can we have the display command with certain conditions ,
For example, if we want to just print things their value are bigger than 7 . in other word how can we have
Display $( x.val> 7)
In general, is it possible to have condition on display command?
Yes, you can use the $ condition on a Display statement like in any, e.g., assignment statement:
Scalar x /2/;
Display$(x>3) 'X is greater than 3';
Display$(x>1) 'X is greater than 1';
Related
I am trying to sequentially grab the first record that matches the greater than or equal query on the xmin column compared to an incrementing integer in PostgreSQL. My query looks like this at execution time:
SELECT xmin, column1, column2, column3 FROM records WHERE xmin >= $1 LIMIT 1 ;
And then at call time, I pass the args 1 to the query through the standard sql.QueryRow function.
However, I expect to be getting back a row, instead I'm returned the following error.
pq: operator does not exist: xid >= unknown
Two things here: I can't figure out where xid is coming from since I never query for it, and I can't figure out why the placeholder value is not being added correctly either. The argument is getting passed to the query at call time, it's not nil or anything, but the Postgres engine doesn't like my query.
If you had 'blah' >= 4 the error would say something like operator does not exist: text >= integer. The xid is a type not a column. It isn't an integer and can't directly be compared to one.
You can do xid::text::bigint >= $1 if you really want to but make sure you understand the implications of transaction wrap-around.
Let me repeat that last point - go away and read up about how PostgreSQL transaction IDs work before you start trying to compare them numerically.
I have a text column that has a data value (int) within it that I need to parse out. The problem is that it is not in the same character column, so a simple substring(x, 180, 5) won't work as it sometimes will return a character as well.
The data value always comes after the phrase 'value received:'.
Is it possible to parse the value out whereby SQL will take the next 3 values after this wording? Or even better, can you "catch" the value between two words? As before the value is a : and after the value there is always the word "complete".
You can use something like this:
select substring(x, charindex('value received', x) + 14, 5)
Without sample data, this might be off by a character or two.
I have a table 'article' with column 'content' .I want to query Postgresql in order to search for a string contained in variable 'temp'.This query works fine-
pool.query("select * from article where upper(content) like upper('%some_value%')");
But when I use placeholder $1 and [temp] in place of some_value , I get the above error -
pool.query("select * from article where upper(content) LIKE upper('%$1%')",[temp] );
Note - Here $1 is a placeholder and should be replaced by the value in [temp] , but it treats '%$1%' as a string , I guess. Without the quotes ' ' , the LIKE operator doesn't work. I have also tried the query -
pool.query("select * from article where upper(content) LIKE upper(concat('%',$1,'%'))",[temp] );
to ensure $1 is not treated as a string literal but it gives the error -
error: could not determine data type of parameter $1
pool.query(
"select * from article where upper(content) LIKE upper('%' || $1 || '%')",
[temp]
).then( res => {console.log(res)}, err => {console.error(err)})
This works for me. I just looked at this Postgres doc page to try and understand what concat was doing to the parameter notation. Can't say that I understand the difference between using || operators and using concat string function at this time.
The easiest way I found to do this is like the following:
// You can remove [0] from character[0] if you want the complete value of character.
database.query(`
SELECT * FROM users
WHERE LOWER(users.name) LIKE LOWER($1)
ORDER BY users.id ASC`,
["%" + character[0] + "%"]
);
// [%${character}%] string literal alternative to the last line in the function call.
There are several things going on here, so let me break each line it down.
SELECT * FROM users
This is selecting all the columns associated with table users
WHERE LOWER(users.name) LIKE $1
This is filtering out all the results from the first line so that where the name(lowercased) column of the users table is like the parameter $1.
ORDER BY users.id ASC
This is optional, but I like to include it because I want the data returned to me to be in ascending order (that is from 0 to infinity, or starting low and going high) based on the users.id or the id column of the users table. A popular alternative for client-side data presentation is users.created_at DESC which shows the latest user (or more than likely an article/post/comment) by its creation date in reverse order so you get the newest content at the top of the array to loop through and display on the client-side.
["%" + character + "%"]
This part is the second argument in the .query method call from the database object (or client if you kept with that name, you can name it what you want, and database to me makes for more a sensical read than "client", but that is just my personal opinion, and it's highly possible that "client" may be the more technically correct term to use).
