I am attempting to query a table in BigQuery programmatically, and have a WHERE-IN clause that I would like to support having NULL as the value. Current Query looks like:
SELECT * FROM DATASET.TABLE_NAME WHERE HIT_DATE = 'YYYY-MM-DD' AND ID IN (LIST_OF_IDS);
I am wondering if there is a way so that I can query everything from the table for a specific date in the case that the LIST_OF_IDS input is NULL (The idea being that I want to support choosing between an inputting of a list of ids or return everything if no list of ids are given).
I tried
SELECT * FROM DATASET.TABLE_NAME WHERE HIT_DATE = 'YYYY-MM-DD' AND ID IN (LIST_OF_IDS) IS NOT NULL;
But got this error thrown at me:
Syntax error: Expression to the left of IS must be parenthesized
If I understand correctly you are looking for this :
SELECT *
FROM DATASET.TABLE_NAME
WHERE HIT_DATE = 'YYYY-MM-DD'
AND (ID IN (LIST_OF_IDS) OR LIST_OF_IDS IS NULL);
Related
I'm just taking a look at the following query
select * from tablename
where id like '%%';
So that it can handle parameters to include all of the data or filtered data like bellow
select * from tablename
where id like '%1%';
Which is fine for most parameters I use but this seems wrong for an ID because it will return all data that has IDs containing 1 which I don't want
To get around this I can only append the where clause if the ID is given but that seems like a pain in the butt
Is it possible to use a different type of where clause so that a wildcard can be used in a where equals clause instead of a where like clause, example
select * from tablename
where id = '*';
So that the same query can be used to return all or filtered data? Pass parameter '*' for all or parameter '1' for ID 1 specifically
(I'm not sure if it matters for this case but I'm using PostgreSQL 9.6.12 in this example)
This would often be expressed as:
where (id = :id or :id is null)
null is the "magic" value that represents all rows.
A query can return an empty table on BigQuery. An example of such occurrence is if I join a bunch of tables in a query on BigQuery and the result of the joins is an empty table, or if there are no matches based on the where clause.
Here is a dumb sample query that will always return in an empty join:
#standardSQL
WITH query1 AS (
SELECT 1 AS number, "one" AS message
), query2 AS (
SELECT 2 AS number, "two" AS message)
SELECT "query result" AS result, query1.*
FROM query1
JOIN query2 ON query1.number = query2.number;
The query will show this output: Query returned zero records.
If that's the case I want to return either a message or a default row. But I don't know how to do that. I've tried using IFNULL, but that's only usuable for one column, not number of columns. Using an IF statement gave me errors as you can't return row(s) from an if statement.
I think the error it gave me was Scalar subquery cannot have more than one column unless using SELECT AS STRUCT to build STRUCT values.
Another thing that I could think of, but don't know how to implement is to add a UNION at the end that would only trigger if the previous parts didn't return anything. Or wrap the existing query in a WITH statement subquery and if that returns nothing, print a message, else do SELECT * FROM sub_query.
I'd like to either just display a message when an empty table is the result, or return a row with some default values.
I understand the answer is likely to contain a UNION statement and hence displaying just a message won't be possible. In that case I'd like to display a default row instead. For the above sample query a default row would look like: "No results found", NULL, NULL.
When the query returns a non empty table, I want it to look exactly like it did with the original query. So there shouldn't be any added columns or change to the schema of the result.
You would use union all. Something like this:
with t as (
. . . <all your query stuff here>
)
select cast(NULL as string) as msg, t.*
from t
union all
select msg, t.* -- all the `t` columns will be `NULL`
from (select 'No rows returned' as msg) left join
t
on 1 = 0 -- always false
where not exists (select 1 from t);
Note the complications. A query returns a fixed set of columns with a fixed set of names. This version returns an extra column at the beginning of the data to contain the message. In order to get all the rest of the columns, a left join is used, but the on clause is always false.
Option 1
Below displays row with all nulls in case if there is no result returned for your_query
#standardSQL
WITH your_query AS ( ... )
SELECT * FROM your_query
UNION ALL
SELECT your_query.* REPLACE ("No results found" AS result)
FROM (SELECT 1)
LEFT JOIN your_query ON FALSE
WHERE NOT EXISTS (SELECT 1 FROM your_query)
Row result number message
1 No results found null null
Option 2
If you know in advance output schema - below returns default row (assuming 0 default for number and "none" default for message
#standardSQL
WITH your_query AS ( ... )
SELECT * FROM your_query
UNION ALL
SELECT "No results found", 0, "none" FROM (SELECT 1)
LEFT JOIN your_query ON FALSE
WHERE NOT EXISTS (SELECT 1 FROM your_query)
Row result number message
1 No results found 0 none
Let's say that we have a table named Data with Id and Weather columns. Other columns in that table are not important to this problem. The Weather column can be null.
