How can I write a select query to view a few columns from a table and add additional columns to it with a default value assigned?
Like Select a,b,c, d="TIM" from table1;,
where a,b and c are columns in table1, but "d" isn't.
Like this
select a, b, c, 'TIM' as d
from your_table
You can just select a constant value:
Select t1.a, t1.b, t1.c, 'TIM' as d
from table1 t1;
Note that SQL in general -- and Oracle in particular -- uses single quotes to delimit strings.
I assume you want to fetch the rows from table1 where d='TIM' from another table and the ids of these tables are their common fields:
SELECT t1.a,t1.b,t1.c,t2.d
FROM table1 t1
JOIN table2 t2 ON t1.id = t2.id
WHERE t2.d = 'TIM';
Related
So, I have a table with the following structure:
id
columnA
columnB
1
Yes
1
No
I want to combine the row into a single row, so it ends up like this:
id
columnA
columnB
1
Yes
No
I believe a self join here would work like this:
SELECT t1.columnA , t2.columnB
FROM table1 t1, table1 t2
where t1.id = t2.id
But is there a way to do this without specifying the columns? I have a table that has 100 columns and I'm trying to see if I can accomplish this without listing out all the columns.
Use the below query to get the column name with aggregation (Query created using information schema to get the column names). Write a select using the result and run the query.
select
case when column_name='Id' then column_name
else concat(',Max(', column_name,')') end as Name
from information_schema.columns
where table_name = 'Table1';
You will get something like below as output, where A and B are the column names.
Id
,Max(A)
,Max(B)
Add convert the result to query
Select
Id
,Max(A)
,Max(B)
from Table1 Group by Id
is there a way to do this without specifying the columns?
You can use using to answer your question.
SELECT t1.columnA , t2.columnB
FROM table1 t1 JOIN
table1 t2
USING (id);
To get the data you want, use aggregation:
SELECT id, MAX(t1.columnA), MAX(t2.columnB)
FROM table1 t1
GROUP BY id;
Use your JOIN only change the colums for *
SELECT t1.*, t2.*
FROM table1 t1, table1 t2
where t1.id = t2.id
Table1: Columns A, B, C
Table2: Columns A, B, C
Table 2 is a copy of Table 1 with different data. Assume all columns to be varchar
Looking for a single efficient query which can fetch:
Columns A, B, C from Table1
Additional Rows from Table2 where values of Table2.A are not present in Table1.A
Any differences between the Oracle SQL & HQL for the same query will be appreciated.
I'm fiddling with Joins, Unions & Minus but not able to get the correct combination.
SQL:
SELECT *
FROM Table1
UNION ALL
SELECT *
FROM Table2 T2
WHERE NOT EXISTS(
SELECT 'X' FROM Table1 T1
WHERE T1.A = T2.A
)
HQL:
You must execute two different query an discard the element by Table2 result in a Java loop because in HQL doesn't exist UNION command.
Alternatatively you can write the first query for Table1 and the second query must have a not in clause to discard Table1 A field.
Solution 1:
Query 1:
SELECT * FROM Table1
Query 2:
SELECT * FROM Table2
and then you apply a discard loop in Java code
Solution 2:
Query 1:
SELECT * FROM Table1
Query 2:
SELECT * FROM Table2 WHERE Table2.A not in (SELECT Table1.A from Table1)
This query returns all rows in table1, plus all rows in table2 which does not exist in table1, given that column a is the common key.
select a,b,c
from table1
union
all
select a,b,c
from table2
where a not in(select a from table1);
There may be different options available depending on the relative sizes of table1 and table2 and the expected overlap.
I want to select all records from a table T1 where the values in columns A and B has no matching tuple for the columns C and D in table T2.
In mysql “Where not in” using two columns I can read how to accomplish that using the form select A,B from T1 where (A,B) not in (SELECT C,D from T2), but that fails in T-SQL for me resulting in "Incorrect syntax near ','.".
So how do I do this?
Use a correlated sub-query:
...
WHERE
NOT EXISTS (
SELECT * FROM SecondaryTable WHERE c = FirstTable.a AND d = FirstTable.b
)
Make sure there's a composite index on SecondaryTable over (c, d), unless that table does not contain many rows.
You can't do this using a WHERE IN type statement.
Instead you could LEFT JOIN to the target table (T2) and select where T2.ID is NULL.
For example
SELECT
T1.*
FROM
T1 LEFT OUTER JOIN T2
ON T1.A = T2.C AND T1.B = T2.D
WHERE
T2.PrimaryKey IS NULL
will only return rows from T1 that don't have a corresponding row in T2.