The second argument needs to be an array of values. It takes the place of the parameters inserted in the query string, for example, $1 or ? are examples of parameter placeholders which are filled in with a value in the 2nd argument's array of values. In this case, I used JavaScript's built-in string concatenation to provide a "includes" like pattern, or in plain-broken English, "find me columns that contain a 'this' value" where name(lowercased) is the column and character is the parameter variable value. I am pulling in the parameter value for the character variable from req.params (the URL, so http://localhost:3000/users/startsWith/t), so combining that with % on both ends of the parameter, it returns me all the values that contain the letter t since is the first (and only) character here in the URL.
I know this is a VERY late response, but I wanted to respond with a more thorough answer in case anyone else needed it broken down further.
In my case :
My variable was $1, instead of ?1 ...
I was customizing my query with #Query
In my report query I have a where clause that needs to be replaced dynamically based on the data chosen in the front end.
The query is something like :
where ?=?
I already have a code to replace the value - I created report parameter and linked to the value ? in the query.
Example:
where name=?
Any value of name that comes from front end replaces the ? in the where clause - this works fine.
But now I need to replace the entire clause (where ?=?). Should I create two parameters and link them to both the '?' ?
No, unfortunately most database engines do not allow to use a query parameter for handling a dynamic column name. This is for security considerations.
So you need to keep an arbitrary column name in the query:
where name=?
And then in "beforeOpen" script of the dataset replace 'name' with a report parameter value:
this.queryText=this.queryText.replace("name",params["myparameter"].value);
To prevent SQLIA i recommend to test the value of the parameter in this script. There are many ways to do this but a white list is the strongest test, for example:
var column=params["myparameter"].value;
if (column=="name" || column=="id" || column=="account" || column=="mycolumnname"){
this.queryText=this.queryText.replace("name",column);
}
In addition to Dominique's answer and your comment, then you'll just need a slightly more advanced logic.
For example, you could name your dynamic column-name-value pairs (column1, value1), (column2, value2) and so on. In the static text of the query, make sure to have bind variables for value1, value2 and so on (for example, with Oracle SQL, using the syntax
with params as (
select :value1 as value1,
:value2 as value2 ...
from dual
)
select ...
from params, my_table
where 1=1
and ... static conditions....
Then, in the beforeOpen script, append conditions to the query text in a loop as needed (the loop left as an exercise to the reader, and don't forget checking the column names for security reasons!):
this.queryText += " and " + column_name[i] + "= params.value" + i;
This way you can still use bind variables for the comparison values.
I have a report in 2005 SSRS which I want to add a parameter to. The parameter would be comprised of a group of zip codes, but be selected as a single item in the list.
For example, I would like to have 5 zip codes as one selection in the list and 3 for another, etc:
Select 11111,22222,33333,44444,55555,66666 AS Boondock
Select 77777,88888,99999 AS Timbuck
Select Zip Codes NOT IN (11111-99999) AS Everything Else
So my selections in the dropdown would be:
Boondock
Timbuck
Everything Else
Can anyone help me with how I should go about creating this parameter?
Create a simple string parameter to present to the user. Let's call it ZipCodeSet.
Create a dataset that examines the #ZipCodeSet parameter and returns the appropriate list of zip codes. Call it ZipCodeSelection.
Create an internal multivaue parameter that uses ZipCodeSelection as both its Available Values and Default Values. Call it SelectedZipCodes.
Use SelectedZipCodes in your report's datasets.
The easiest solution here would probably to use a Calculated Field on your dataset, called LocationDescription, for example:
=SWITCH(Fields!ZipCode >= 11111 and Fields!ZipCode <= 66666, "Boondock", Fields!ZipCode >= 77777 and Fields!ZipCode <= 99999, "Timbuck",True, "Everywhere Else")
The lone true statement at the end is due to the SWITCH expression reading left-to-right and exiting once it evaluates one of the switches as TRUE. This way for each of the items in your table of ZipCodes you will always end up with a TRUE result.
I assume you're evaluating a range of ZipCodes, and not exact values of 11111,22222, and so on? If so, the switch will have more values. A sample of your data would help if you want an exact answer.
Once you have built your Calculated Field, you can then set up a Parameter (called #LocationParameter) with available values based on a query of your LocationDescription field, then just filter your dataset using:
Expression:
= Fields!LocationDescription
Operator: =
Value:
#LocationParameter
(if you want multiple selections on your parameter, change the operator to IN)
Hope that helps.