning that you would end up with different values in your b column for each a value.
The best way round that I can think of doing this is to first of all ensure every set of all-null b values has a single value in it, which you can do as follows:
merge into t1 tgt
using (select a,
b,
rid,
row_number() over (partition by a order by b) rn
from (select a,
b,
rowid rid,
max(b) over (partition by a) max_b
from t1)
where max_b is null) src
on (tgt.rowid = src.rid and src.rn = 1)
when matched then
update set tgt.b = t1_seq.nextval;
This finds the rows which have all the b values as null for a given a, and then updates one of them to have the next sequence value.
Once you've done that, you can then go ahead and populate the null values based on the max b value for that group, like so:
update t1
set b = (select max(b) from t1 t2 where t1.a = t2.a)
where b is null;
See this LiveSQL script for evidence that this works.
Something like this:
update table t1
set B = (select nvl(max(b),sequence_name.nextval) from table where a=t1.a)
Ps: I couldn't test this.
Indeed we can't use sequences in correlated subqueries... :(
One workaround is the use of merge :
merge into teste t1
using (select max(b) as m,a from teste group by a) t2
on (t1.a=t2.a)
when matched then update set b= nvl(t2.m,seq_teste.nextval);
One thing: that nextval will ALWAYS be consumed even when it won't be inserted. If you don't want that, you might need some pl/sql code.
I have two tables, two differently name columns in these tables match up.
Table A:
a
b
c
d
e
Table B:
f
g
h
I need to display a grid view of e, g and h, Joining the tables together based on the f and b matching up. I know how to fill a grid view based on a query, its just the query itself I'm after.
Since all of your columns are uniquely named, and you are joining two different tables, no aliasing is necessary, and you don't need to fully qualify the column names.
The SQL term you are looking for is a JOIN. In this case, it sounds like you want an inner join (there are many ways to write them).
SELECT
e,g,h
FROM
TableA
INNER JOIN TableB
ON b = f
You used the very words in your question: "joining the tables together based on the f and b matching up".
SELECT e,g,h FROM `Table A` JOIN `Table B` ON f=b
I think it might be:
SELECT e,g,h FROM Table A, Table B WHERE Table A.b == Table B.f
That's the JOIN I would use. It may need tweaked depending on what your variables are.
Sorry, this works for SQL not MYSQL.