I need to render a query such that every column contains the count of a respective table.
The code I have now is:
SELECT COUNT(table1.Id),
COUNT(table2.Id),
COUNT(table3.Id)
FROM table1,
table2,
table3
WHERE table1.done = 'No' OR
table2.done = 'No' OR
table3.done = 'No' OR
But I need the query to return the same result values as if every table would be counted independently, like:
SELECT COUNT(tableX.Id) FROM tableX WHERE talbeX.done = 'No'
where the 'X' stands for 1,2 or 3.
How can this be achived with SQL?
Thanks beforhand for the help.
Just use a nested sub query, exactly as you have explained it:
SELECT
(SELECT COUNT(table1.Id) FROM table1 WHERE table1.done = 'No') as T1Count,
(SELECT COUNT(table2.Id) FROM table2 WHERE table2.done = 'No') as T2Count,
(SELECT COUNT(table3.Id) FROM table3 WHERE table3.done = 'No') as T3Count,
(SELECT COUNT(tableN.Id) FROM tableN) as TNCount;
This will query the tables independently so you are free to use what ever additional criteria you may need without trying to correlate the results from each query
FROM in this case is not strictly necessary in the outer query as we are not returning rows from any specific table, there is no table that we could specify in the from clause. Each RDBMS has their own convention for these types of queries, MS SQL Server and Oracle are to predominant database engines used in Outsystems
If we did specify a table in FROM then this would return 1 row for every record in that table, which is inefficient and not required. So it is important that we do not include a FROM clause.
Transact-SQL - FROM
The FROM clause is usually required on the SELECT statement. The exception is when no table columns are listed, and the only items listed are literals or variables or arithmetic expressions.
ORACLE - DUAL Table
DUAL is a table automatically created by Oracle Database along with the data dictionary. DUAL is in the schema of the user SYS but is accessible by the name DUAL to all users. It has one column, DUMMY, defined to be VARCHAR2(1), and contains one row with a value X. Selecting from the DUAL table is useful for computing a constant expression with the SELECT statement. Because DUAL has only one row, the constant is returned only once. Alternatively, you can select a constant, pseudocolumn, or expression from any table, but the value will be returned as many times as there are rows in the table.
Update - OP is using Oracle!
After attempting the solution, OP responded that it raised the following error:
Error in advanced query SQL2: ORA-00923: FROM keyword not found where expected
The ORA prefix of this error number indicates that the data store is actually an Oracle implementation, so we need to append the FROM DUAL to the query.
SELECT
(SELECT COUNT(table1.Id) FROM table1 WHERE table1.done = 'No') as T1Count,
(SELECT COUNT(table2.Id) FROM table2 WHERE table2.done = 'No') as T2Count,
(SELECT COUNT(table3.Id) FROM table3 WHERE table3.done = 'No') as T3Count,
(SELECT COUNT(tableN.Id) FROM tableN) as TNCount
FROM DUAL;
To join the tables, I am using the following query.
SELECT *
FROM(select user as uservalue1 FROM [projectname.FullData_Edited]) as FullData_Edited
JOIN (select user as uservalue2 FROM [projectname.InstallDate]) as InstallDate
ON FullData_Edited.uservalue1=InstallDate.uservalue2;
The query works but the joined table only has two columns uservalue1 and uservalue2.
I want to keep all the columns present in both the table. Any idea how to achieve that?
#legacySQL
SELECT <list of fields to output>
FROM [projectname:datasetname.FullData_Edited] AS FullData_Edited
JOIN [projectname:datasetname.InstallDate] AS InstallDate
ON FullData_Edited.user = InstallDate.user
or (and preferable)
#standardSQL
SELECT <list of fields to output>
FROM `projectname.datasetname.FullData_Edited` AS FullData_Edited
JOIN `projectname.datasetname.InstallDate` AS InstallDate
ON FullData_Edited.user = InstallDate.user
Note, using SELECT * in such cases lead to Ambiguous column name error, so it is better to put explicit list of columns/fields you need to have in your output
The way around it is in using USING() syntax as in example below.