I want to display all rows where Weather fits a condition, but if there is a null value in weather then display null value.
My SQL so far:
SELECT *
FROM Data d
WHERE (d.Weather LIKE '%'+COALESCE(NULLIF('',''),'sunny')+'%' OR d.Weather IS NULL)
My results are wrong, because that statement also shows values where Weather is null if condition is not correct (let's say that users mistyped wrong).
I found similar topic, but there I do not find appropriate answer.
SQL WHERE clause not returning rows when field has NULL value
Please help me out.
Your query is correct for the general task of treating NULLs as a match. If you wish to suppress NULLs when there are no other results, you can add an AND EXISTS ... condition to your query, like this:
SELECT *
FROM Data d
WHERE d.Weather LIKE '%'+COALESCE(NULLIF('',''),'sunny')+'%'
OR (d.Weather IS NULL AND EXISTS (SELECT * FROM Data dd WHERE dd.Weather LIKE '%'+COALESCE(NULLIF('',''),'sunny')+'%'))
The additional condition ensures that NULLs are treated as matches only if other matching records exist.
You can also use a common table expression to avoid duplicating the query, like this:
WITH cte (id, weather) AS
(
SELECT *
FROM Data d
WHERE d.Weather LIKE '%'+COALESCE(NULLIF('',''),'sunny')+'%'
)
SELECT * FROM cte
UNION ALL
SELECT * FROM Data WHERE weather is NULL AND EXISTS (SELECT * FROM cte)
statement show also values where Wether is null if condition is not correct (let say that users typed wrong sunny).
This suggests that the constant 'sunny' is coming from end-user's input. If that is the case, you need to parameterize your query to avoid SQL injection attacks.
This may be simple, but I am no SQL whiz so I am getting lost. I understand that sql takes your query and executes it in a certain order, which I believe is why this query does not work:
select * from purchaseorders
where IsNumeric(purchase_order_number) = 1
and cast(purchase_order_number as int) >= 7
MOST of the purchar_order_number fields are numeric, but we introduce alphanumeric ones recently. The data I am trying to get is to see if '7' is greater than the highest numeric purchase_order_number.
The Numeric() function filters out the alphanumeric fields fine, but doing the subsequent cast comparison throws this error:
Conversion failed when converting the nvarchar value '124-4356AB' to data type int.
I am not asking what the error means, that is obvious. I am asking if there is a way to accomplish what I want in a single query, preferably in the where clause due to ORM constraints.
does this work for you?
select * from purchaseorders
where (case when IsNumeric(purchase_order_number) = 1
then cast(purchase_order_number as int)
else 0 end) >= 7
You can do a select with a subselect
select * from (
select * from purchaseorders
where IsNumeric(purchase_order_number) = 1) as correct_orders
where cast(purchase_order_number as int) >= 7
try this:
select * from purchaseorders
where try_cast(purchase_order_number as int) >= 7
have to check which column has numeric values only.
Currently, in a table every field is setted with nvarchar(max) Like tableName (field1 nvarchar(max),field2 nvarchar(max),field3 nvarchar(3)) and tableName has 25lac Rows.
But on manually Check Field2 Contain the numeric Values Only... How to Check With t-sql that in the Complete Column (Field2) has numeric Value or not/null value with Longest Length in the Column!
I'm trying to create an Oracle query that will use a parameter based on the CommandName of a button.
So here's my query
SELECT id
FROM table
WHERE dateTime IS (CASE WHEN :CommandName = 'FIRST' THEN NULL ELSE NOT NULL END)
So I'm passing the parameter but it's not working - I'm just getting a Missing NULL keyword error
I basically don't want to have to write two separate queries based on the parameter that is input
Not even sure if this is possible or if this is the right way of doing it?
Any ideas?
You may want to read up on the CASE statement a bit more.
I believe you want the following code:
SELECT
id
FROM
table
WHERE
(
(dateTime IS NULL AND :CommandName = 'FIRST')
OR
(dateTime IS NOT NULL AND NVL(:CommandName, '') <> 'FIRST')
)
Without using dynamic SQL to return the string 'NULL' or 'NOT NULL' you could use two NVL() functions:
select id
from table
where NVL(dateTime,'FIRST') = NVL(:param,dateTime);
However, if dateTime is indexed (and Oracle can index NULLs), ths NVL() function will disable the index.
I think that
SELECT id
FROM table
WHERE (dateTime IS NULL AND :CommandName='FIRST') OR (dateTime IS NOT NULL AND :CommandName <> 'FIRST')
should do what you need.