I Used it in Mysql because in Mysql there isn't "EXCLUDE" statement.
This code:
Concates fields C and D of table T2 into one new field to make it easier to compare the columns.
Concates the fields A and B of table T1 into one new field to make it easier to compare the columns.
Selects all records where the value of the new field of T1 is not equal to the value of the new field of T2.
SQL-Statement:
SELECT T1.* FROM T1
WHERE CONCAT(T1.A,'Seperator', T1.B) NOT IN
(SELECT CONCAT(T2.C,'Seperator', T2.D) FROM T2)
Here is an example of the answer that worked for me:
SELECT Count(1)
FROM LCSource as s
JOIN FileTransaction as t
ON s.TrackingNumber = t.TrackingNumber
WHERE NOT EXISTS (
SELECT * FROM LCSourceFileTransaction
WHERE [LCSourceID] = s.[LCSourceID] AND [FileTransactionID] = t.[FileTransactionID]
)
You see both columns exist in LCSourceFileTransaction, but one occurs in LCSource and one occurs in FileTransaction and LCSourceFileTransaction is a mapping table. I want to find all records where the combination of the two columns is not in the mapping table. This works great. Hope this helps someone.
If I run the two statements in batch will they return one table to two to my sqlcommand object with the data merged. What I am trying to do is optimize a search by searching twice, the first time on one set of data and then a second on another. They have the same fields and I’d like to have all the records from both tables show and be added to each other. I need this so that I can sort the data between both sets of data but short of writing a stored procedure I can’t think of a way of doing this.
Eg. Table 1 has columns A and B, Table 2 has these same columns but different data source. I then wan to merge them so that if a only exists in one column it is added to the result set and if both exist it eh tables the column B will be summed between the two.
Please note that this is not the same as a full outer join operation as that does not merge the data.
[EDIT]
Here's what the code looks like:
Select * From
(Select ID,COUNT(*) AS Count From [Table1]) as T1
full outer join
(Select ID,COUNT(*) AS Count From [Table2]) as T2
on t1.ID = T2.ID
Perhaps you're looking for UNION?
IE:
SELECT A, B FROM Table1
UNION
SELECT A, B FROM Table2
Possibly:
select table1.a, table1.b
from table1
where table1.a not in (select a from table2)
union all
select table1.a, table1.b+table2.b as b
from table1
inner join table2 on table1.a = table2.a
edit: perhaps you would benefit from unioning the tables before counting. e.g.
select id, count() as count from
(select id from table1
union all
select id from table2)
I'm not sure if I understand completely but you seem to be asking about a UNION
SELECT A,B
FROM tableX
UNION ALL
SELECT A,B
FROM tableY
To do it, you would go:
SELECT * INTO TABLE3 FROM TABLE1
UNION
SELECT * FROM TABLE2
Provided both tables have the same columns
I think what you are looking for is this, but I am not sure I am understanding your language correctly.
select id, sum(count) as count
from (
select id, count() as count
from table1
union all
select id, count() as count
from table2
) a
group by id
I have a database with two tables (Table1 and Table2). They both have a common column [ColumnA] which is an nvarchar.
How can I select this column from both tables and return it as a single column in my result set?
So I'm looking for something like:
ColumnA in Table1:
a
b
c
ColumnA in Table2:
d
e
f
Result set should be:
a
b
c
d
e
f
SELECT ColumnA FROM Table1 UNION Select ColumnB FROM Table2 ORDER BY 1
Also, if you know the contents of Table1 and Table2 will NEVER overlap, you can use UNION ALL in place of UNION instead. Saves a little bit of resources that way.
-- Kevin Fairchild
Do you care if you get dups or not?
UNION will be slower than UNION ALL because UNION will filter out dups
Use the UNION operator:
SELECT ColumnA FROM Table1
UNION
SELECT ColumnA FROM Table2
The union answer is almost correct, depending on overlapping values:
SELECT distinct ColumnA FROM Table1
UNION
SELECT distinct ColumnA FROM Table2
If 'd' appeared in Table1 or 'c' appeared in Table2 you would have multiple rows with them.
You can use a union select:
Select columnA from table1 union select columnA from table2
SELECT Table1.*, Table2.d, Table2.e, Table2.f
FROM Table1 JOIN Table2 ON Table1.a = Table2.a
Or am I misunderstanding your question?
Edit: It appears I did.
I believe it's:
SELECT columna FROM table1 UNION SELECT columnb FROM table2;
In Oracle (at least) there is UNION and UNION ALL, UNION ALL will return all results from both sets even if there are duplicates, where as UNION will return the distinct results from both sets.