Assuming that user is the ONLY ambiguous field - it does the trick
#standardSQL
SELECT *
FROM `projectname.datasetname.FullData_Edited` AS FullData_Edited
JOIN `projectname.datasetname.InstallDate` AS InstallDate
USING (user)
For example:
#standardSQL
WITH `projectname.datasetname.FullData_Edited` AS (
SELECT 1 user, 'a' field1
),
`projectname.datasetname.InstallDate` AS (
SELECT 1 user, 'b' field2
)
SELECT *
FROM `projectname.datasetname.FullData_Edited` AS FullData_Edited
JOIN `projectname.datasetname.InstallDate` AS InstallDate
USING (user)
returns
user field1 field2
1 a b
whereas using ON FullData_Edited.user = InstallDate.user gives below error
Error: Duplicate column names in the result are not supported. Found duplicate(s): user
Don't use subqueries if you want all columns:
SELECT *
FROM [projectname.FullData_Edited] as FullData_Edited JOIN
[projectname.InstallDate] as InstallDate
ON FullData_Edited.uservalue1 = InstallDate.uservalue2;
You may have to list out the particular columns you want to avoid duplicate column names.
While you are at it, you should also switch to standard SQL.
I am trying to do MINUS on 2 tables which have same schema in big-query.As I understand MINUS is not working in biquery
You can do something like:
SELECT
field
FROM `project_id.dataset.tableA` A
WHERE NOT EXISTS(SELECT 1 FROM `project_id.dataset.tableB` b WHERE a.field = b.field)
I see that there is EXCEPT set operator in Big Query for Standard SQL.
The EXCEPT operator returns rows from the left input query that are not present in the right input query. This is similar to what the MINUS does in ORACLE/MySQL
SELECT fieldId from dataset.table1 except DISTINCT SELECT fieldId from dataset.table2
Note: the datatype of both the columns should be same in both the tables
I have a component that retrieves data from database based on the keys provided.
However I want my java application to get all the data for all keys in a single database hit to fasten up things.
I can use 'in' clause when I have only one key.
While working on more than one key I can use below query in oracle
SELECT * FROM <table_name>
where (value_type,CODE1) IN (('I','COMM'),('I','CORE'));
which is similar to writing
SELECT * FROM <table_name>
where value_type = 1 and CODE1 = 'COMM'
and
SELECT * FROM <table_name>
where value_type = 1 and CODE1 = 'CORE'
together
However, this concept of using 'in' clause as above is giving below error in 'SQL server'
ERROR:An expression of non-boolean type specified in a context where a condition is expected, near ','.
Please let know if their is any way to achieve the same in SQL server.
This syntax doesn't exist in SQL Server. Use a combination of And and Or.
SELECT *
FROM <table_name>
WHERE
(value_type = 1 and CODE1 = 'COMM')
OR (value_type = 1 and CODE1 = 'CORE')
(In this case, you could make it shorter, because value_type is compared to the same value in both combinations. I just wanted to show the pattern that works like IN in oracle with multiple fields.)
When using IN with a subquery, you need to rephrase it like this:
Oracle:
SELECT *
FROM foo
WHERE
(value_type, CODE1) IN (
SELECT type, code
FROM bar
WHERE <some conditions>)
SQL Server:
SELECT *
FROM foo
WHERE
EXISTS (
SELECT *
FROM bar
WHERE <some conditions>
AND foo.type_code = bar.type
AND foo.CODE1 = bar.code)
There are other ways to do it, depending on the case, like inner joins and the like.
If you have under 1000 tuples you want to check against and you're using SQL Server 2008+, you can use a table values constructor, and perform a join against it. You can only specify up to 1000 rows in a table values constructor, hence the 1000 tuple limitation. Here's how it would look in your situation:
SELECT <table_name>.* FROM <table_name>
JOIN ( VALUES
('I', 'COMM'),
('I', 'CORE')
) AS MyTable(a, b) ON a = value_type AND b = CODE1;
This is only a good idea if your list of values is going to be unique, otherwise you'll get duplicate values. I'm not sure how the performance of this compares to using many ANDs and ORs, but the SQL query is at least much cleaner to look at, in my opinion.
You can also write this to use EXIST instead of JOIN. That may have different performance characteristics and it will avoid the problem of producing duplicate results if your values aren't unique. It may be worth trying both EXIST and JOIN on your use case to see what's a better fit. Here's how EXIST would look,
SELECT * FROM <table_name>
WHERE EXISTS (
SELECT 1
FROM (
VALUES
('I', 'COMM'),
('I', 'CORE')
) AS MyTable(a, b)
WHERE a = value_type AND b = CODE1
);
In conclusion, I think the best choice is to create a temporary table and query against that. But sometimes that's not possible, e.g. your user lacks the permission to create temporary tables, and then using a table values constructor may be your best choice. Use EXIST or JOIN, depending on which gives you better performance on your database.
Normally you can not do it, but can use the following technique.
SELECT * FROM <table_name>
where (value_type+'/'+CODE1) IN (('I'+'/'+'COMM'),('I'+'/'+'CORE'));
A better solution is to avoid hardcoding your values and put then in a temporary or persistent table:
CREATE TABLE #t (ValueType VARCHAR(16), Code VARCHAR(16))
INSERT INTO #t VALUES ('I','COMM'),('I','CORE')
SELECT DT. *
FROM <table_name> DT
JOIN #t T ON T.ValueType = DT.ValueType AND T.Code = DT.Code
Thus, you avoid storing data in your code (persistent table version) and allow to easily modify the filters (without changing the code).
I think you can try this, combine and and or at the same time.
SELECT
*
FROM
<table_name>
WHERE
value_type = 1
AND (CODE1 = 'COMM' OR CODE1 = 'CORE')
What you can do is 'join' the columns as a string, and pass your values also combined as strings.
where (cast(column1 as text) ||','|| cast(column2 as text)) in (?1)
The other way is to do multiple ands and ors.
I had a similar problem in MS SQL, but a little different. Maybe it will help somebody in futere, in my case i found this solution (not full code, just example):
SELECT Table1.Campaign
,Table1.Coupon
FROM [CRM].[dbo].[Coupons] AS Table1
INNER JOIN [CRM].[dbo].[Coupons] AS Table2 ON Table1.Campaign = Table2.Campaign AND Table1.Coupon = Table2.Coupon
WHERE Table1.Coupon IN ('0000000001', '0000000002') AND Table2.Campaign IN ('XXX000000001', 'XYX000000001')
Of cource on Coupon and Campaign in table i have index for fast search.
Compute it in MS Sql
SELECT * FROM <table_name>
where value_type + '|' + CODE1 IN ('I|COMM', 'I|CORE');
Debugging an app which queries SQL Server 05, can't change the query but need to optimise things.
Running all the selects seperately are quick <1sec, eg: select * from acscard, select id from employee... When joined together it takes 50 seconds.
Is it better to set uninteresting accesscardid fields to null or to '' when using EXISTS?
SELECT * FROM ACSCard
WHERE NOT EXISTS
( SELECT Id FROM Employee
WHERE Employee.AccessCardId = ACSCard.acs_card_number )
AND NOT EXISTS
( SELECT Id FROM Visit
WHERE Visit.AccessCardId = ACSCard.acs_card_number )
ORDER by acs_card_id
Do you have indexes on Employee.AccessCardId, Visit.AccessCardId, and ACSCard.acs_card_number?
The SELECT clause is not evaluated in an EXISTS clause. This:
WHERE EXISTS(SELECT 1/0
FROM EMPLOYEE)
...should raise an error for dividing by zero, but it won't. But you need to put something in the SELECT clause for it to be a valid query - it doesn't matter if it's NULL or a zero length string.
In SQL Server, NOT EXISTS (and NOT IN) are better than the LEFT JOIN/IS NULL approach if the columns being compared are not nullable (the values on either side can not be NULL). The columns compared should be indexed, if they aren't already.